I have an 87 Formula, has TPI, (obviously since I would not be posting here) I just took the intake apart, and put some new runners and Plenum on it. Put it back together and the car will NOT idle.... I am thinking the IAC, but not for sure, I have checked all my connections I could touch and see, but it will not run.

I disconnected the brake booster to let some air in and it would somewhat idle, but I do not want to keep it like that

Any ideas...

John

 

Could you be a bit more specific on how idles? I gather it idles badly, but is it just low? Does it jump around? Need a tad bit more.

 

Might take the IAC out and start it for a few seconds. Should run about 3000 rpm with the port wide open. Maybe you have a gasket in wrong shutting off the idle circuit?

 

The car will not idle on its own, I start it and its like I turn it immediately off...

If I feather the trottle I can keep it running and it runs. take foot off throttle and it dies again...

I had a long hard sleep over it and I am going to start with the TPS and MAF, then go to the IAC...

I do not think it would be a gasket as I was careful to put it together right. THe only gaskets I messed with were the throttlebody to Plenum, plenum to runners, and runners to intake base...

John

 

Thanks for all your thought, I figured it out...

Here is what went wrong...

As we know from 85-88 the TPI cars had the cold start injector (9th injector). To operate this the IAC air would run through the bottom of the plenum, down a small pipe on the drivers side runner, and then would meet up with the Cold Start Injector. From there the cold start injector would feed into the runners.

Starting in 1989 GM dropped the cold start injector, and illiminated the extra pathway down into the intake base. Since the old pathway had a dual purpose (supply the IAC air, and the cold start injector) they cut out a 5/16" deep, 1/2" tall notch on the back of the throttlebody between the butterflies for the IAC to work.

What happened is I got a set of runners that did not have the small pipes running from the plenum down into the base. So when I would try to start the car it would die because there was no functioning IAC... To correct this I took a milling machine and milled a similar slot as the 1989+ from the IAC port to the the large holes where butterflies are in the throttlebody.

Since I no longer use the Cold start injector I had no problems after that...



John