Ok, I've given my car a tune up (92' 3.1) and changed the fuel filter to try and achieve a better idle. It idles rough and stall when i am on the breaks at a light but runs fine when i'm accelerating or just driving. If anyone knows whats up or has an idea please help.

thanks

 

I have that erratic idle too. It's been there pretty much since I've had the car. I was told that pretty much all of our cars has it. I have the problem with it dying at lights and stuff too. I was told to check the IAC valve. That could be the problem on that.

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Red 1986 SC, 2.8L, rebuilt 700R4, 3.42, t-tops, 167K miles and counting, K&N air filters w/ removed air baffles, hopefully more to come!
RIP #3

 

Carbon buildup can cause an IAC valve to stick and it can cause the EGR valves to stay open a little at idle. Try cleaning the IAC and EGR by either taking them off and spraying cleaner or used some type of injector cleaner in your gas tank to clean up the EGR valve.

 

Use higher octane...It runs a lot smoother

 

A major tuneup should be done; this will eliminate any "common" problems (like a cracked spark plug wire or fouled plug). This could be a bunch of things; but checking the IAC does seem like the right way to go.


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-Tom P (Hot rodded 1986 Firebird 2.8l)

 

If the above dosen't work check the wires going into the EGR. The 3.1L use a digital EGR. The wires are getting kinda old by this point and may have lost some of thier insolation and grounding out. There is a smal plastic cap covering ware the wires go in the cracks may be under that cap. just make sure you don't crimp a wire when you put the cap back on. I used eletrical tape and it cured my bad wire problem.

Another sorce of cloging is the EGR gasket at the intake. pull it off and use a little B12-Chemtool to clean it up. You can reuse the gasket becuase it is a pretty stiff compond, and it is a dealer part. you can't find it in the part store.

If all else fails replace the EGR, or at lest the solinoid that opens the valve. If you want a brand new one they coast abotu $250.00 (OOOCCCHHHH). I picked one up a scrap yard that pulls and test them for $100.00 . The only difference in my case was that my EGR was keeping the car from starting with out pressing the gas pedle. After that it couldn't idle.

If you replace it geet ready for a "fun" job. The tube that goes to the intake is a felxable meatle tube and doesn't all ways align correctly with the bolt holes. i spent the better part of an hour trying to line the dam things up.

 

I use high octane gas.....but i was thinkin my problem would have somethin to do with compression since my car has like 190,000 miles on it with the original motor. Isn't high octane gas harder to compress? Also i have replaced the iac valve and it hasn't seemed to help. It almost seems like i have poor fuel pressure or something. How do i check that?

 

My car has a new motor , well rebuilt .But it still idles like that . Does not really bother me .Its kinda lopey sounding ...When my cousin first heard the car after the new motor he asked if I had a cam in it ? I said no , and my Uncle said its loping lol ...