This is the second post for this topic. I have a '89 Formula 350 with a stock 350TPI. It idles rough when the engine is warm. i replaced the plugs, wires, and O2 sensor. I was told to clean to IAC motor but I can't fiqure out how it comes off the throttle body. There apprears to be no way of removing it without removing the TB. Any help here would be greatly appreciated. Any other thoughts on the rough/suging idle? It sometimes surges between 650-800 RPM.

Thanks!


BTW- Taylor hi-energy wires don't fit well. Some wires were too long.

 

There are a few of us that have the same problem.

You can check out my link for some stuff I've done to trouble shoot the problem:

https://www.thirdgen.org/techbb2/sho...hreadid=127625

I'm at the point I have related the problem to fuel. I've take most other things out of picture that can change the idle, so now I am thinking it is fuel. IF I unplug my O2 sensor, my surge goes from 500-1000 instead of the 650-800. So without the O2 input, the ECM has to RPM to adjust fuel.

I am surprized to see that you have a new O2 and it is still doing it. But I have read that other people had issues with the IAC, or a bad MAF.

I was hoping a new O2 would fix my problem, but if not, I am suspecting my injectors.

Mark.

 

The IAC is screwed into the throttlebody. You may have to remove some stuff on that side of the TB to get to it but you shouldn't have to remove the TB.

 

Bad News:
My 87 does the same thing. I have tried everyhting I can think of to fix it and nothing has worked. This is a tough problem to diagnose because it can only be caused by about ten thousand different things. Right now I am investigating a vacuum leak but have yet to find one, I am only at about 17" at idle.

Good News:
Cleaning the IAC is easy. You don't even need to take it off! Take off every thing up stream of your throttle body, ie. your maf and all that ducting that goes to your air filters. Now start it up, yes it will run like this, and spray some throttle body cleaner in the IAC port. This is a small hole located between the throttle body bores torwards the bottom of the front side of the throttle body. Give it a number of 5 or so second sprays. Bolt everything back up and rest your ecm to get rid of the MAF code that this will throw. total time 10 min.

Peice of cake, if this solves your problem completly though you can consider yourself one lucky 3astard.

 

Dustin,

Check this thread out ... might offer some ideas ... I am going to check mine out.

https://www.thirdgen.org/techbb2/sho...571#post891571

Mark.