I'm trying to get a TPI running good to put in my car. This TPI system was assembled it would seem. BEFORE I got it. So I get the golden oppurtunity to straighten it out.

-MAIN QUESTION - Does the 1989 ECM support IAC? Wiring harness appears factory with the IAC.

-The ECM is for 1989 350 - as long as it hasn't been modified. APYN 3496 3481 Auto 2.77 Fed F

-The Plenum is a 1990. Has a MAP sensor hole and short fins, so supposedly doesn't have the IAC hole in it. I can machine it if necessary.

-Has MAF with the Idle Air Control (MAP was removed)

-Car is a 1990 IROC 350

-Here's the problem - Will the ECM control the IAC? It is plugged in, but I thought the ECM for 89 didn't have IAC? (from 'TPI swappers GUide' book, page 20)

-Since it is plugged in, could the wiring harness be for an 85 to 88? And the ecm just doesn't know it exists because it is for 1989? I'll be checking signals to and fro today.

BTW - not throwing codes now, changed TPS and set voltage to .59 at idle. Car will not start on its on, have to press throttle or spray some ether. Once it is running it stays running but idle bad and I had to crank the idle screw up to get this.

What do you think?

Thanks a lot.

 

First of all, I think that from '85 thru 2002, all F-body EFI cars had an IAC. Think about it, the IAC is the only way an ECM controls the idle speed. Also, as far as I know, the IAC is always mounted to the side of the TB (throotle body). It seems from you wrote above, the IAC is mounted to the plenum. That is not true.

 

yeah the IAC is actually inside the throttle body. Your Intake Air Temp. is mounted underneath your plenum. And just curious why did you swap a speed densinty setup(no MAF) to a MAF setup?? The Mass Air Flow sensor stopped in 1989, 1990-1992 cars had no MAF.

 

Sounds like you have a MAF computer hooked to a MAP electrical system. Not sure if any inputs use the same ports in each computer.
Probably any computer from 90 to 92 5.7 computer should work, with 90 to 92 prom.

 

Yep, there is a pin difference between the '89 MAF ECMs and the '90 MAP ECMs. If you still you using the '90 wiring harness, its best to stay with the '90 ECM and use the MAP sensor setup, and get rid of the MAF sensor. Most guys go from MAF to MAP, and they have to repin the harness connections at the ECM.

 

The car was like this when I got it. But set up for over a year. I bought it for the motor. It runs and doesn't smoke, but the idle is rough and will only start if I press on the accelerater. So, I'm checking IAC and adjusting, Injectors, EGR, valve adjustment, changed and adjusted TPS, injector wiring, and timing. When it is perfect, I'll begin the swap. I have vacation first week of April and want to be ready. Swapping rear, trans (man to auto) engine, wiring harness, parts of suspension, fuel lines, fuel pump. Have to change oil pump gaskets and crank bearings. A lot to get done in a week for one person. 25 years rebuilding cars from ground up - first real in-depth fuel injection work.

The 'TPI swappers GUide' book is misleading if all the TPIs have IAC. Read page 20 and see what you think. Real experience is better - the reason I came here.

1990 car
1989 ECM and it looks like wiring harness also (if I had 1990 I would gladly go to MAP.)
I took the throttle body off and the plenum does have a factory cutout for the IAC to work. So that won't be a problem. Book said different.

Pulling the injectors tomorrow to see if they are spraying. They all ohm correctly.

How do I tell if the wires are on the correct injector? I'll do a search, but if it is like all my other searches, I'll answer every other question I have but the one I'm searching for.

Thanks for the help.

 

It does not matter which injector plug goes to which injector, they can be all switched because the ECM is batch fire,, all injectors fire at the same time, once per crank rotation.

 

Thanks for the reply. found two that are not spraying. they do click when voltage is put to it. Trying to clean them gently before I send them out.