Hey all, I have a 95 GT that is still all stock. A while back I noticed that the idle increased to about a 1000rpm in gear (its an automatic) and about 1400rpm in Park or Nuetral. The engine light would come on every now and then but would not stay on. If I shut the car off and restarted it then it would be ok until I drove it. I did a diagnostic test and it came back with no bad codes. I pulled the IAVC and cleaned and it helped a little bit so I replaced it with a new one. It was running normal for about the last two week since I replaced it and now it is doing it again. Do you have any ideas? I hate to start changing out sensors and it not be the problem. If you need more info please ask. The engine has 136,000 miles, stock exhaust, and it had a tune up with new plugs, wires, cap, and rotor about a year ago.

 

Check your vacuum lines. Sounds like maybe a vaacuum leak.

 

You mean IAC>? Check IAC, MAF, check for vacuum leaks, because that is quite a bit high. Check your tb make sure its not all gummed up too.

 

I'd second the TB being gummed up. If there is black goo keeping the TB butterfly from fully closing, it is sending a signal to the TPS to increase the "idle". If that all checks out, then slowly check over the engine looking for vacuum leaks.

When you changed the IAC, was it an aftermarket? If so, grab your directions and make sure you installed it right. Reason I say is that some aftermarket IAC valves you have to flip over for them to work correctly. I plead the 5th on this one.....

 

Thanks guys I will check out the TB this morning. The IAC was installed correctly. It even fixed the problem for a couple of weeks but it is right back where it was before. I know it is not a vacuum leak as I checked for that first before I checked the IAC. I have not checked for a gummed up TB though. Hopefully that will be it. I will let you all know as soon as I find out something.

 

Yeah, I'd be interested to know. Should be as simple as some Gumout or the like.