New to the EFI world!

If you are spitting a KOER EGR code, the computer turns off the EGR function. You can play with resistors to get rid of the CEL from there.

Good luck.

blue66tang said:

Oops i just re-read my post. I dont care if it works OR NOT jsut as long as it doesnt throw a code or make the engine run rough. So how can I run test codes on it. I am reading on fordfuelinjection.com that there needs to be a self test input. I know my harnes does not have this because I have been over my harness like a mad man. So how can i ad this connector and where does it go?

Click to expand...

Congrats on the upgrade to efi.
You will soon either be bald from pulling out your hair...
OR
you will be wondering what you were thinking for all those years with a carb.



You will have to use a wiring diagram to find where the EEC Test harness should be spliced back in. Check Autozone for some decent diagrams. Double check ALL of the wire codes on your harness to what is called out in the diagram, as Ford liked to change the wire harnesses out of year.
My 90GT has a 91GT harness.

The best book out there for learning Ford EEC-IV efi is...
Ford Fuel Injection & Electronic Engine Control How to Understand, Service and Modify by Probst
This book will clarify what the computer is doing, and goes into a little about how and why as well.
A very good read

Per the Ford documentation on alternate strategies, the computer shuts off all fuel and timing compensation that would be used when the EGR is non functional.
In other words, if the computer thinks something is wrong with the egr, it stops making adjustments to the fuel and timing.


:SNSign:

Here's some generalized help for you. while it is not specific to
your exact problem, it has the basics you need.

Fix the can't dump the codes problem and your other problems may go
away as a result. The can't dump the codes problem is usually a wiring
problem that affects the signal ground for the MAP/BARO, ECT, ACT,
TPS & EGR sensors. The same wire that acts as signal ground is the
return path for the test mode circuit.

When the computer won't go into diagnostic mode, there are usually
several other problems hiding that reduce performance considerably.

With the power off, measure the resistance between the computer
test ground (black/white wire) on the self test connector and battery
ground. You should see less than 1.5 ohms.


A photo of the connector as it is wired in the car..



Diagram courtesy of Tmoss & Stang&2birds



If that fails, remove the passenger side kick panel and
disconnect the computer connector. There is a 10 MM bolt that holds
it in place. Measure the resistance between the STI computer self
test connector (red/white wire) and pin 48 on the computer main
connector. You should see less than 1.5 ohms. More than that means a
break in the wiring .

Measure the resistance between the black/white wire on the computer test connector
and pin 46 on the computer wiring connector. You should see less than 1.5 ohms.
More than that means a break in the wiring .


Next measure the resistance between pin 46 on the computer and pins 40 & 60.
They should be less than 1.5 ohms. If it is more than 1.5 ohms, then the signal
ground inside the computer has failed. Unless you are an experienced electronic
repair technician, this means the computer needs to be replaced..

More Tmoss Diagrams...



See the following website for some help from Tmoss (diagram designer) & Stang&2Birds
(website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine

The following is a view from the computer side of the computer connector.