TECHNICAL NOTES ON THE EEC-IV MCU - Auto diagnostics

Technical Notes on The EEC-IV MCU
EEC EFI MODIFICATIONS & UPGRADES
Compiled by Tom Cloud
(font is Courier New)
SD TO MAF CONVERSION
Information on MAF conversion sent to me by Bob Nell bnell@utk.edu
(This is specifically for ’87-’88 SD 5.0 Mustangs.)
Eectch98-Part5.fm
I started with a stock ’88 Speed Density 5.0 LX and got the MAF sensor, bracket,
tubing, EEC-IV and manual tranny from a wrecked ’91 LX MAF 5.0. (The Cobra MAF is
different than the GT/LX MAF in that,in the Cobra, both the EEC and the MAF have
been recalibrated for 24# rather than 19# injectors. So, if using Cobra components,
use a Cobra EEC.) The MAF connector was purchased from a dealer for about $10 and
came with solder, shrink wrap and splicing instructions. If a complete harness is
required, there are companies that sell used ones.
You will need:
• Mass Air Flow meter calibrated for the injector size (using mismatched parts
can cause part throttle detonation and drivability problems).
• MAF bracket and mounting screws (3).
• MAF 4-wire connector, wiring to go to the EEC connector and EEC connector pins
for two of the wires.
• MAF ductwork -- the tubing that goes from the engine to the MAF, from the MAF
to the air cleaner and then to the intake scoop. Some clamps will also be
needed to hold it in place.
• Extra EEC connector pins for hooking up the VSS and FPM2 signals.
The first step will be to remove the old speed density computer from behind the kick
panel on the passenger side. Remove the kick panel, the retaining screw on the lower
right of the ECM, push the wires out of the way and then, using a 10 mm wrench,
remove the ECM.
There are unused female pins (sockets) in the harness end of the EEC connector.
Seven of these will be needed to add the necessary inputs (it can be done with four,
but it’s not recommended). Looking at the connector, there is a red "H" piece of
plastic that needs to be popped out of the connector to allow the pins to be
inserted/removed. It can be pushed out from behind (the wire side) then a small
pick will be needed to allow the pins to be removed.
To be added:
• 4 Inputs for the MAF.
• 2 Inputs from the VSS (if you don’t already have cruise control, you will have to
add a new speedometer cable with VSS and appropriate wiring).
• 1 Input from the Fuel Pump Relay.
If cruise control is present, run the 2 VSS inputs to the speed control amplifier
instead of routing wires outside the car to the tranny. The amplifier is the yellowish
plastic box located near the driver’s left foot. There are also a couple of
pinout changes between the speed density and the MAF EEC that require swapping a
couple of pin positions - if it’s as remembered, they are the TAB/TAD (thermactor
air bypass/diverter) pins.
Attach these 4 wires from the MAF to the EEC
EEC-IV Technical Notes: Modifications/Upgrades56 last edited: 9/29/98