mlm0

89, auto trans, 50,500 miles, stock condition

I have posted many times on this forum about the rough idle i have had since buying my vette fours years ago, or 7000 miles ago. I wont go into everything i replaced of adjusted trying to fix it with no luck.

After reading all i could find on this forum, and others, i stared thinking it might have something to do with my egr valve not seating tight, even though I had it replaced it along with FSR, and injectors right after buying the car by a local corvette shop. I could not afford to keep taking it back to shop because of the possible cost to find the problem, so i have been doing it myself, even though engine repair is not my strong point
By the way the egr valve passed all the test i performed on it using vacuum gage

Today i unbolted the egr exhaust tube from where it connects to the right side exhaust manifold, NOT were the tube connects to the rear area of the manifold. I bought a tube block off plate from TPIS, sandwitched that between two gaskets, and bolted it back up. My thoughts were that this would have the same affect as removing the egr valve from the manifold and replacing it with a block off plate, and it was much faster because i did not have to remove all that stuff to get to my egr valve

I started it up, and guess what, it has never idled so smooth, and no code 32 and no exhaust noise

I just hope it continues, and if it does, i will later fix the problem by cleaning the carbon around the egr mounting area on the manifold so that the valve can seat fully, cutting off exhaust gas when not called for

I hope that this info just might help someone else

I love this forum, once I decided to have thicker skin

antfarmer2

Good job some can be a PITA

jv9999

I did the same thing to mine. If it's not throwing a code you probably have an aftermarket chip that's programmed out the EGR anyway.

Benny42

Your driving style may keep the EGR code from ever setting. My '86 has long tube headers
and no EGR provisions. I almost never get a code, only on long road trips. My attitude is
"don't fix what ain't broke". If it starts throwing codes, there are ways to address that.
Glad you found it.

mlm0

If it starts throwing code, I will burn new chip eliminating the egr code. I can do some changes, just don't know how to re tune for best performance changes

Silver96ce

Glad you found the problem and, more importantly, thanks for posting it.
Too often someone will post about a problem and never post back with what was actually wrong and what fixed it.

I also have to give you a double thumbs up for your persistence and "never give up" attitude. You have been dealing with and over time finding and repairing the problems with the car. This problem I seem to remember has been plaguing you for a loooong time.

mlm0

Yes it has and thanks to everyone along the way who assisted me with offering possible solutions

Hope I'm able to help others at some time. I try to read all post in all areas of C4's