Hello 3rd gens, so got a leak in the rail o rings was running good prior.
replaced o rings put tpi back together and started car . Ran choppy but started right up. Took a look and realized I left off under plenum vac lines and middle lower bolts from top runners to plenum. I fix everything and it won't start and run. Reset iac. Still won't run. Pull out two middle lower bolts to create vac leak ,runs like sht but runs. Put bolts back in , won't run. I double checked everything today and smoke tested. No leaks, My only thoughts are air issue, iac? Going to take throttle body off again Tommorow but figured it's worth posting ,probably only post where a vaccuum leak let's car run. Any thoughts?

 

Runs better with a vacuum leak means it's running rich. Too much fuel or not enough air.

 

yeah I was thinking not enough air but I just finished taking off iac and it's working fine. So I'm guessing it's not air,

 

With an IAC reset you will most likely have to crack the throttle on start up as the pintle is fully seated. After a few minutes with IAC relearn it should adjust back to a position to allow it to enter into idle mode. Perhaps you already did this but figured it was worth mentioning.

 

There are two throttle body to plenum gaskets. One for 1988 and earlier TPI systems and one for 1989 later TPI systems. I've always wondered what would happen if you used the wrong style gasket on the other style throttle body & upper plenum. I know you can use one style throttle body on the other style plenum and it's OK I hear, but the other way around and it isn't OK and you have to machine a hole into the face of the plenum for it to work.

Most the gasket kits today have only one style of the TB to plenum gasket in them.

This very well isn't your problem though. Most people use the kit without the lower intake manifold gaskets with just the one style TB gasket when working on their TPI system and I've not heard any complaints about it.



Gasket kit for a 1985 to 1992 F-Body. The two different style TB gaskets are in the middle upper right. Lesser gaskets kits without the lower intake manifold gaskets only have the gasket that's in the middle of the picture. You can buy either of the two styles TB gaskets by themselves.


Only has one style TB gasket. So if might not matter at all. IDK

 

thanks, yeah I'm stumped on this, was running good when I put it away for winter, just a leaking rail. Now that rail fixed i can't understand it staying running with a bigger vacuum leak. Going to watch the iac steps Tommorow on laptop. Thanks

 

I use the triangle 🔺️ actually didn't know there were others as the triangle matches the throttle body opening

 

So I just unplugged the maf to see if that was my issue. Didn't get a SEL, should that of come on immediately ? If I recall correctly it immediately illuminates.

 

Depends. There's two scenarios. If its unplugged with the ignition switch off and upon startup it should send the fault immediately. The second one is a little tricky. States RPM above 600 but not sure if thats the only criteria or if its above 600 rpm with the TPS above 6%.

Would like to know as I run TBI

 

Thanks that's Interesting, also say in netural which is odd. I can barely get it to run now but did give it a rev when it did. Now that makes me think I may have a ECM issue. Hmmmm

 

This is worth reviewing too.

 

Yes, and that diagram makes me think it would set with sel, with key on not running as it administers a pre test. Thanks.