PleasureCraft Engine Group 5.0L, 6.0L, 8.1L, 5.7L, MEFI 4 5.0L Diagnostic Manual

...

MEFI 4 / 4B

DIAGNOSTIC

MANUAL

5.0/5.7/6.0/8.1L

L510005P

11/05

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Marine Electronic Fuel Injection (MEFI 4 / 4B)

Contents

Section 1 - General Information ........................................................................................................................Page 1-1

Section 2 - ECM and Sensors ..........................................................................................................................Page 2-1

Section 3A - Fuel Metering System (5.0/5.7L) ................................................................................................ Page 3A-1

Section 3B - Fuel Metering System (6.0L) .....................................................................................................Page 3B-1

Section 3C - Fuel Metering System (8.1L) .................................................................................................... Page 3C-1

Section 4A - Ignition System (5.0/5.7L) ..........................................................................................................Page 4A-1

Section 4B - Ignition System (6.0/8.1L) ..........................................................................................................Page 4B-1

Section 5 - Diagnosis ........................................................................................................................................Page 5-1

Section 6 - PCV System ...................................................................................................................................Page 6-1

Section 7 - Symptoms .......................................................................................................................................Page 7-1

Section 8 - Master Speciﬁ cations ......................................................................................................................Page 8-1

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5.0/5.7/6.0L/8.1L General Information 1 - 1

Marine Electronic Fuel Injection (MEFI) Section 1 General Information

Contents

General Description .............................................Page 2

Visual/Physical Inspection ...............................Page 2

Basic Knowledge and Tools Required .............Page 2

Electrostatic Discharge Damage ..................... Page 2

Engine Wiring................................................... Page 2

Engine Control Module (ECM)

Self-Diagnostics............................................... Page 2

Malfunction Indicator Lamp (MIL) ................... Page 2

Intermittent Malfunction Indicator Lamp

(MIL) ......................................................... Page 3

Reading Diagnostic Trouble Codes

(DTCs) ......................................................Page 3

Service Mode ............................................Page 3

Normal Mode.............................................Page 3

MEFI On-Board Diagnostic (OBD)

System Check.................................................. Page 3

DLC Scan Tools ............................................... Page 3

Scan Tool Use With Intermittents..................... Page 4

How Diagnostic Trouble Codes Are Set........... Page 4

Clearing Diagnostic Trouble Codes

(Non-Scan) ...................................................... Page 4

Clearing Diagnostic Trouble Codes (Scan) ......Page 5

Non-Scan Diagnosis of Driveability Concerns

(No DTCs Set) .................................................Page 5

Aftermarket (Add-On) Electrical and

Vacuum Equipment...........................................Page 5

Use of Circuit Testing Tools...............................Page 5

Tools Needed to Service the System ...............Page 5

Service Precautions..........................................Page 6

Test Light Amperage Draw Test........................Page 6

Special Tools (1 of 3) .......................................Page 7

Special Tools (2 of 3) .......................................Page 8

Special Tools (3 of 3) .......................................Page 9

Abbreviations.......................................................Page 10

Diagnosis .............................................................Page 11

On-Board Service ................................................Page 11

Wiring Harness Service..................................Page 11

Wiring Connector Service...............................Page 12

Metri-Pack Series 150 Terminals..............Page 12

Weather-Pack Connectors........................Page 13

Micro-Pack 100/W Series Connectors .....Page 14

MEFI 4 - PCM

1 - 2 General Information 5.0/5.7/6.0/8.1L

near a highly charged object and momentarily touches

General Description

Visual and Physical Inspection

Important: This visual and physical inspection is

very important. Perform this inspection carefully and thoroughly. Perform a careful visual and physical inspection when performing any diagnostic procedure. This can often lead to repairing a problem without further steps. Use the following guidelines when performing a visual and physical inspection:

• Inspect all vacuum hoses for the following

conditions:

– Correct routing – Pinches

ground. Charges of the same polarity are drained off, leaving the person highly charged with the opposite polarity. Static charges of either type can cause damage. Therefore, it is important to use care when handling and testing electronic components.

Engine Wiring

When it is necessary to move any of the wiring, whether to lift wires away from their harnesses or move harnesses to reach some component, take care that all wiring is replaced in its original position and all harnesses are routed correctly. If clips or retainers break, replace them. Electrical problems can result from wiring or harnesses becoming loose and moving from their original positions, or from being rerouted.

– Cuts – Disconnects

• Inspect all wires in the engine compartment for the

following conditions:

– Proper connections – Burned or chafed spots – Pinched wires – Contact with sharp edges – Contact with hot exhaust manifolds

Basic Knowledge and Tools Required

To use this manual most effectively, a general understanding of basic electrical circuits and circuit testing tools is required. You should be familiar with wiring diagrams, the meaning of voltage, ohms, amps and the basic theories of electricity. You should also understand what happens if a circuit becomes open, shorted to ground or shorted to voltage.

To perform system diagnostics, several special tools and equipment are required. Please become acquainted with the tools and their use before attempting to diagnose the system. Special tools that are required for system service are illustrated in this section.

Electrostatic Discharge Damage

Electronic components used in control systems are often designed to carry very low voltage, and are very susceptible to damage caused by electrostatic discharge. It is possible for less than 100 volts of static electricity to cause damage to some electronic components. By comparison, it takes as much as 4,000 volts for a person to feel the zap of a static discharge.

There are several ways a person can become statically charged. The most common methods of charging are by friction and by induction. An e xample of charging b y friction is a person sliding across a seat, in which a charge of as much as 25,000 volts can build up. Charging by induction occurs when a person with well insulated shoes stands

Engine Control Module (ECM) SelfDiagnostics

The Engine Control Module (ECM) performs a continuous self-diagnosis on certain control functions. This diagnostic capability is complemented by the diagnostic procedures contained in this manual. The ECM’s language for communicating the source of a malfunction is a system of Diagnostic Trouble Codes (DTC’s). The DTC’s are two digit numbers that can range from 12 to 81. When a malfunction is detected by the ECM, a DTC is set and the Malfunction Indicator Lamp (MIL) is illuminated.

Malfunction Indicator Lamp (MIL)

The Malfunction Indicator Lamp (MIL) is part of the Marine Diagnostic Trouble Code (MDTC) tool, or it can be a dash mounted warning light on some boat models.

If present, it informs the operator that a problem has

•

occurred and that the boat should be taken for service as soon as reasonably possible.

It displays DTC’s stored by the ECM which help the

•

technician diagnose system problems.

As a bulb and system check, the light will come “ON” with the key “ON,” engine “OFF.” When the engine is star ted, the light will turn “OFF.” If the light remains “ON,” the self-diagnostic system has detected a problem. If the problem goes away, the light may go out, but a DTC will remain stored in the ECM.

When the light remains “ON” while the engine is running, or when a malfunction is suspected due to a driveability problem, the MEFI “On-Board Diagnostic (OBD) System Check” must be performed as the ﬁ rst step. These checks will expose malfunctions which may not be detected if other diagnostics are performed prematurely.

MEFI 4 - PCM

5.0/5.7/6.0L/8.1L General Information 1 - 3

Intermittent Malfunction Indicator Lamp (MIL)

In the case of an “intermittent” problem, the Malfunction Indicator Lamp (MIL) will light for 10 seconds, and then go out. However, the corresponding DTC will be stored in the memory of the ECM. When DTC’s are set by an intermittent malfunction, they could be helpful in diagnosing the system.

If an intermittent DTC is cleared, it may or may not reset. If it is an intermittent failure, consult the “Diagnostic Aids” on the facing page of the corresponding Diagnostic Procedure. Symptoms section also covers the topic of “Intermittents.” A physical inspection of the applicable sub-system most often will resolve the problem.

Reading Diagnostic Trouble Codes (DTC’s)

The provision for communicating with the ECM is the Data Link Connector (DLC) (Figure 1-1). It is part of the MEFI engine wiring harness, and is a 10-pin connector, which is electrically connected to the ECM. It is used in the assembly plant to receive information in checking that the engine is operating properly before it leaves the plant. The DTC(s) stored in the ECM’s memory can be retrieved two different ways. One way is with a Diagnostic Trouble Code (DTC) tool. The other way is through a scan tool,

A



A B C D E



K J H G F

DATA LINK CONNECTOR (DLC)



B



C



D



6-18-93

MS 13554

times. At the end of the DTC’s, the ECM will simply go back and start over with ﬂ ashing DTC 12.

Service Mode

When the DTC tool is installed at the DLC and “service mode” or “ON” is selected, the system will enter what is called the “Service Mode.” In this mode, the ECM will:

• Display a DTC 12 by ﬂ ashing the MIL, indicating that

the diagnostic system is working.

• Display any stored DTC’s by ﬂ ashing the MIL. Each

DTC will be ﬂ ashed two times, then DTC 12 will be ﬂ ashed again.

Normal Mode

When the DTC tool is in the “normal mode” or “OFF,” it has no affect on the engine operation.

MEFI On-Board Diagnostic (OBD) System Check

After the visual/physical inspection, the “On-Board Diagnostic (OBD) System Check” is the starting point for all diagnostic procedures. Refer to Diagnosis section.

The correct procedure to diagnose a problem is to follow two basic steps:

1. Are the on-board diagnostics working? This is determined by performing the “On-Board Diagnostic (OBD) System Check.” Since this is the starting point for the diagnostic procedures, always begin here. If the on-board diagnostics are not working, the OBD system check will lead to a Diagnostic Procedure in the Diagnosis section to correct the problem. If the on-board diagnostics are working properly, the next step is:

2. Is there a DTC stored? If a DTC is stored, go directly to the number DTC procedure in the Diagnosis section. This will determine if the fault is still present.

Figure 1-1 - Marine Data Link Connector (DLC)

a hand-held diagnostic scanner, plugged into the DLC. Once the DTC tool has been connected, and “service

mode” or “ON” selected, the ignition switch must be mov ed to the key “ON,” engine “OFF” position. At this point, the MIL should ﬂ ash DTC 12 two times consecutively. This would be the following flash sequence: “flash, pause, ﬂ ash-ﬂ ash, long pause, ﬂ ash, pause, ﬂ ash-ﬂ ash.” DTC 12 indicates that the ECM’s diagnostic system is operating. If DTC 12 is not indicated, a problem is present within the diagnostic system itself, and should be addressed by consulting the “On-Board Diagnostic (OBD) System Check” in the Diagnosis section.

Following the output of DTC 12, the MIL will indicate a DTC two times if a DTC is present, or it will continue to ﬂ ash DTC 12. If more than one DTC has been stored in the ECM’s memory, the DTC’s will be ﬂ ashed out from the lowest to the highest, with each DTC being ﬂ ashed two

DLC Scan Tools

The ECM can communicate a variety of information through the DLC. This data is transmitted at a high frequency which requires a scan tool for interpretation.

With an understanding of the data which the scan tool displays, and knowledge of the circuits involved, the scan tool can be very useful in obtaining information which would be more difﬁ cult or impossible to obtain with other equipment.

A scan tool does not make the use of Diagnostic Procedures unnecessary, nor do they indicate exactly where the problem is in a particular circuit. Some Diagnostic Procedures incorporate steps with the use of a scan tool (scan diagnostics), or with the DTC tool (non-scan diagnostics).

MEFI 4 - PCM

1 - 4 General Information 5.0/5.7/6.0/8.1L Scan Tool Use With Intermittents

The scan tool provides the ability to perform a “wiggle test” on wiring harnesses or components with the engine not running, while observing the scan tool display.

The scan tool can be plugged in and observed while driving the boat under the condition when the MIL turns “ON” momentarily, or when the engine driveability is momentarily poor. If the problem seems to be related to certain parameters that can be checked on the scan tool, they should be checked while driving the boat. If there does not seem to be any correlation between the problem and any speciﬁ c circuit, the scan tool can be checked on each position, watching for a period of time to see if there is any change in the readings that indicates intermittent operation.

The scan tool is also an easy way to compare the operating parameters of a poorly operating engine with those of a known good one. For example, a sensor may shift in value but not set a DTC.

The scan tool has the ability to save time in diagnosis and prevent the replacement of good parts. The key to using the scan tool successfully for diagnosis lies in the technicians ability to understand the system they are trying to diagnose, as well as an understanding of the scan tool operation and limitations. The technician should read the tool manufacturer’s operating manual to become familiar with the tool’s operation.

How Diagnostic Trouble Codes (DTC) Are Set

The ECM is programmed to receive calibrated voltage signals from the sensors. The voltage signal from the sensor may range from as low as 0.1 volt to as high as 4.9 volts. The sensor voltage signal is calibrated for engine application. This would be the sensor’s operating parameter or “window.” The ECM and sensors will be discussed further in the ECM and Sensor section.

If a sensor is within its operating or acceptable parameters (Figure 1-2), the ECM does not detect a problem. When a sensor voltage signal falls out of this “window,” the ECM no longer receives a signal voltage within the operating “window.” When the ECM does not receive the “window” voltage for a calibratible length of time, a DTC will be stored. The MIL will be illuminated and a known default value will replace the sensor value to restore engine performance.

Clearing Diagnostic Trouble Codes (NonScan)

1. Install Diagnostic Trouble Code (DTC) tool.

2. Ignition “ON,” engine “OFF.”

3. Switch DTC tool to “service mode” or “ON.”

4. Move the throttle from 0% (idle) to 100% (WOT) and

5. Switch DTC tool to “normal mode” or “OFF.” (If this

6. Turn ignition “OFF” for at least 20 seconds.

7. Ignition “ON,” engine “OFF.”

8. Switch DTC tool to “service mode” or “ON” and verify

9. If original DTC(s) are still present, check “Notice” below

10. If new DTC(s) are displayed, perform the OBD system

NOTICE: When clearing DTC’ s with or without the use of a scan tool, the ignition must be cycled to the “OFF” position or the DTC’s will not clear.

5 VOLTS

XXXXXXXXXXXXXXX DEFAULTXXXXXXXXXXX

4.6V

V O L T A G E

XXXXXXXXXXXXXXX DEFAULTXXXXXXXXXXX

0 VOLTS

Figure 1-2 - Example of Sensor Normal Operation

TYPICAL SENSOR RANGE

“WINDOW”

0.7V

6-5-93

back to 0%.

step is not performed, the engine may not start and run).

DTC 12 only. Remove DTC tool.

and repeat the DTC clearing procedure.

check.

MEFI 4 - PCM

5.0/5.7/6.0L/8.1L General Information 1 - 5 Clearing Diagnostic Trouble Codes (Scan)

1. Install scan tool.

2. Start engine.

3. Select “clear DTC’s” function.

4. Clear DTC’s.

5. Turn ignition “OFF” for at least 20 seconds.

6. Turn ignition “ON” and read DTC’s. If DTC’s are still present, check “Notice” below and repeat procedure following from step 2.

NOTICE: When clearing DTC’ s with or without the use of a scan tool, the ignition must be cycled to the “OFF” position or the DTC’s will not clear.

Non-Scan Diagnosis Of Driveability Concerns (No DTC’s Set)

If a driveability concern still exists after following the OBD system check and reviewing the Symptoms section, an out of range sensor may be suspected. Because of the unique design of the MEFI system, the ECM will replace sensed values with calibrated default values in the case of a sensor or circuit malfunction. By allowing this to occur, limited engine performance is restored until the boat is repaired. A basic understanding of sensor operation is necessary to be able to diagnose an out of range sensor.

If the sensor is out of range, but still within the operating “window” of the ECM, the prob lem will go undetected by the ECM and may result in a driveability concern.

A good example of this would be if the coolant sensor was reading incorrectly and indicating to the ECM that coolant temperature was at 50°F, but actual coolant temperature was at 150°F (Figure 1-3). This would cause the ECM to deliver more fuel than what was actually needed by the engine. This resulted in an overly rich condition, causing rough running. This condition would not have caused a DTC to set, as the ECM interprets this as within the operating “window.”

To identify a sensor that is out of range, you may unplug the sensor electrical connector while the engine is running. After about 2 minutes, the DTC for that sensor will set, illuminate the MIL, and replace the sensed value with a calibrated default value. If at that point, a noticeable performance increase is observed, the non-scan DTC table for that particular sensor may be followed to correct the problem.

NOTICE: Be sure to clear each DTC after disconnecting and reconnecting each sensor. Failure to do so may result in a misdiagnosis of the driveability concern.

Aftermarket (Add-On) Electrical And Vacuum Equipment

Aftermarket, add-on electrical and vacuum equipment is deﬁ ned as any equipment installed on a vehicle after leaving the factory that connects to the vehicles electrical or vacuum systems.

Notice: Do not attach add-on vacuum operated equipment to this engine. The use of add-on vacuum equipment may result in damage to engine components or systems.

Notice: Connect any add-on electrically operated equipment to the vehicle’s electrical system at the battery (power and ground) in order to prevent damage to the vehicle.

Add-on electrical equipment, even when installed to these strict guidelines, may still cause the powertrain system to malfunction. This may also include equipment not connected to the vehicle’s electrical system such as portable telephones and radios. Therefore, the ﬁ rst step in diagnosing any powertrain problem, is to eliminate all aftermarket electrical equipment from the vehicle. After this is done, if the problem still exists, diagnose the problem in the normal manner.

Use of Circuit Testing Tools

Do not use a test lamp in order to diagnose the engine electrical systems unless speciﬁ cally instructed by the diagnostic procedures. Use the J 35616-A connector test adapter kit whenever diagnostic procedures call for probing any connectors.

LOW TEMP - 5 VOLTS

XXXXXXXXXXXXXXX DEFAULTXXXXXXXXXXX

T

------50 -4.2V OUT OF RANGE SENSOR

E M P E R A

T U R E

------150 -1.7V ACTUAL COOLANT TEMPERATURE

XXXXXXXXXXXXXXX DEFAULTXXXXXXXXXXX

HIGH TEMP - 0 VOLTS

Figure 1-3 - Example of Shifted Sensor Operation

6-5-93

MS 13552

Tools Needed To Service The System

Refer to Special Tools in this section for engine control tools for servicing the system.

MEFI 4 - PCM

1 - 6 General Information 5.0/5.7/6.0/8.1L Service Precautions

The following requirements must be observed when working on MEFI equipped engines.

1. Before removing any ECM system component, disconnect the negative battery cable.

2. Nev er start the engine without the battery being solidly connected.

3. Never separate the battery from the on-board electrical system while the engine is running.

4. Never separate the battery feed wire from the charging system while the engine is running.

5. When charging the battery, disconnect it from the vehicle’s electrical system.

6. Ensure that all cable harnesses are connected solidly and the battery connections are thoroughly clean.

7. Never connect or disconnect the wiring harness at the ECM when the ignition is switched “ON.”

8. Before attempting any electric arc welding on the vehicle, disconnect the battery leads and the ECM connector(s).

9. When steam cleaning engines, do not direct the nozzle at any ECM system components. If this happens, corrosion of the terminals or damage of components can take place.

10. Use only the test equipment speciﬁ ed in the diagnostic procedures, since other test equipment may either giv e incorrect test results or damage good components.

11. All measurements using a multimeter must use a digital meter with a rating of 10 megaohm input impedance.

12. When a test light is speciﬁ ed, a “low-power” test light must be used. Do not use a high-wattage test light. While a particular brand of test light is not suggested, a simple test on any test light will ensure it to be safe for system circuit testing (Figure 1-4). Connect an accurate ammeter (such as the high-impedance digital multimeter) in series with the test light being tested, and power the test light ammeter circuit with the vehicle battery.

DC Amps

If the ammeter indicates the testlight is If the ammeter indicates the testlight is

safe

to use.

not safe

less

than 3/10 amp(.3A) current flow,

to use.

Figure 1-4 - Test Light Amperage Draw Test

testlight

BATTERY

I 22307

MEFI 4 - PCM

5.0/5.7/6.0L/8.1L General Information 1 - 7 Special Tools (1 of 3)

VOLTMETER - Voltage position measures magnitude of

voltage when connected in parallel to an existing circuit. A digital voltmeter with a 10 megohm input impedance is used because this type of meter will not load down the circuit and result in faulty readings. Some circuits require accurate low voltage readings because they have a very high resistance.

AMMETER - When used as an ammeter, this meter accurately measures extremely low current ﬂ ow. Refer to meter instructions for more information.

AUTO 100

OFF

1234

TRUE RMS MULTIMETER

RECORD MAX MIN AVG

5678 90

…

AC DC

m V A n F S % M k Ω Hz

4000 mV

(

Ω

• Selector must be set properly for both function and

…

range. DC is used for most measurements.

OHMMETER - Measures resistance of circuit directly in ohms. Refer to meter instructions for more information.

• OL display in all ranges indicates open circuit.

• Zero display in all ranges indicates a short circuit.

400mA MAX

FUSED

10A MAX FUSED

• An intermittent connection in a circuit may be indicated

by a digital reading that will not stabilize on the circuit.

• Range Switch - Automatic and Manual.

200ý - Reads ohms directly 2K, 20K, 200Ký - Reads ohms in thousands

J 39978

2M, 20M, 200Mý - Reads ohms in millions

➤

TACHOMETER

VACUUM PUMP WITH GAUGE (20 IN. HG. MINIMUM)

Use the gauge to monitor manifold engine vacuum and use the hand pump to check vacuum sensors, solenoids and valves.

J 23738-A

UNPOWERED TEST LIGHT

Used for checking wiring for a complete circuit, voltages and grounds.

J 34142-B

TACHOMETER

Must have inductive trigger signal pick-up.

NS 14574

MEFI 4 - PCM

1 - 8 General Information 5.0/5.7/6.0/8.1L

Special Tools (2 of 3)

METRI-PACK TERMINAL REMOVER

Used for removing 150 series Metri-Pack “pull-to-seat” terminals from connectors. Refer to wiring harness service in MEFI General Information Section for removal procedure.

J 35689

WEATHER PACK TERMINAL REMOVER

Used for removing terminals from Weather P ack connectors. Refer to wiring harness service in MEFI General Information Section for removal procedure.

J 28741-A/BT-8234-A

DIAGNOSTIC TROUBLE CODE (DTC) TOOL

A hand held diagnostic tool that plugs into the DLC connector for various diagnostics.

TA 06075

RTK0078

J 34730-2C & J 34730-350/BT 8329

RT0086

FUEL PRESSURE GAUGE

Used for checking fuel system pressure on MFI and PFI engines.

INJECTOR HARNESS TEST LIGHT

A specially designed light used to visually indicate injector electrical pulses from the ECM.

DIACOM SCAN TOOL

A hand held diagnostic tool that plugs into the DLC connector for various diagnostics. It will display various parameters.

MEFI 4 - PCM

5.0/5.7/6.0L/8.1L General Information 1 - 9 Special Tools (3 of 3)

HARNESS TEST ADAPTER KIT

Used to make electrical test connections in current W eather Pack, Metri-Pack and Micro-Pack style terminals.

J 35616

20’ DIAGNOSTIC CONNECTOR EXTENSION CABLE

Extension cable to go between the scan tool and the DLC on the engine harness.

TA 06076

FUEL LINE QUICK-CONNECT SEPARATOR

Used to release fuel line quick-connect ﬁ ttings.

J-39021

J 37088-A/BT-9171

INJECTOR TESTER

Separately energizes each injector to compare for equal fuel pressure drops over a constant time interval.

INJECTOR

VOLTS

LOWBATTERY

READYTO TEST

TESTIN PROGRESS

AMP

4AMP

2.5 AMP

PUSHTO TEST

6.5 AMP

KENT-MOORE

J 39021

TIMING LIGHT

Must have inductive signal pickup.

J 34186

MEFI 4 - PCM

1 - 10 General Information 5.0/5.7/6.0/8.1L

ABBREVIATIONS

BARO - BAROMETRIC PRESSURE BAT - BATTERY, BATTERY POSITIVE

TERMINAL, BATTERY OR SYSTEM VOLTAGE

B+ - BATTERY POSITIVE CKP - CRANKSHAFT POSITION SENSOR CKT - CIRCUIT CMP - CAMSHAFT POSITION SENSOR CONN - CONNECTOR CYL - CYLINDER DEG - DEGREES DIAG - DIAGNOSTIC DLC - DATA LINK CONNECTOR DMM - DIGITAL MULTIMETER DTC - DIAGNOSTIC TROUBLE CODE ECM - ENGINE CONTROL MODULE ECT - ENGINE COOLANT TEMPERATURE

SENSOR EEPROM - ELECTRONIC ERASABLE

PROGRAMMABLE READ ONLY MEMORY

EI - ELECTRONIC IGNITION EMI - ELECTROMAGNETIC

INTERFERENCE ENG - ENGINE GND - GROUND GPH - GALLONS PER HOUR HVS - HIGH-VOLTAGE SWITCH IAC - IDLE AIR CONTROL IAT - INTAKE AIR TEMPERATURE IC - IGNITION CONTROL

KS - KNOCK SENSOR SYSTEM KV - KILOVOLTS MAP - MANIFOLD ABSOLUTE PRESSURE MEFI - MARINE ELECTRONIC FUEL

INJECTION MFI - MULTIPORT FUEL INJECTION MIL - MALFUNCTION INDICATOR LAMP MSEC - MILLSECOND N/C - NORMALLY CLOSED N/O - NORMALLY OPEN OBD - ON-BOARD DIAGNOSTIC SYSTEM

CHECK OPT - OPTIONAL PFI - PORT FUEL INJECTION PROM - PROGRAMMABLE READ ONLY

MEMORY RAM - RANDOM ACESS MEMORY REF HI - REFERENCE HIGH REF LO - REFERENCE LOW ROM - READ ONLY MEMORY SLV - SLAVE SW - SWITCH TACH - TACHOMETER TBI - THROTTLE BODY INJECTION TERM - TERMINAL TP - THROTTLE POSITION SENSOR V - VOLTS VAC - VACUUM WOT - WIDE OPEN THROTTLE “ HG - INCHES OF MERCURY

IGN - IGNITION INJ - INJECTOR I/O - INPUT/OUTPUT kPa - KILOPASCAL

MEFI 4 - PCM

5.0/5.7/6.0L/8.1L General Information 1 - 11

T endency f or connectors to come apart due to vibration

Diagnosis

The diagnostic tables and functional checks in this manual are designed to locate a faulty circuit or component through logic based on the process of elimination. The tables are prepared with the requirement that the system functioned correctly at the time of assembly and that there are no multiple failures.

Engine control circuits contain many special design features not found in standard vehicle wiring. Environmental protection is used extensively to protect electrical contacts. Proper splicing methods must be used when necessary.

The proper operation of low amperage input/output circuits depend upon good continuity between circuit connectors. It is important before component replacement and/or during normal troubleshooting procedures that a visual inspection of any questionable mating connector is performed. Mating surfaces should be properly formed, clean and likely to make proper contact. Some typical causes of connector problems are listed below:

Improperly formed contacts and/or connector

•

housing.

Damaged contacts or housing due to improper

•

engagement.

Corrosion, sealer or other contaminants on the contact

•

mating surfaces.

Incomplete mating of the connector halves during

•

initial assembly or during subsequent troubleshooting procedures.

•

and/or temperature cycling.

Terminals not fully seated in the connector body.

•

Inadequate terminal crimps to the wire.

•

On-Board Service

Wiring Harness Service

Figure 1-5

Wiring harnesses should be replaced with proper part number harnesses. When wires are spliced into a harness, use the same gauge wire with high temperature insulation only.

With the low current and voltage levels found in the system, it is important that the best possible bond be made at all wire splices by soldering the splices as shown in Figure 1-5.

Use care when probing a connector or replacing a connector terminal. It is possible to short between opposite terminals. If this happens, certain components can be damaged. Always use jumper wires with the corresponding mating terminals between connectors for circuit checking. NEVER probe through connector seals, wire insulation, secondary ignition wires, boots, nipples or covers. Microscopic damage or holes may result in water intrusion, corrosion and/or component failure.

DRAIN WIRE

OUTER JACKET

MYLAR

1REMOVE OUTER JACKET. 2UNWRAP ALUMINUM/MYLAR TAPE. DO NOT

 REMOVE MYLAR.

3UNTWIST CONDUCTORS. STRIP INSULATION AS  NECESSARY.

DRAIN WIRE

4SPLICE WIRES USING SPLICE CLIPS AND ROSIN CORE  SOLDER. WRAP EACH SPLICE TO INSULATE.

5WRAP WITH MYLAR AND DRAIN (UNINSULATED) WIRE.

6TAPE OVER WHOLE BUNDLE TO SECURE AS BEFORE.

1LOCATE DAMAGED WIRE. 2REMOVE INSULATION AS REQUIRED.

3SPLICE TWO WIRES TOGETHER USING SPLICE  CLIPS AND ROSIN CORE SOLDER.

4COVER SPLICE WITH TAPE T O INSULA TE  FROM OTHER WIRES.

5RETWIST AS BEFORE AND TAPE WITH  ELECTRICAL TAPE AND HOLD IN PLACE.

8-24-94 RS 22186

Figure 1-5 - Wiring Harness Repair

MEFI 4 - PCM

1 - 12 General Information 5.0/5.7/6.0/8.1L Wiring Connector Service

Most connectors in the engine compartment are protected against moisture and dirt which could create oxidation and deposits on the terminals. This protection is important because of the very low voltage and current levels found in the electronic system. The connectors have a lock which secures the male and female terminals together. A secondary lock holds the seal and terminal into the connector.

When diagnosing, open circuits are often difﬁ cult to locate by sight because oxidation or terminal misalignment are hidden by the connectors. Merely wiggling a connector on a sensor, or in the wiring harness, may locate the open circuit condition. This should always be considered when an open circuit or failed sensors is indicated. Intermittent problems may also be caused by oxidized or loose connections.

Before making a connector repair, be certain of the type of connector. Some connectors look similar but are serviced differently.

Metri-Pack Series 150 Terminals

Figure 1-6

Some ECM harness connectors contain terminals called Metri-Pack (Figure 1-6). These are used at some of the sensors and the distributor connector.

Metri-Pack terminals are also called “Pull-To-Seat” terminals because, to install a terminal on a wire, the wire is ﬁ rst inserted through the seal and connector. The terminal is then crimped on the wire, and the terminal is pulled back into the connector to seat it in place.

To remove a terminal:

1. Slide the seal back on the wire.

2. Insert tool J 35689 or equivalent, as shown in Figure 1-6, to release the terminal locking tang.

3. Push the wire and terminal out through the connector. If the terminal is being reused, reshape the locking tang.

1. METRI-PACK SERIES 150 FEMALE TERMINAL.

2. LOCKING T ANG.

RS 22187

Figure 1-6 - Metri-Pack Series 150 Terminal Removal

3. TOOL J35689 OR BT-8446.

4. CONNECTOR BODY.

5. SEAL.

MEFI 4 - PCM

5.0/5.7/6.0L/8.1L General Information 1 - 13

Weather-Pack Connectors

Figure 1-7

Figure 1-7 shows a Weather-Pack connector and the tool (J 28742 or equivalent) required to service it. This tool is used to remove the pin and sleeve terminals. If terminal removal is attempted without using the special tool required, there is a good chance that the terminal will be bent or deformed, and unlike standard blade type terminals, these terminals cannot be straightened once they are bent.

Make certain that the connectors are properly seated and all of the sealing rings in place when connecting leads. The hinge-type ﬂ ap provides a secondary locking feature for the connector. It improves the connector reliability by retaining the terminals if the small terminal lock tangs are not positioned properly. Weather-Pack connections cannot be replaced with standard connections.

MALE CONNECTOR BODY

1. OPEN SECONDARY LOCK HINGE ON CONNECTOR

2. REMOVE TERMINAL USING TOOL

TERMINAL REMOVAL TOOL J 28742, J 38125-10 OR BT-8234-A

3. CUT WIRE IMMEDIATELY BEHIND CABLE SEAL

SEAL

FEMALE CONNECTOR BODY

PUSH TO RELEASE

WIRE

4. REPLACE TERMINAL A. SLIP NEW SEAL ONTO WIRE B. STRIP 5mm (.2") OF INSULATION FROM WIRE C. CRIMP TERMINAL OVER WIRE AND SEAL

SEAL

5. PUSH TERMINAL INTO CONNECTOR UNTIL LOCKING TANGS ENGAGE

6. CLOSE SECONDARY LOCK HINGE

RS 22188

Figure 1-7 - Weather-Pack Terminal Repair

MEFI 4 - PCM

1 - 14 General Information 5.0/5.7/6.0/8.1L

Micro-Pack 100/W Series Connectors

Figure 1-8

The harness connectors used with the ECM “J1” and “J2” connectors are Micro-Pack 100/W Series. It is used for its ruggedized construction, capable of carrying more current and provides good sealing ability. The connector is made up of ﬁ ve different parts (refer to Figure 1-8 View A): Str ain Relief (1), Seal (2), Connector (3), Index Cover (4) and Ter minals (not shown).

Remove or Disconnect

1. Negative battery cable.

2. Connector from ECM by lifting up locking tab with thumb and pulling on connector body.

Inspect

Check strain relief for being cracked or locking tab

•

damaged.

Check index cover for being cracked.

•

Check seal for being torn, twisted or out of shape from

•

improper installation.

Check terminals for being corroded, out of position,

•

bent or stretched out.

Use a wire gauge .038 for checking terminal

–

internal ﬁ t. Wire gauge should slide with smooth feel and not be loose.

Notice: If you are only going to clean terminals, complete disassembly is not necessary. Remove index cover from the connector by pushing on Tab C on both sides and sliding off cover. Care m ust be tak en not to mov e terminals out of their position. The index cover locks the terminals in position. If repair or replacement of parts is needed, DO NOT remove index cover at this time.

3. With a small screwdriver, move Tabs A on strain relief (1) to unlock position.

4. Open strain relief as shown in View B.

5. Release Tabs B (View C) on connector (3) by pushing inward with both thumbs or small screwdriver.

6. Push Tabs B through strain relief (1) with thumbs or small screwdriver while in released position.

Important

Where there are not wires in strain relief, small plugs

•

are installed. DO NO T lose the plugs, they are important to help keep connector assembly sealed.

7. Remove plugs where there are not any wires.

8. Slide strain relief off of seal and back on wires.

9. Slide seal off of connector and back on wires.

Important

To ensure proper engine operation after repair of

•

connector assembly , wires must be in proper connector location. Before removing index cover, note if there are any wires of the same color. Mark these wires from the location that they were remov ed. For the remaining wires, their location can be found by ref erring to “Wiring Diagrams” in the Diagnosis section. The strain relief is numbered for identifying wire location.

10. Index cover (4) by pushing in on Tabs C with a small screwdriver.

11. Ter minals by pulling out of connector.

12. Seal (2) from wires.

13. Strain relief (1) from wires.

Clean and Inspect

Terminals for corrosion.

•

– Use spray electrical contact cleaner.

Loose crimps on terminals.

•

Broken wires at terminals.

•

Notice: For terminal replacement, refer to instructions found with terminal repair kit and crimper tool.

Install or Connect

1. Align index cover (4) on connector (3) and lock into position. Make sure Tabs C are locked.

2. Align seal (2) on connector (3) and slide all the way on.

DO NOT install strain relief (1) onto connector (3)

•

yet.

3. One wire with terminal installed, through strain relief (1) in location that it was removed.

Start with the lowest numbered wire position for

•

that connector.

4. Terminal through seal (2), connector (3) and into inde x cover (4) until it locks in place.

5. Remaining wires one at a time per same method.

• Keep wires straight.

DO NOT kink wires.

•

6. Strain relief (1) onto seal (2) and connector (3).

7. Lock Tabs B into strain relief (1).

8. Plugs into strain relief (1) where there are not any wires.

9. Fold strain relief (1) together and lock Tabs A.

10. Connector assembly to ECM.

11. Negative battery cable.

MEFI 4 - PCM

5.0/5.7/6.0L/8.1L General Information 1 - 15

TAB B

TAB C

FIGURE A - EXPLODED VIEW OF CONNECTOR ASSEMBLY

1 STRAIN RELIEF 2 SEAL

TAB A

FIGURE B - STRAIN RELIEF CLOSED

TAB B

3 CONNECTOR 4 INDEX COVER

TAB A

21 3 4 5 6 7 8 9 10111213141516

1817 1920212223242526272829303132

TAB A

TAB B

FIGURE C - STRAIN RELIEF OPENED

PS 19745

Figure 1-8 - Micro-Pack 100/W Series

MEFI 4 - PCM

1 - 16 General Information 5.0/5.7/6.0/8.1L

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MEFI 4 - PCM

5.0/5.7/6.0L/8.1L ECM and Sensors 2 - 1

Marine Electronic Fuel Injection (MEFI) Section 2 Engine Control Module (ECM) and Sensors

This section will describe the function of the Engine Control Module (ECM) and the sensors. The section explains how voltages reflect the inputs and outputs of the ECM. The sensors are described how they operate and how to replace them.

Contents

General Description .............................................Page 2

Computers and Voltage Signals.......................Page 2

Analog Signals.................................................Page 2

Three-Wire Sensors ..................................Page 2

Two-Wire Sensors .....................................Page 2

Digital Signals..................................................Page 3

Switch Types..............................................Page 3

Pulse Counters..........................................Page 3

Engine Control Module (ECM).........................Page 4

ECM Function............................................Page 4

Memory .....................................................Page 4

ROM..........................................................Page 4

RAM...........................................................Page 4

EEPROM...................................................Page 4

Speed Density System ....................................Page 5

Speed........................................................Page 5

Density.......................................................Page 5

ECM Inputs and Sensor Descriptions..............Page 5

Input Components............................................Page 5

Output Components.........................................Page 5

MEFI Inputs and Outputs ..........................Page 6

Engine Coolant Temperature (ECT)

Sensor.......................................................Page 7

Manifold Absolute Pressure (MAP)

Sensor.......................................................Page 7

Throttle Position (TP) Sensor....................Page 8

Intake Air Temperature (IAT) Sensor.........Page 8

Ignition Control (IC) Reference..................Page 8

Knock Sensor............................................Page 9

Discrete Switch Inputs...............................Page 9

Diagnosis ............................................................Page 10

Engine Control Module (ECM).......................Page 10

On-Board Service ...............................................Page 10

Engine Control Module (ECM)

Replacement..................................................Page 10

System Relay.................................................Page 11

Fuel Pump Relay ...........................................Page 11

Starter Relay..................................................Page 11

Engine Coolant Temperature (ECT)

Sensor............................................................Page 12

Manifold Absolute Pressure (MAP)/Intake Air

Temperature (IAT) Sensor (5.0/5.7L).............Page 13

Manifold Absolute Pressure (MAP)

Sensor (6.0/8.1L)...........................................Page 14

Throttle Position (TP) Sensor.........................Page 16

Idle Air Control (IAC) Valve............................Page 17

Knock Sensor (KS) (5.0/5.7L)........................Page 18

Knock Sensors (KS) (6.0L)............................Page 18

Torque Speciﬁ cations ........................................Page 20

MEFI 4 - PCM

2 - 2 ECM and Sensors 5.0/5.7/6.0/8.1L

General Description

The Marine Electronic Fuel Injection (MEFI) system is equipped with a computer that provides the operator with state-of-the-art control of fuel and spark delivery. Before we discuss the computers on the Marine applications, let’s discuss how computers use voltage to send and receive information.

Computers and Voltage Signals

Voltage is electrical pressure. Voltage does not flow through circuits. Instead, voltage causes current. Current does the real work in electrical circuits. It is current, the ﬂ ow of electrically charged particles, that energizes solenoids, closes relays and illuminates lamps.

Besides causing current ﬂ ow in circuits, voltage can be used as a signal. Voltage signals can send information by changing levels, changing waveform (shape) or changing the speed (frequency( at which the signal switches from one level to another. Computers use voltage signals to communicate with one another. The different circuits inside computers also use voltage signals to talk to each other.

There are two kinds of voltage signals, analog and digital. Both of these are used in computer systems. It is important to understand the difference between them and the different ways they are used.

Analog Signals

An analog signal is continuously variable. This means that the signal can be any voltage within a certain range.

An analog signal usually gives information about a condition that changes continuously over a certain range. For example, in a marine engine, temperature is usually provided by an analog signal. There are two general types of sensors that produce analog signals, the 3-wire and the 2-wire sensors.

Three-Wire Sensors

Figure 2-1 shows a schematic representation of a 3-wire sensor. All 3-wire sensors have a reference voltage, a ground and a variable “wiper.” The lead coming off of the “wiper” will be the signal to the Engine Control Module (ECM). As this “wiper” position changes, the signal voltage to the ECM also changes.

ECM

TYPICAL SENSOR

Figure 2-1 - Three-Wire Sensors

VOLTAGE OUT

SIGNAL INPUT

4-24-91

MS 11697

Two-Wire Sensors

Figure 2-2 shows a schematic representation of a 2-wire sensor. This sensor is basically a variable resistor in series with a known-ﬁ xed resistor within the ECM. By knowing the values of the input voltage and the v oltage drop across the known resistor, the value of the variable resistor can be determined. The variable resistors that are commonly used are called thermistors. A thermistor’s resistance varies with temperature.

ECM

TYPICAL SENSOR

SENSOR SIGNAL

MEFI 4 - PCM

SENSOR GROUND

4-24-91

MS 11698

Figure 2-2 - Two-Wire Sensors

5.0/5.7/6.0L/8.1L ECM and Sensors 2 - 3

Digital Signals

Digital signals are also variable, but not continuously. They can only be represented by distinct voltages within a range . For example, 1V, 2V or 3V would be allowed, but 1.27V or

2.56V would not. Digital signals are especially useful when the information can only refer to two conditions: “YES” and “NO,” “ON” and “OFF” or “HIGH” and “LOW.” This would be called a digital binary signal. A digital binary signal is limited to two voltage lev els . One lev el is a positiv e voltage , the other is no voltage (zero volts). As y ou can see in Figure 2-3, a digital binary signal is a square wave.

The ECM uses digital signals in a code that contains only ones and zeros. The high voltage of the digital signal represents a one (1), and no voltage represents a zero (0). Each “zero” and each “one” is called a bit of information, or just a “bit.” Eight bits together are called a “word.” A word, therefore, contains some combination of eight binary code bits.

Binary code is used inside the ECM and between a computer and any electronic device that understands the code. By stringing together thousands of bits, computers can communicate and store an inﬁ nite varieties of information. To a computer that understands binar y, 11001011 might mean that it should turn an output device “ON” at slow speed. Although the ECM uses 8-bit digital codes internally and when talking to another computer, each bit can have a meaning.

Switch T ypes

Switched inputs (also known as discretes) to the ECM can cause one bit to change, resulting in information being communicated to the ECM. Switched inputs can come in two types: “pull-up” and “pull-down” types. Both types will be discussed.

With “pull-up” type switch, the ECM will sense a voltage when the switch is CLOSED. With “pull-down” type switch, the ECM will sense a voltage when the switch is OPEN.

Pulse Counters

For the ECM to determine frequency information from a switched input, the ECM must measure the time between the voltage pulses. As a number of pulses are recorded in a set amount of time, the ECM can calculate the frequency. The meaning of the frequency number can have any number of meanings to the ECM.

An example of a pulse counter type of input is the Crankshaft Position (CKP) sensor input. The ECM can count a train of pulses, a given number of pulses per engine revolution. In this way, the ECM can determine the RPM of the engine.

V O L T A G E

DIGITAL BINARY SIGNAL

TIME

4-18-91

MS 11696

Figure 2-3 - Digital Voltage Signal

MEFI 4 - PCM

2 - 4 ECM and Sensors 5.0/5.7/6.0/8.1L

Engine Control Module (ECM)

The Engine Control Module (ECM), located on the engine, is the control center of the fuel injection system. It controls the following:

• Fuel control circuit

• Ignition control circuit

• Idle Air Control (IAC)

• Knock Sensor (KS) system

• On-board diagnostics for engine functions

It constantly looks at the information from various sensors, and controls the systems that affect engine performance. The ECM also performs the diagnostic function of the system. It can recognize operational problems, alert the operator through the MIL (Malfunction Indicator Lamp) and store diagnostic trouble codes, or logged warnings, which identify the problem areas to aid the technician in making repairs. Refer to General Information section for more information on using the diagnostic function of the ECM.

ECM Function

The ECM supplies either 5 or 12 volts to power various sensors or switches. This is done through resistances in the ECM which are so high in value that a test light will not light when connected to the circuit. In some cases, even an ordinary shop voltmeter will not give an accurate reading because its resistance is too low. Therefore, a digital voltmeter with at least 10 megohms input impedance is required to ensure accurate voltage readings. Tool J 39978 meets this requirement.

The ECM controls output circuits such as the injectors, IAC, relays, etc. by controlling the ground or power feed circuit.

Memory

There are three types of memory storage within the ECM. They are ROM, RAM and EEPROM.

ROM

Read Only Memory (ROM) is a permanent memory that is physically soldered to the circuit boards within the ECM. The ROM contains the overall control programs. Once the ROM is programmed, it cannot be changed. The ROM memory is non-erasable, and does not need power to be retained.

RAM

Random Access Memory (RAM) is the microprocessor “scratch pad.” The processor can write into, or read from this memory as needed. This memory is erasable and needs a constant supply of voltage to be retained. If the voltage is lost, the memory is lost.

EEPROM

The Electronically Erasable Programmable Read Only Memory (EEPROM) is a permanent memory that is physically soldered within the ECM. The EEPROM contains program and calibration information that the ECM needs to control engine operation.

The EEPROM is not replaceable. If the ECM is replaced, the new ECM will need to be programmed by the engine manufacturer with the calibration inf ormation that is speciﬁ c to each marine application.

MEFI 4 - PCM

J2J1

MEFI3004

Figure 2-4 - Engine Control Module (ECM)

5.0/5.7/6.0L/8.1L ECM and Sensors 2 - 5

Speed Density System

The Marine Electronic Fuel Injection (MEFI) system is a speed and air density system. The system is based on “speed density” fuel management.

Sensors provide the ECM with the basic information for the fuel management portion of its operation. Signals to the ECM establish the engine speed and air density factors.

Speed

The engine speed signal comes from the CKP sensor to the ECM. The ECM uses this information to determine the “speed” or RPM factor for fuel and spark management.

Density

One particular sensor contributes to the density factor, the Manifold Absolute Pressure (MAP) sensor. The MAP sensor is a 3-wire sensor that monitors the changes in intake manifold pressure which results from changes in engine loads. These pressure changes are supplied to the ECM in the form of electrical signals.

As intake manifold pressure increases, the vacuum decreases. The air density in the intake manifold also increases, and additional fuel is needed.

The MAP sensor sends this pressure information to the ECM, and the ECM increases the amount of fuel injected, by increasing the injector pulse width. As manifold pressure decreases, the vacuum increases, and the amount of fuel is decreased.

These two inputs, MAP and RPM, are the major determinants of the air/fuel mixture delivered by the fuel injection system. The remaining sensors and switches provide electrical inputs to the ECM, which are used for modiﬁ cation of the air/fuel mixture, as well as for other ECM control functions, such as idle control.

ECM Inputs and Sensor Descriptions

Figure 2-5 lists the data sensors, switches, and other inputs used by the ECM to control its various systems. Although we will not cover them all in great detail, there will be a brief description of each.

Input Components

The ECM monitors the input components for circuit continuity and out-of-range values. This includes performance checking. Performance checking refers to indicating a fault when the signal from a sensor does not seem reasonable, such as a throttle position (TP) sensor that indicates high throttle position at low engine loads or MAP voltage. The input components may include, but are not limited to, the following sensors:

• Intake air temperature (IAT) sensor (5.0/5.7L only)

• Crankshaft position (CKP) sensor

• Camshaft position (CMP) sensor

• Knock sensor(s) (KS)

• Throttle position (TP) sensor

• Engine coolant temperature (ECT) sensor

• Manifold absolute pressure (MAP) sensor

Output Components

Diagnose the output components for the proper response to ECM commands. Components where functional monitoring is not feasible, will be monitored for circuit continuity and out-of-range values, if applicable.

Output components to be monitored include, but are not limited to, the following circuits:

• The malfunction indicator lamp (MIL) control

• The check gauges lamp control

• The general warning 2 (low oil pressure) lamp control

MEFI 4 - PCM

2 - 6 ECM and Sensors 5.0/5.7/6.0/8.1L

MEFI INPUTS AND OUTPUTS

INPUTS

BATTERY 12V

IGNITION 12V

CRANKSHAFT POSITION SENSOR (RPM)

CAMSHAFT POSITION SENSOR

THROTTLE POSITION (TP) SENSOR

MANIFOLD ABSOLUTE PRESSURE(MAP)

(TYPICAL)

L E C T R

O N

OUTPUTS

FUEL INJECTORS

MULTIPLE IGNITION CONTROLS (IC)

FUEL PUMP RELAY

IDLE AIR CONTROL (IAC)

OPERATOR INFORMATION LAMPS/BUZZERS

SERIAL DATA (ECM COMMUNICATION)

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

INTAKE AIR TEMPERATURE (IAT) (5.0/5.7L only)

KNOCK SENSOR 1

KNOCK SENSOR 2 (6.0/8.1L only)

DIAGNOSTIC ENABLE

GENERAL WARNING 2 (OIL PRESSURE)

C O N

R O

M O D U

L E

V- REFERENCE (5 VOLT OUTPUT TO SENSORS)

MALFUNCTION INDICATOR LAMP (MIL)

DEPSPOWER (12 VOLT OUTPUT TO SENSORS)

Figure 2-5 - ECM Inputs and Outputs (Typical)

MEFI 4 - PCM

2-13-04

MS 11699

5.0/5.7/6.0L/8.1L ECM and Sensors 2 - 7

Engine Coolant Temperature (ECT) Sensor

The engine coolant temperature (ECT) sensor is a thermistor (a resistor which changes value based on temperature) mounted in the engine coolant stream. Low coolant temperature produces a high resistance (100,000 ohms at -40°C/-40°F) while high temperature causes low resistance (70 ohms at 130°C/266°F).

The ECM supplies a 5 volt signal to the ECT sensor through a resistor in the ECM and measures the voltage. The voltage will be high when the engine is cold, and low when the engine is hot. By measuring the v oltage, the ECM calculates the engine coolant temperature. Engine coolant temperature affects most systems the ECM controls.

A hard fault in the engine coolant sensor circuit should set DTC 14 or DTC 15; an intermittent fault may or may not set a DTC. The DTC “Diagnostic Aids” also contains a chart to check for sensor resistance values relative to temperature.

The ECM supplies a 5 volt reference voltage to the MAP sensor. As the manifold pressure changes, the electrical resistance of the MAP sensor also changes. By monitoring the sensor output voltage, the ECM knows the manifold pressure. A higher pressure, low vacuum (high voltage) requires more fuel. A lower pressure, high vacuum (low voltage) requires less fuel. The ECM uses the MAP sensor to control fuel delivery and ignition timing. A failure in the MAP sensor circuit should set a DTC 33 or DTC 34.

1HARNESS CONNECTOR 2LOCKING TAB 3SENSOR

Figure 2-6 - Engine Coolant Temperature (ECT) Sensor



8-24-94

RS 22189

Manifold Absolute Pressure (MAP) Sensor

The Manifold Absolute Pressure (MAP) sensor is a pressure transducer that measures the changes in the intake manifold pressure. The pressure changes as a result of engine load and speed change, and the MAP sensor converts this into a voltage output.

A closed throttle on engine coastdown would produce a relatively low MAP output voltage, while a wide open throttle would produce a high MAP output voltage. This high output voltage is produced because the pressure inside the manifold is almost the same as outside the manifold, so you measure almost 100% of outside air pressure. MAP is the opposite of what you would measure on a vacuum gauge. When manifold pressure is high, vacuum is low, causing a high MAP output voltage. The MAP sensor is also used to measure barometric pressure under certain conditions, which allows the ECM to automatically adjust for different altitudes.

Figure 2-7 - Manifold Absolute Pressure (MAP) Sensor/

Intake Air Temperature (IAT) Sensor

(Used On 5.0/5.7L Engines)

I 22312

Figure 2-8 - Manifold Absolute Pressure (MAP) Sensor

(Used On 6.0/8.1L Engines)

MEFI 4 - PCM

2 - 8 ECM and Sensors 5.0/5.7/6.0/8.1L

Throttle Position (TP) Sensor

The Throttle Position (TP) sensor is a potentiometer connected to the throttle shaft on the throttle body. By monitoring the voltage on the signal line, the ECM calculates throttle position. As the throttle valve angle is changed (accelerator pedal moved), the TP sensor signal also changes. At a closed throttle position, the output of the TP sensor is low. As the throttle valve opens, the output increases so that at Wide Open Throttle (WOT), the output voltage should be above 4 volts.

The ECM calculates fuel delivery based on throttle valve angle (driver demand). A broken or loose TP sensor may cause intermittent bursts of fuel from an injector and unstable idle because the ECM thinks the throttle is moving. A hard failure in the TP sensor circuit should set either a DTC 21 or DTC 22. Once a DTC is set, the ECM will use a calibratible default value for throttle position and some engine performance will return.

Intake Air Temperature (IAT) Sensor (5.0/5.7L)

The Intake Air Temperature (IAT) sensor is a thermistor which changes value based on the temperature of air entering the engine (Figure 2-12). Low temperature produces a high resistance (100,000 ohms at -40°C/-40°F) while high temperature causes low resistance (70 ohms at 130°C/266°F).

The ECM supplies a 5 volt signal to the sensor through a resistor in the ECM and measures the voltage. The voltage will be high when the incoming air is cold, and low when the incoming air is hot. By measuring the voltage, the ECM calculates the incoming air temperature. The IAT sensor signal is used to determine spark timing based on incoming air density.

The scan tool displays temperature of the air entering the engine, which should read close to ambient air temperature when engine is cold, and rise as engine compartment temperature increases. If the engine has not been run for several hours (overnight), the IAT sensor and ECT sensor temperatures should read close to each other. A failure in the IAT sensor circuit should set DTC 23 or DTC 25.

1 THROTTLE POSITION (TP) SENSOR  2 TP SENSOR ATTACHING SCREW

Figure 2-10 - Throttle Position (TP) Sensor (Typical)

C B

CONTROL MODULE

RS 22191

Figure 2-12 - Manifold Absolute Pressure (MAP) Sensor/

Intake Air Temperature (IAT) Sensor

(Used On 5.0/5.7L Engines)

Ignition Control (IC) Reference

The Ignition Control (IC) reference (RPM signal) is supplied to the ECM by way of the crankshaft position sensor. This pulse counter type input creates the timing signal for the pulsing of the fuel injectors, as well as the IC functions. This signal is used for a number of control and testing functions within the ECM.

1 THROTTLE POSITION (TP) SENSOR  2 THROTTLE VALVE

Figure 2-11 - Throttle Position (TP) Sensor (Typical)

MEFI 4 - PCM

RS 22192

5.0/5.7/6.0L/8.1L ECM and Sensors 2 - 9

Knock Sensor (KS) System Description

Purpose:

To control spar k knock (detonation), a knock sensor (KS) system is used. This system is designed to retard spark timing when excessive spark knock is detected in the engine. The KS system allows the engine to use maximum spark advance for optimal driveability and fuel economy under all operating conditions.

Operation:

The ECM uses a knock sensor(s) to detect abnormal vibration in the engine (detonation/spark knock). Mounted on the engine block, the knock sensor(s) produces an AC voltage signal at all engine speeds and loads. The ECM then adjusts the spar k timing based on the amplitude and frequency of the KS signal. The ECM uses the KS signal to calculate an average voltage. Then, the ECM assigns a voltage range above and below the average voltage value. The ECM checks the KS and related wiring by comparing the actual knock signal to the assigned voltage range. A normal KS signal should vary outside the assigned voltage range as shown in the NORMAL KS ﬁ gure. If the ECM detects a KS signal within the assigned voltage range as shown in the ABNORMAL KS ﬁ gure, the applicable DTC will set.

Abnormal Knock Sensor Signal

Legend

1. Upper fail region

2. Knock sensor calculated average

3. Knock sensor signal

4. Lower fail region

245257

Normal Knock Sensor Signal

245253

Discrete Switch Inputs

Several discrete switch inputs are utilized by the MEFI system to identify abnormal conditions that may affect engine operation. Pull-up and pull-down type switches are currently used in conjunction with the ECM to detect critical conditions to engine operation.

If a switch changes states from its normal at rest position, that is, normally closed to open, or normally open to closed, the ECM senses a change in voltage and responds by entering Power reduction mode.

This engine protection feature allows the operator normal engine operations up to 2500 RPM, but disables half the fuel injectors until the engine drops below 1200 RPM. Then normal engine operation is restored until the RPM limit is exceeded. This feature allows the operator a safe maneuvering speed while removing the possibility of high RPM engine operation until the problem is corrected.

Switches that may be used with the MEFI system to detect critical engine operation parameters are:

• Oil Pressure

MEFI 4 - PCM

2 - 10 ECM and Sensors 5.0/5.7/6.0/8.1L

Diagnosis

Engine Control Module (ECM)

To read and clear diagnostic trouble codes, use a scan tool or Diagnostic Trouble Code (DTC) tool.

Important: Use of a scan tool is recommended to clear diagnostic trouble codes from the ECM memory . Diagnostic trouble codes can also be cleared by using the DTC tool.

Since the ECM can have a failure which may affect more than one circuit, following the diagnostic procedures will determine which circuit has a problem and where it is.

If a diagnostic procedure indicates that the ECM connections or ECM is the cause of a problem and the ECM is replaced, but does not correct the problem, one of the following may be the reason:

• Check for good ECM power and grounds.

• There is a problem with the ECM terminal connections.

The diagnostic table will say ECM connections or ECM. The terminals may have to be removed from the connector in order to check them properly.

• EEPROM program is not correct for the application.

Incorrect components may cause a malfunction and may or may not set a DTC.

• The problem is intermittent. This means that the

problem is not present at the time the system is being checked. In this case, refer to the Symptoms portion of the manual and make a careful physical inspection of all portions of the system involved.

• Shorted relay coil or harness. Relays are turned

“ON” and “OFF” by the ECM using internal electronic switches called drivers. A shorted relay coil or harness may not damage the ECM but will cause the relay to be inoperative.

On-Board Service

Engine Control Module (ECM) Replacement

Notice: When replacing the ECM, the ignition must be “OFF” and disconnect the battery before disconnecting or reconnecting the ECM “J1” and “J2” connectors to prevent internal damage to the ECM.

Notice: T o prev ent possible electrostatic discharge damage to the ECM, do not touch the connector pins. The ECM is an electrical component. Do Not soak in any liquid cleaner or solvent, as damage may result.

Remove or Disconnect

1. Negative battery cable.

2. “J1” and “J2” connectors from ECM.

3. The ECM mounting screws.

4. ECM from mounting bracket.

Important

• Make sure the new ECM has the same part number

and service number as the old ECM, to insure proper engine performance.

Install or Connect

1. New ECM to mounting bracket.

2. The ECM mounting screws. Torque to 10-14 N•m (88-124 lb in).

3. “J1” and “J2” connectors to ECM.

4. Negative battery cable.

MEFI 4 - PCM

J2J1

MEFI3004

Figure 2-13 - Engine Control Module (ECM)

+ 307 hidden pages

PleasureCraft Engine Group 5.0L, 6.0L, 8.1L, 5.7L, MEFI 4 5.0L Diagnostic Manual

Specifications and Main Features

Frequently Asked Questions

User Manual