AEM 30-6905 Universal Programmable EMS-4 User Manual
!
WARNING:
This installation is not for the tuning novice nor the PC illiterate!
Use this system with EXTREME caution! The EMS-4 allows for
total flexibility in engine tuning. Misuse of this product WILL
destroy your engine!
Installation of the EMS-4 must be performed by a qualified EFI
technician familiar with EFI sensors, actuators and wiring.
You should also visit the AEM EMS Tech Forum at
http://www.aempower.com
NOTE: AEM holds no responsibility for any engine damage that
results from the misuse of this product!
INSTALLATION AND TUNING GUIDE FOR:
EMS P/N 30-6905
EMS-4
PROGRAMMABLE ENGINE MANAGEMENT SYSTEM
This product is legal in California for racing vehicles only and should never be used on public
highways.
2205 W. 126TH STREET, UNIT A HAWTHORNE CA 90250
AEM PERFORMANCE ELECTRONICS
PHONE: 310-484-2322 FAX: 310-484-0152
http://www.aemelectronics.com
Page 1 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Revision History
Version
Date
Modified Sections
Description
Initial Release, 1.0
12/27/10
1.1
12/28/10
Typical Idle Setup
Tab
Injectors section
Added example calculations
for Idle Frequency Settings
Clarified a section reference
1.2
12/28/10
Injection Phasing
Coil Phasing
Added details on Injector
Advance table
Added details on alternative
firing order setups
1.3
12/30/10
EMS-4 GPIOs
Added additional details to
example setups
1.4
1/4/11
Timing Pattern
Basics
Corrected error in diagram
1.5
1/10/11
Various
Fixed several minor
typographical errors
1.6
2/10/11
Internal Logging
Clarifications
1.7
3/23/11
Advanced Tuning
Added Switched Ign
Retard/Cut documentation
Page 2 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Table of Contents
General Information ...................................................................................................................... 6
Electronics Warranty ..................................................................................................................... 6
Part 1 – EMS-4 Installation ........................................................................................................... 7
EMS-4 Basic Specifications ...................................................................................................... 7
Wire Harness Options ............................................................................................................... 7
ECU Terminations with Mini Harness, P/N 30-2905-0 ......................................................... 10
Electronic Wiring Conventions ............................................................................................. 16
Grounding ............................................................................................................................ 17
Power Requirements of the AEM EMS ................................................................................ 17
Use of Relays to Control Ancillary Devices ......................................................................... 17
Installation with Full Harness, P/N 30-3905-96 ....................................................................... 18
USB Connector .................................................................................................................... 18
CAN Connector .................................................................................................................... 19
Injectors ............................................................................................................................... 19
Coils / Electronic Ignition System Basics ............................................................................. 21
TPS (Throttle Position Sensor) ............................................................................................ 26
MAP Sensor ......................................................................................................................... 26
Air Temp Sensor .................................................................................................................. 27
Water Temp Sensor ............................................................................................................. 28
Crank Sensor ....................................................................................................................... 29
Cam Sensor ......................................................................................................................... 33
Vehicle Speed Sensor (VSS) ............................................................................................... 34
Part 2 – AEM Tuner .................................................................................................................... 37
Software Installation ................................................................................................................ 37
AEM Tuner .............................................................................................................................. 39
Basic Terminology ............................................................................................................... 40
Menu Items .......................................................................................................................... 42
Editing EMS Calibration Files .................................................................................................. 77
Editing Options Displays ...................................................................................................... 77
Editing 2D Table Displays .................................................................................................... 81
Editing Channel Displays ..................................................................................................... 89
Editing 3D Map Displays ...................................................................................................... 90
Page 3 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Part 3 – Tuning Guide ................................................................................................................. 98
Background ............................................................................................................................. 98
Fuel Tuning General Concepts ............................................................................................ 98
Spark Tuning General Concepts ......................................................................................... 99
Calibration Setup ................................................................................................................... 100
Base Calibrations ............................................................................................................... 100
Timing Pattern Basics ........................................................................................................ 101
Fuel Phasing and Injector Setup ........................................................................................ 104
A more complex example .................................................................................................. 106
Ignition Phasing and Coil Dwell Discussion ....................................................................... 107
Set up RPM and Load axes ............................................................................................... 114
EFI Sensors ........................................................................................................................... 115
TPS (Throttle Position Sensor) .......................................................................................... 115
MAP (Manifold Pressure Sensor) ...................................................................................... 116
Air Temperature Sensor .................................................................................................... 119
Water Temp Sensor ........................................................................................................... 120
O2 (Oxygen) Sensors ......................................................................................................... 120
Knock Sensor .................................................................................................................... 125
Sensor Calibration ............................................................................................................. 126
Fuel System Setup ................................................................................................................ 134
Fuel Pump Setup ............................................................................................................... 134
Fuel Pump Sizing ............................................................................................................... 135
Fuel Pump Location ........................................................................................................... 136
Fuel Hoses and Routing .................................................................................................... 136
Fuel Delivery Hose Sizes ................................................................................................... 137
Fuel Filter and Fuel Rail ..................................................................................................... 137
Fuel Pressure Regulator and Pulse Dampener ................................................................. 139
Basic Tuning .......................................................................................................................... 142
Timing Pickup Confirmation ............................................................................................... 142
Noise .................................................................................................................................. 145
Ignition Synchronization ..................................................................................................... 146
Crank Fuel & Engine Start ................................................................................................. 148
Idle Air Control ................................................................................................................... 150
Page 4 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Fuel Tuning ........................................................................................................................ 158
Acceleration/Deceleration Modifiers for Engine Fueling .................................................... 176
Ignition Tuning Theory ....................................................................................................... 182
Ignition Map ....................................................................................................................... 193
Ignition Trims ..................................................................................................................... 193
Vehicle Speed .................................................................................................................... 197
EMS-4 GPIOs .................................................................................................................... 199
Data logging ....................................................................................................................... 209
Advanced Tuning .................................................................................................................. 216
Boost Control ..................................................................................................................... 216
Knock Control .................................................................................................................... 231
Traction Control ................................................................................................................. 233
2Step Rev Limiter .............................................................................................................. 242
O2 Feedback ..................................................................................................................... 245
Nitrous Control ................................................................................................................... 252
Anti-Lag ............................................................................................................................. 256
Analog Input Switch ........................................................................................................... 259
Staged Injection ................................................................................................................. 260
Switched Ignition Retard/Cut ............................................................................................. 266
Glossary of Terms ................................................................................................................. 269
Index ...................................................................................................................................... 278
Page 5 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
General Information
READ AND UNDERSTAND THESE INSTRUCTIONS BEFORE ATTEMPTING TO INSTALL THIS
PRODUCT. VISIT THE AEM PERFORMANCE ELECTRONICS TECH SUPPORT FORUM AT
http://forum.aempower.com/forum/index.php ALL CURRENT SOFTWARE AND DOCUMENTATION
IS AVAILABLE ON THIS FORUM.
YOU MAY ALSO CONTACT AEM PERFORMANCE ELECTRONICS TECH SUPPORT AT 1-800-423-
0046 IF YOU HAVE ANY QUESTIONS.
Electronics Warranty
Advanced Engine Management Inc. warrants to the consumer that all AEM Electronics products
will be free from defects in material and workmanship for a period of twelve months from date of
the original purchase. Products that fail within this 12-month warranty period will be repaired or
replaced when determined by AEM that the product failed due to defects in material or
workmanship. This warranty is limited to the repair or replacement of the AEM part. In no event
shall this warranty exceed the original purchase price of the AEM part nor shall AEM be
responsible for special, incidental or consequential damages or cost incurred due to the failure
of this product. Warranty claims to AEM must be transportation prepaid and accompanied with
dated proof of purchase. This warranty applies only to the original purchaser of product and is
non-transferable. All implied warranties shall be limited in duration to the said 12-month
warranty period. Improper use or installation, accident, abuse, unauthorized repairs or
alterations voids this warranty. AEM disclaims any liability for consequential damages due to
breach of any written or implied warranty on all products manufactured by AEM. Warranty
returns will only be accepted by AEM when accompanied by a valid Return Merchandise
Authorization (RMA) number. Product must be received by AEM within 30 days of the date the
RMA is issued.
Please note that before AEM can issue an RMA for any electronic product, it is first necessary
for the installer or end user to contact the tech line at 1-800-423-0046 to discuss the problem.
Most issues can be resolved over the phone. Under no circumstances should a system be
returned or a RMA requested before the above process transpires.
AEM will not be responsible for electronic products that are installed incorrectly, installed in a
non-approved application, misused, or tampered with.
Any AEM electronics product can be returned for repair if it is out of the warranty period. There
is a minimum charge of $50.00 for inspection and diagnosis of AEM electronic parts. Parts used
in the repair of AEM electronic components will be extra. AEM will provide an estimate of repairs
and receive written or electronic authorization before repairs are made to the product.
Page 6 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Part 1 – EMS-4 Installation
CPU Core:
16 bit / 40 MHz
Injector Drivers:
4 x Saturated (8 ohm minimum, High Impedance Only)
Coil Drivers:
4 x 0-5V Falling Edge Fire (do not connect directly to coil
primary)
GPIO Pins:
4 x 1.5A Low Side Output / 0-5V Analog Input / Switch Input
4 x 1.5A Low Side Output / 0-5V Analog Input / PWM output
O2 Sensor Input:
1 x 0-5V analog
Timing Sensor Inputs:
1 x VR (mag) Cam Input
1 x VR (mag) Crank Input
1 x Hall VSS Input
1 x Hall Crank Input
1 x Hall Cam Input
Knock Sensor Input
1x Programmable
Throttle Position Input
1 x 0-5V
Manifold Pressure Sensor
1 x 0-5V
Coolant Temperature Sensor
1 x analog
Inlet Air Temperature Sensor
1 x analog
USB
1 x EMS / PC Communication
CAN
1 x Programmable Send / Receive
Sensor Ground
1 x
5 Volt Reference
1 x
EMS-4 Basic Specifications
EMS-4 Specifications
Wire Harness Options
EMS-4 with 30-2905-96 Full Harness EMS-4 with 30-2905-0 Mini Harness
Page 7 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Page 8 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Page 9 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Two partially assembled harness options are available for the EMS-4:
1. P/N 30-2905-96 EMS-4 Full Harness
2. P/N 30-2905-0 EMS-4 Mini Harness
Photographs and schematics for each are shown above. The Full Harness option is best suited
to applications where no factory harness exists or where modifications are so extensive, it is
easier to build a custom harness. This harness includes a fused power distribution center with
main relay. All circuits are pre-terminated at the ECU connector. All sensor input and actuator
output leads are grouped and clearly labeled. All power and ground splices are pre-configured.
All sensitive communications and CAN data stream circuits are pre-configured.
The Mini Harness option is best suited to applications where the factory harness is suitable as a
starting point for modifications. Like the fully populated harness, the mini version includes preterminated CAN data stream and communications circuits. It also includes primary power and
ground inputs. This is the minimum required for powering up the EMS and enabling
communications. All other harness terminations are the responsibility of the installer. A bag of
Delphi/Packard female terminals is included for terminating all circuits at the main ECU
connector.
Installers choosing the Mini Harness option should refer to the Full Harness schematic
above and the EMS-4 System Diagram that shows an example of a complete system
design.
ECU Terminations with Mini Harness, P/N 30-2905-0
To following steps illustrate how to open the ECU connector backshell so additional circuits can
be added.
Begin by cutting the strain relief tie
wrap holding the terminal bag as
shown.
Page 10 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Using a sharp pick or
probe, push in on the
locking tabs holding the
outer retainer.
Remove the retainer.
Page 11 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Use pick to pry open the
retaining tabs holding the
backshell halves together.
Open the shell to expose
the cavities.
Page 12 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
To remove a terminal,
carefully pry up on the
retaining clip. Be careful
as the clips can break if
bent too far.
To add a new circuit,
insert the terminal from
the back as shown until it
clicks into place.
Page 13 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Showing terminal fully
seated.
Following is the proper tool for use with the Delphi Micro Pack terminals used in the ECU main
connector.
Delphi Part No: 12070948
Application: Unsealed Micro-Pack 100, Female only
Core and Insulation
Cable Range (mm2): 2.0-0.35
Page 14 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
The tool is available in many places. One is shown below. Web address –
http://www.mouser.com AEM recommends using the proper tool for all ECU terminations.
Image shows a properly crimped
terminal. Top View.
Page 15 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Side View. After crimping, be sure
to do a pull test to make sure the
terminal is properly installed.
Electronic Wiring Conventions
A proper wiring job includes proper termination of the wire at the sensor. The wire terminal end
must be moisture tight where it plugs into the sensor and it must have strong, electrically sound
terminals. The preferred method of securing a wire to a terminal is to use a crimp terminal with
NO solder. It is important to use the proper crimping tool for sound terminal construction.
Plastic terminal plugs must have moisture tight seals. Inspect each plug to make sure the seals
are in place. Also, before the plug is installed on the sensor, apply a dab of di-electric grease in
the terminal slots to further aid in corrosion resistance.
If a splice into a wire must be made and no solder-less terminals are available, then you must
properly solder the splice.
Noise can be a serious problem and can cause intermittent misfiring of the engine. Every
precaution should be taken to prevent interference to the ECU‟s operation. Resistive plug leads
are REQUIRED, and shielded cables from the crank and cam angle sensor inputs are highly
recommended. All racing AEM EMS wire harnesses come with properly shielded cables and are
color coded for easy identification of circuits. They are also shrink wrapped for abrasion
protection. The crank and cam angle sensor wire has a bare wire running down the length of it.
It is NOT terminated at the sensor end of the cable because we ground it at the plug end of the
harness. DO NOT GROUND THIS WIRE! This will cause a condition called ground looping
and will remove any noise protection the cable has.
To eliminate or reduce the chance of EMI, wires that carry high current must run in twisted pairs.
An example of this would be the power leads from a multiple spark ignition system. These
ignition systems can carry up to 100 amps for a couple milliseconds at the time of discharge,
which induces a strong magnetic field in close proximity of the wires.
Page 16 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
The routing of the wire loom is critical to EFI system performance and safety. The following
safety considerations should be made when installing the wire loom:
Heat protection: the loom should be placed away from or insulated from sources of heat.
The obvious item(s) that should be avoided are the exhaust manifolds, EGR delivery
tubes, and turbochargers. If it is absolutely necessary to route a wire in close proximity
to any of these items, then a suitable insulator must be used.
Noise suppression: do not route wires near the HT leads. For coil- on-plug ignition
systems this is not as critical.
Moving component protection: route wires away from moving components such as fans,
the blower belt, or the throttle linkage. Also, make sure the wires are not under any
strain when the engine is at full deflection on the motor mounts (we have seen map
sensor wires disconnect while under full acceleration because the motor mounts were
bad).
Never have the wires in exposed bundles throughout the engine compartment. A
professional harness has shrink tube over it to resist abrasion and chemical damage to
the wire loom.
Grounding
The ECU must have an electrically secure ground connection, which means that the battery
negative must be properly grounded to the chassis AND engine. The ground wire, whether it is
from the battery or to the chassis and engine, must have perfect electrical conductivity. This
means that there must not be any paint or rust under the wire terminal. Make sure that when
you install the ground wire there is bare metal exposed where the wire contacts the vehicle
component. To prevent rust build up, we recommend applying a protective layer of dielectric
grease, such as Standard Ignition SL-4, to the bare metal surface. The ground wire must be at
least the same gauge as the power lead to the ECU. We also recommend that the ground wire
be as short as possible.
Power Requirements of the AEM EMS
The AEM EMS requires a minimum supply voltage of 10V or greater to run. We recommend
that the ECU be supplied with 13.8V nominal operating voltage. Ensure that the vehicle‟s
charging system is in perfect operating condition prior to installing the AEM EMS.
Use of Relays to Control Ancillary Devices
Relays are remote switching devices that are used to isolate a device from the ECU‟s circuitry to
reduce noise and power constraints on the ECU. Typical devices that are powered by a relay
are:
Fuel Pump
Variable Valve Control
Oxygen Sensor Heater
ECU power
Nitrous Oxide solenoids
Page 17 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Noise can be caused by the electric motor in a fuel pump, which if connected directly to the
ECU, may feed back into the circuit board ground plane. In the case of a fuel pump, the typical
amperage required to run the pump is 10A or more depending on its size. The driver in the
ECU that sends the command to run the fuel pump is only capable of supplying 1.5A, and
clearly this type of load on the driver would cause it to burn out. There are drivers that can
handle larger currents but cost, size, heat dissipation, and noise problems prevent their use.
Typical relays in use today are capable of carrying 40A. A relay has an electromagnet
inside it that is used as a switch. This electromagnet, or switch, is used to position a
contact within the relay that is capable of carrying high current. There are typically four
or five terminals on the base of a relay. These terminals can be wired in several ways to
achieve different results. Refer to the EMS-4 System Schematic for common wiring
schemes used with relays.
Installation with Full Harness, P/N 30-3905-96
For the following section, please refer to the EMS-4 System Diagram for more
information. It shows a schematic representation of a properly designed system using
the fully populated harness.
NOTE: The columns in the connection tables below labeled “WIRE” refer to the wire
gauge recommended for the harness.
USB Connector
USB Connector
Page 18 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
A high quality over-molded termination is included for USB communications. Plug one end of a
standard USB extension cable (included) into the harness connector and the other end into an
open USB port on the PC. Communications is possible only when the EMS is powered up.
CAN Connector
CAN Connector
A compact pre-terminated connector is included for use with AEM CAN enabled devices.
Injectors
Injector Basics
A fuel injector is a valve that can be opened and closed very quickly. To open the valve, current
must flow through a solenoid contained in the upper part of the injector assembly. The EMS-4
triggers the injector by providing a ground path to the negative terminal. Fused power is
provided to the other terminal from the harness.
WARNING! – The EMS-4 is compatible with high impedance injectors only. For direct
drive operation, injector coil resistance must be greater than 8 ohms. Low impedance
injectors can be used if a suitable ballast resistor box or Peak and Hold Driver module is
used such as AEM P/N 30-2710.
To determine the size of the injectors, the total engine power must be estimated or known. The
fuel pump calculations and BSFC information mentioned in the Fuel Pump Sizing section on
page 135 provides a good understanding of the fuel requirements for an engine. The following
equation will allow you to determine the requirements of your injectors:
Page 19 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
((Power x BSFC) x (1 + Safety Margin))/Number of Injectors = pounds/hour
Name
Wire
Wire
Color
Stamping
Injector #1
22
Orange
INJ 1
Injector #2
22
Orange
INJ 2
Injector #3
22
Orange
INJ 3
Injector #4
22
Orange
INJ 4
Fused Injector Power
14
Red
INJ POWER
An example of this equation is:
6 CYL. engine rated at 500 hp on gasoline using moderate boost with a 15% safety margin on
the injector
500 x .625 = 313 lbs/6 = 52 lbs/hr/ injector. 52 x 1.15=60lbs/hr/ injector
If we take the flow of the injector (60 lbs/hr) and multiply it by the number of cylinders (6), we
arrive at a total of 360 lbs/hr of flow. As you can see, the fuel pump described in the fuel pump
sizing section referenced above has enough capacity to feed the engine with a little room to
spare.
It is a good idea to know the maximum operating pressure of the fuel injectors. In some cases
the fuel injector will not open if the fuel pressure exceeds the design limit of the injector. Also, at
the higher pressures the injector fuel flow may become non-linear and cause inconsistent fuel
delivery, usually creating a lean condition. Most injectors can withstand up to 70 psi. Many of
the pintle style injectors can withstand higher pressure.
In the fuel injector sizing, always use a safety margin between 15-20%.
Harness Connections
Injector Harness Connections
INJ1 – Connect to 1st injector to fire.
INJ2 – Connect to 2nd injector to fire.
INJ3 – Connect to 3rd injector to fire.
INJ4 – Connect to 4th injector to fire.
INJ POWER – Fused injector power. Splice required number of power leads and distribute to
each injector.
Page 20 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
AEM kit P/N 30-2020 (Optional) Bosch Style Injector Connector Kit contains the parts to
assemble 4 injector connectors. The kit contains Four Bosch style female injector connectors
and 10 contacts (2 extra contacts are included for spares).
IMPORTANT!
The contacts are “Pull to Seat” meaning you must feed the wire through the connector housing
BEFORE you crimp on the contacts. The wire is then pulled back into the housing and the
contact locks in place. The contact cannot be inserted or removed from the rear (wire side entry)
of the housing.
Contacts (10 Included)
Plating Tin Plated
Cable Range 1.00 - 0.05 mm2
Outside Cable Diameter 2.40 - 2.03 mm2
Temperature Range -40 to 125 C
Resistance in mOhms at 20 mV > 10.0 Ohms
Voltage Drop in mV per amp > 3.0 Ohms
Housing (4 Included)
Color Black
Cavities or Contacts 2
Gender Female
Temperature Range -40 to 125 C
Resistance at 20 mV > 10.0 mOhm
Voltage Drop per amp > 3.0 mV
Exterior Dimensions 27.8L X 29.6W X 20H
Seating Process Pull To Seat
Coils / Electronic Ignition System Basics
An ignition coil is charged when current flows through the primary side of the coil. A coil driver
is required to sink the current and dissipate the heat generated during operation. The coil
outputs from the EMS-4 are used to trigger the drivers. The drivers can either be contained
within the coils themselves or they can be contained within a stand-alone device installed
between the EMS-4 and the coils.
There are several different types of ignition systems in use on modern cars.
They are:
Distributed spark using a single coil and a distributor for all cylinders.
Wasted spark using one coil for two cylinders.
Direct Fire using one coil on plug of each cylinder.
Distributed Spark
Distributed spark systems have been around the longest. As the name implies, the spark is
distributed to the plugs via a coil output to a rotor, then through the distributor cap to the
appropriate plug via a high-tension (HT) lead. This is the most complex system because of the
relationship that has to be maintained between the firing point, rotor to cap terminal angle, and
Page 21 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
engine position. Distributed spark systems also rely on a mechanical link between the engine
Name
Wire
Wire
Color
Stamping
Coil 1 Output
22
Dk Blue
IGN 1
Coil 2 Output
22
Dk Blue
IGN 2
and ignition output, which adds another dimension of unreliability-and to a minor extentinaccuracy in timing. In addition to these problems, distributed spark systems typically produce
the least intense spark of all ignition systems. The time to achieve full charge diminishes as
engine speed increases; therefore the coil charge is reduced as a function of RPM. In spite of
the potential problems with distributed spark systems, they have been used successfully for
many years on high-performance engines. Distributed spark ignition systems respond well to
spark amplification within their design limits.
Wasted Spark
Wasted spark systems employ one coil for two cylinders. The term “wasted spark” comes from
the fact that each plug fires every engine revolution. On a 4-cycle engine, the piston is at Top
Dead Center (TDC) two times for every cycle; once for firing and again during the overlap
phase. The wasted spark coil fires one plug Before Top Dead center (BTDC) and another plug
just before the overlap phase (at the latest part of the exhaust stroke before the exhaust valve
closes). Wasted spark systems have a higher potential for spark intensity because the duty of
charging and discharging is split between the coils, which allows for more charge time per coil.
Additionally, wasted spark systems build up less heat in the coil, making it more reliable.
Wasted spark systems have been in use since the mid 80‟s on GM cars and on motorcycles for
considerably longer than that. There are no moving parts, no complicated relationships with a
cap and rotor to maintain, and they deliver very accurate spark timing. Furthermore, multichannel spark amplification systems to enhance spark duration or intensity are available for
wasted spark ignition systems.
Direct Fire
Direct fire systems employ one coil on each spark plug and is the most reliable system used
today, (this type of system is used on most modern cars). Each coil fires sequentially in the
cylinder firing order. The charge time for each coil is twice as long as those of a wasted spark
system, which allows direct-fire, coil manufacturers to build compact, lightweight coils that retain
sufficient spark energy. There are no moving parts to wear out and no HT leads that will
deteriorate. The lack of HT leads in direct fire systems is a major advantage for an EFIequipped car because there is a very low incidence of noise due to leaking or improperly routed
wires. There have been incidences of the terminal from a direct-fire coil (that attaches to the
spark plug) cracking and subsequently causing Radio Frequency Interference (RFI) or “noise” to
the ECU. This will cause engine operation problems, but it should be noted that these cases
are extremely rare.
Harness Connections
Coil Harness Connections
Page 22 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Coil 3 Output
22
Dk Blue
IGN 3
Coil 4 Output
22
Dk Blue
IGN 4
Fused Coil Power
14
Red
COIL PWR
Coil Ground
14
Black
PWR GND
Warning! - The ignition outputs from the EMS-4 are not designed to trigger an ignition
coil directly. Connecting them to a coil that does not contain a built-in driver will damage
the EMS-4. Coils without built-in drivers typically have only two pins on the connector.
Coils with built-in drivers typically have 4 or more pins on the connector. If you are not
sure what kind of ignition coils you have, contact AEM tech support for help.
IGN 1 – Connect to 1st coil driver to fire.
IGN 2 – Connect to 2nd coil driver to fire.
IGN 3 – Connect to 3rd coil driver to fire.
IGN 4 – Connect to 4th coil driver to fire.
COIL PWR – Fused coil power. Splice required number of power leads and distribute to each
coil.
PWR GND – Ignition power ground.
AEM Kit P/N 30-2840 (Optional) Four Channel Coil Driver is custom manufactured to AEM‟s
specifications by HÜCO Electronic GmbH in their ISO 9001 facility in Germany. It has been
specially designed by AEM for driving the high power dwell controlled ignition coils commonly
found on performance engines.
The 30-2840 Kit contains:
Four Channel Coil Driver
Five Pin Mating Connector
Four Pin Mating Connector
10 Terminals & Wire seals (one extra of each as a precaution)
Mounting hardware
Thermal Grease
Page 23 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Coil Driver
Connect to
ECU Coil 1 Output
EMS-4 harness, IGN 1
ECU Coil 2 Output
EMS-4 harness, IGN 2
ECU Coil 3 Output
EMS-4 harness, IGN 3
ECU Coil 4 Output
EMS-4 harness, IGN 4
Ground
EMS-4 harness, PWR GND
Coil 1 Negative Terminal
Coil 1 Negative Terminal
Coil 2 Negative Terminal
Coil 2 Negative Terminal
Coil 3 Negative Terminal
Coil 3 Negative Terminal
Coil 4 Negative Terminal
Coil 4 Negative Terminal
AEM Four Channel Coil Driver P/N 30-2840
Four Channel Coil Driver Connections
Coil Driver Connections
CDI Installations
The ignition outputs from the EMS-4 are considered a falling edge fire signal where signal high
is dwell time. A coil driver will invert the signal from the EMS-4 pulling the signal low (ground)
and allowing current to flow through the coil primary windings. Some CDI ignition boxes are
only capable of triggering on the “rising edge” or “Points Trigger” signal. These systems will still
require an in-line coil driver to invert the ignition output to fire on the correct edge. The AEM
Twin Fire CDI system P/N 2820 (8 channel) and 2821 (4 channel) can be configured to fire on
either a rising or falling edge. Applications using an AEM Twin Fire will not require an in-line coil
driver. Contact your CDI manufacturer for more information.
Page 24 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Signal comparison – before and after coil driver
DWELL
DWELL
FALLING
5V
GND
IGNITION OUTPUT FROM EMS TO COIL DRIVER OR CDI
IGNITION OUTPUT AFTER COIL DRIVER
DWELL
DWELL
RISING EDGE
12V
GND
EDGE FIRE
FIRE
Page 25 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Name
Wire
Wire
Color
Stamping
+5.0 volts, Vcc
22
Red
VCC
Throttle Position Sensor
22
White
THROTTLE
Sensor Ground
22
Black
SIG GND
Name
Wire
Wire
Color
Stamping
+5.0 volts, Vcc
22
Red
VCC
Manifold Pressure
Sensor
22
White
MAP
Sensor Ground
22
Black
SIG GND
TPS (Throttle Position Sensor)
Harness Connections
TPS Harness Connections
VCC – Connect to sensor 5 volt reference
THROTTLE – Connect to sensor signal
SIG GND – Connect to sensor ground
MAP Sensor
Harness Connections
MAP sensor harness connections
VCC – Connect to sensor 5 volt reference
MAP – Connect to sensor signal
SIG GND – Connect to sensor ground
Optional AEM MAP Sensor Listing:
AEM P/N 30-2130-30 “MAP Sensor Kit, 2 BAR”
Typically used to measure intake, air box and crankcase pressures.
AEM P/N 30-2130-50 “MAP Sensor Kit, 3.5 BAR”
Typically used to measure intake & exhaust back pressures.
Page 26 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
AEM P/N 30-2130-75 “MAP Sensor Kit, 5 BAR”
Name
Wire
Wire
Color
Stamping
Inlet Air Temp Sensor
22
White
AIR TEMP
Sensor Ground
22
Black
SIG GND
Typically used to measure intake & exhaust back pressures.
Air Temp Sensor
Harness Connections
Air Temperature Sensor Harness Connections
AIR TEMP – Connect to sensor signal
SIG GND – Connect to sensor ground
AEM P/N 30-2010 (Optional) Air Temp Sensor kit is specifically designed for temperature
measurements in automotive systems. The kit contains One GM style temperature sensor, one
“6” Flying Lead” mating connector assembly and a weld in aluminum bung.
Air Temperature Sensor Diagram
Housing Material: Brass with 3/8” NPT Thread (Torque to 25 Ft-Lbs)
Elec. Termination: Integral weatherproof connector, Includes mating connector with 6” leads,
18 AWG.
Wiring to your EMS: Polarity does not matter. Connect one wire to harness AIR TEMP lead
and the other to harness SIG GND lead.
Page 27 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Name
Wire
Wire
Color
Stamping
Coolant Temp Sensor
22
White
COOLANT
Sensor Ground
22
Black
SIG GND
Water Temp Sensor
Harness Connections
Water Temperature Sensor Harness Connections
COOLANT – Connect to sensor signal
SIG GND – Connect to sensor ground
AEM P/N 30-2011 (Optional) Water Temp Sensor kit is specifically designed for temperature
measurements in automotive systems. The kit contains One GM style temperature sensor, one
“6” Flying Lead” mating connector assembly and a weld in aluminum bung.
Water Temperature Sensor Diagram
Housing Material: Brass with 3/8” NPT Thread (Torque to 25 Ft-Lbs)
Elec. Termination: Integral weatherproof connector, Includes mating connector with 6” leads,
18 AWG.
Wiring to your EMS: Polarity does not matter. Connect one wire to harness COOLANT lead
and the other to harness SIG GND lead.
Page 28 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Crank Sensor
Crank Sensor Basics
The crank sensor is used to calculate engine speed, ignition timing and injection phasing
angles. It senses a toothed wheel (reluctor wheel, reluctor ring, etc.) and converts this pattern
into a voltage/frequency signal that the EMS uses for basic calculations. Either on its own, or
combined with the cam position sensor, it is the most important input to the system. There are
two basic types of crank sensors, variable reluctance (VR or “mag”) and hall-effect.
VR Sensor raw voltage signal
Page 29 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Hall Effect voltage signal
The internal circuitry on the EMS is different depending on what type of sensor is being used.
Note that there are two different inputs on the EMS for crank and cam position. One for a Hall
Effect type pickup. The other for a VR or “mag” pickup.
The EMS-4 crank sensor VR inputs go through a signal conditioning chip on the circuit board
that converts the raw (zero crossing) signal into a clean 0-5V square wave signal as shown
below. The signal conditioning circuit will invert the significant edges of the raw signal. The
consistent edge of the raw signal in the example below is the rising edge. The conditioning
circuit inverts the signal and creates a falling significant edge.
Page 30 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
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