INSTRUCTION
MANUAL
FOR
CHEVROLET
APPLICATIONS
(including LT-1)
www.accel-ignition.com
ACCEL/DFIACCEL/DFI
Installation Manual For The ACCEL
Digital Fuel Injection Engine
Management System
Prior to starting the installation of your ACCEL/DFI system,
read this manual carefully!!
Contents Page
Number
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
I) Obtaining Your Manifold . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
II) Setting Up Your Manifold . . . . . . . . . . . . . . . . . . . . . . . . . . 3
III) Mounting Your ACCEL ECM . . . . . . . . . . . . . . . . . . . . . . . . 3
IV) Injector Harness Installation . . . . . . . . . . . . . . . . . . . . . . . . 4
V) Main Wire Harness Routing and Connections . . . . . . . . . 4
VI) Choosing Your Distributor . . . . . . . . . . . . . . . . . . . . . . . . . . 5
VII) Fuel Pump Mounting and Fuel Line Installation . . . . . . . 6
VIII) Mounting The Oxygen Sensor . . . . . . . . . . . . . . . . . . . . . . . 8
IX) Air Cleaner Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
X) TPS Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
XI) Starting the Vehicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
XII) Optional Items . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
XIII) Trouble Shooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Some parts are not legal for sale or use in California
or on any pollution controlled motor vehicle.
INTRODUCTION:
CONGRATULATIONS! You have just purchased the finest
engine management system available. Fuel injection control
is an exact science that ACCEL has made simple. This manual
is written to assist you with the installation of your new
system. Please read the manual carefully.
Prior to starting your installation, please verify the contents
of your ACCEL/DFI package. You should find the following
components:
Electronic Controls Module (ECM)
Main Wire Harness (MWH)
Injector Wire Harness (IWH)
Manifold Absolute Pressure (MAP) sensor
Heated Oxygen Sensor with mounting nut
Coolant Temperature Sensor (CTS)
If you are missing any item,
please contact your dealer immediately.
Although the package you just received is designed to allow
you to convert a carbureted engine to fuel injection or allow
you better control over your present fuel injected engine, it
does not include the hydraulic portion of the installation.
If you need a fuel pump, filter, fittings, etc. Contact
your ACCEL EMIC center for the proper ACCEL/DFI part
numbers for your application.
1ii3
ACCEL/DFI
2
ACCEL/DFI
ACCEL/DFI has a number of fuel injection manifolds
for small block and big block Chevrolets available. With a
growing selection of manifolds, ACCEL/DFI should be able
to satisfy almost any engine combination. For the
combinations that would not be satisfied by our proven
manifold designs, including applications not covered,
ACCEL/DFI has the hardware necessary to modify a carbureted style intake for multi-port injection. Contact a dealer or
reference our catalog for part numbers. ACCEL/DFI also has
Engine Management Installation Centers (EMIC) that can not
only install and tune your system but many can also fabricate
or modify an intake for you as well. For the nearest EMIC to
you call: 1.800.992.2235.
Prior to installing your manifold make sure that gasket
surfaces are clean. ACCEL recommends using a 180 degree
thermostat. Place your thermostat and gasket onto your
manifold, put your thermostat housing onto the manifold
and bolt in place. If your are using TPI manifold, whether it
is stock or an ACCEL unit, you will have to place the injectors
into the fuel rail and bolt them onto your manifold before
you bolt the runners and install the injector harness. Be
careful when installing the fuel injectors so as not to cut the
O-rings. A small amount of oil on each O-ring will aid in the
assembly. If you are using a factory 1985-89 plenum you will
need to plug off the Cold Start Injector port, use ACCEL/DFI
part number 74820 to do this.
NOTE: It is recommended at this point to use a
hole saw (i.e.: Green Lee punches) to put two (2)
1-5/8” diameter holes in the firewall to
accommodate the main wire harness. Refer to
Figure D for hole locations.
Prior to bolting the throttle body to the plenum, we recommend cleaning the throttle blade, bore, IAC pintle and
seat area. Depending on the age and prior use of a used
throttle body, a significant amount of gum can accumulate in
these areas and affect the idle characteristics of the engine.
Plumbing Connections:
a) A vacuum line must be attached between the fuel
pressure regulator and the right rear side of the plenum.
Do not splice into this vacuum line; this can promote an
erratic vacuum signal.
b) Use a 7/16” diameter hose to connect the oil breather on
the valve cover to the right side of the throttle body, if so
equipped. If not plug the corresponding port off on the
throttle body.
c) Use a 5/32” diameter vacuum line from the bottom of
the throttle body to the vacuum advance canister on the
distributor. This is a ported vacuum signal. (This is only
used with non-computer controlled HEI ignitions).
d) On the left side of the base manifold (on factory TPI and
ACCEL base manifold) a barbed fitting is located. Use a
3/8” PCV hose to attach this to the PCV valve on the left
valve cover. If you will not be using this, plug the barbed
fitting.
e) Install a 3/8” diameter vacuum line from the rear
barbed fitting on the plenum to the brake booster unit.
f) Finally, use a vacuum line to connect the MAP sensor to
the right rear plenum fitting. Make sure not to splice into
the MAP sensor vacuum line, this could promote
inaccurate sensor readings.
II – SETTING UP YOUR MANIFOLD
I – OBTAINING YOUR MANIFOLD
ACCEL/DFIACCEL/DFI
An overview schematic of the main wiring harness
(MWH) is shown in Figure B (Page 23). The harness can be
routed and connected as follows: Begin by connecting the 32
pin and 24 pin ECM connectors to the ACCEL/DFI ECM,
making sure that the tabs snap into place. Then route the
longer of the two legs through the drivers side firewall hole
that you cut in step two, followed by the shorter of the two
legs though the passenger side firewall hole. Continue
pulling the harness legs through the firewall until the rubber
grommets seat themselves in the firewall. Once the
grommets have been properly seated into the firewall, each
leg of the harness can be routed between the manifold and
the valve covers.
The drivers side leg will contain connectors for the following:
• MAP (3-pin green male connector, refer to
Figure B for mounting location)
• Computer controlled HEI (4-pin male black
connector)
• ESC (1-pin female black connector)
• Air (2-pin Grey connector)
• Coolant (2-pin black connector)
• TPS (3-pin black male connector)
Connect each to the appropriate sensor using Figure B as a
reference. If this is a ACCEL system for an LT-1 engine
(74022-L), there will be an Opti-spark harness that will
connect the Computer controlled HEI connector, a TPS
extension harness, IAC motor adapter as well as adapter
harnesses for the air and coolant sensors. If you are missing
5
III – MOUNTING THE ACCEL ECM
4
The ECM comes with three (3) mounting tabs designed for a
#8 sheet metal screw. It is recommended to mount the ECM
in the passenger side kick panel. If the kick panel has an air
vent incorporated into it, DO NOT mount the ECM here.
This is not waterproof and therefore, needs to be mounted in
a location free of moisture. The alternate location is in the
dash board area behind the glove box. NEVER MOUNT THE
ECM IN THE ENGINE COMPARTMENT!
It is strongly recommended that this harness be installed
prior to mounting the plenum. Refer to Figure A for routing
the injector harness.
This ACCEL/DFI system is simultaneous double fire, therefore,
an injector connector may be connected to any injector, but
for your convenience, the connectors are paired in two’s,
similar to the way the injectors are mounted in the manifold.
Route the injector harness onto the manifold as shown in
Figure A (Page 22). After properly aligning the injector
harness onto the injectors, clip the connectors into place,
making sure that the metal clips snap into place. After the
main wiring harness has been installed, connect the injector
harness round 5-pin female connector to the MWH’s round
5-pin male connector.
IV – INJECTOR HARNESS INSTALLATION
V – MAIN WIRE HARNESS ROUTING
AND CONNECTIONS
ACCEL/DFIACCEL/DFI
any of these harnesses please contact your dealer immediately.
Make sure to connect the switched +12 volt wire (long pink
wire with a female spade connector) to a switched ignition
accessory in the fuse box. The switched ignition accessory
must maintain 12 volts during cranking, if it does not the
vehicle will not start.
NOTE: If you are not controlling timing with the
ACCEL/DFI ECM (using a non-computer
controlled HEI, points distributor, etc.) you
will not be using the computer controlled HEI
connector (4-pin male black connector) or the
ESC connector (1-pin female black connector).
The passenger side harness leg will contain the following
sensor connections:
• Oxygen (3-pin female black connector)
• Injector (5-pin round white connector)
• Tach pick-up (1-pin brown connector)
• Fuel pump (bare lead, red wire with
white stripe)
• IAC (4-pin square male black connector)
Connect each to the appropriate sensor using Figure B as a
reference. If you need to lengthen the fuel pump wire to
reach your fuel pump, make sure to use at least 14 gauge
wire. Finally, be sure to connect both the positive and ground
terminals of the MWH DIRECTLY to the battery. If you fail to
do this intermittent and unusual problems may occur.
NOTE: If you are controlling timing with the
ACCEL/DFI ECM (using a computer controlled
HEI, TFI, etc.) the Tach pick-up will not be
used. If you connect the Tach pick-up and the
Computer controlled HEI connector at the same
time, your ECM will cancel both of them out,
resulting in a no spark situation. In many cases
this will also damage your ECM.
At this time you can connect your User Interface Module
(UIM, or Power Tuner) to the MWH by connecting the 6-way
connector (located near the ECM connectors) to the 6-way
connector on the UIM. If you did not order a UIM there is
nothing for you to do with the 6-way connector on the main
harness. If using a UIM, mount the unit with two (2)
#8 sheet metal screws or pan head screws with nuts,
in a location convenient to the driver. See section XII for
description.
NON-COMPUTER CONTROLLED IGNITION
If you are using a non-computer controlled HEI (prior to
1985), points style distributor, etc. the Tach pick-up (1-pin
brown connector) must be used. Connect this lead to the
negative side of your coil. If the brown connector must be
removed for your application, be sure not
to remove the 39K
ohm resistor which is 3” from the existing connector.
NOTE: If you are using an aftermarket ignition
enhancer box (i.e.: ACCEL 300+, MALLORY
Hyfire) the MWH’s Tach pick-up connector
MUST be connected to the enhancer box’s Tach
output signal. It is also necessary to remove the
39K ohm resistor from the Tach pick-up wire. It is
3” from the end of the Tach pick-up lead. DO
NOT connect this lead to the negative side of
your coil if using an enhancer box, this can result
in ECM damage.
76
VI – CHOOSING YOUR DISTRIBUTOR
ACCEL/DFIACCEL/DFI
ACCEL strongly urges the use of a good quality suppression
wire such as ACCEL 300+ or ACCEL RFI Suppression Wires.
We have encountered problems with various ignition wires
available on the market such as helically wound or solid core
not suppressing electrical noise. The use of these wires may
interfere with the operation of the ECM. Further, some high
energy aftermarket ignition units also produce electrical
fields which will interfere with the ECM’s operation. Use of
these units is strictly at the risk of the owner. Call ACCEL for
recommendations of ignition system compatibility.
The total advance you set the engine to will depend upon the
engine you have. Vacuum advance should be controlled with
the EGR port, which is located on the bottom of the throttle
body. ACCEL/DFI recommends a distributor with
adjustable vacuum advance. Once the total advance is set,
connect the vacuum advance canister. Adjust the vacuum
advance canister to maintain 20-26 degrees with a hot engine
at 800 RPM. Again, this is ACCEL’s recommendation,
depending upon the compression ratio and cam profile, you
may have to decrease timing to avoid detonation.
COMPUTER CONTROLLED IGNITION
If you are using a GM (F or Y body) computer controlled HEI
distributor the MWH’s four pin male black connector must
be used. When using a Y body HEI , the four pin between the
HEI and the MWH is compatible. However, if you are using
a F body HEI, the four pin connection on the MWH will not
plug directly into the distributor. In order to use a F body
HEI you will need additional wiring. ACCEL/DFI’s part
number 74170 will allow you to connect your distributor to
the MWH. You can also control timing with the ECM by
using a magnetic pick-up distributor or crank trigger. In
order to control timing with these ignition systems you
must get a modification done to your ECM (ACCEL/DFI
part number 74043-I), this modification will come with the
necessary additional wiring, but will not come with an
ignition enhancer box that is required. If you will need this
modification contact ACCEL/DFI for further instructions
and a shipping address.
In order to set the initial timing, the ignition bypass
connectors (white-one pin connector), incorporated into the
HEI leg of the main wiring harness, must be disconnected.
With the engine running hot at 800 RPM, manually adjust the
distributor to 6 degrees BTDC. Once adjusted, reconnect the
ignition bypass line. As soon as you connect the bypass line
the timing will then be controlled by the ECM. The spark
curve is preprogrammed into the ECM from ACCEL/DFI. It
has as initial timing of 20 degrees BTDC and a total timing of
34 degrees BTDC in by 3000 RPM. The timing curves, as well
as all other tables in the ECM, can be adjusted to better suit
your engines requirements using ACCEL/DFI’s calibration
software CALMAP.
NOTE: If an aftermarket ignition enhancer box
is used (i.e.: ACCEL 300+, MALLORY Hyfire)
the Y body HEI can be wired as described by
the manufacturer. However, if you are using
an F body HEI or controlling timing with a
magnetic pick-up distributor or crank trigger
please reference figures E and F.
98