1G 1991 Eclipse GSX idle problems

[siciliankid92]

Just bought an 1991 GSX for $1500. It has a few problems. Car starts up great runs good for about 10 minutes then the idle starts going up. I drive it around for about 20 minutes idles about 3000 rpms in neutral. I have fixed the o2 sensor people have told me the fuel to air ratio was bad. I honestly do not know a lot about cars, just enough to get me by. So.. if I sound stupid don't laugh everyone starts somewhere.

 

[dsm92gsx]

i would replace the BISS screw if you haven't already. no need to worry about not knowing, just learn as you go. Hell I'm a noob to turbo'd cars and dsm's so welcome

 

[siciliankid92]

Well where would that be located? I was also told it could be the air control valve?

 

[talonalex92]

If its doing it when hot check the FIAV, its the coolant regulated unit under the throttle body. IAC could be an issue. The BISS screw is on the front of the throttle body across from where the cable would be.

 

[Abe'sGST]

Usually when the IAC valve stops working the idle stays constant with cold or hot engine...couls still be signs of it going bad though

 

[camas90gsx]

When i had idle problems in the past it mostly had to do with leaks,preturbo and after.Do a boost leak test and see if you have any leaks.If you are saying you have bad a/f readings then most likely it is a vacuum or boost leak.At one point my idle went from anywhere between 850-2600 and it turned out to be a major leaqk at the throttlebody.It was so bad that i would get crazy lean readings at idle and way rich at wot.Basically your computer is trying to account for the leak and adding and taking away fuel.Either that or it is your idle speed controller.Does the idle surge up[ and down or just stay constant? Another thing to check would be your throttle cable and see if it is functioning properly and not sticking or getting hung up.

 

[siciliankid92]

You guys are a big help. When I start the car its constant around 950-1000 rpms, but as I drive around town its gets higher but it stays steady. It doesn't bounce around. I continued driving one time it got up to 5000 rpms just at idle it stays steady there. It's really frusterating.

 

[talonalex92]

5k? Is your throttle cable or plate binding? Theres no way the iac or really anything could raise it that high without it shutting itself down or running like complete shit. Even if you adjusted the biss all the way out, and opened the iac all the way open I dont think it would go any higher than 3k. Check the cable and throttle plate first man.

 

[siciliankid92]

It doesnt run like that right after starting it up though. That's why I dont think its that stuff. I can start the car and have it sit and idle for about an hour and have it stick at 950-1000 rpms. It's when I drive it around it starts rising but it doesn't surge or anything.

 

[johnmel]

It doesnt run like that right after starting it up though. That's why I dont think its that stuff. I can start the car and have it sit and idle for about an hour and have it stick at 950-1000 rpms. It's when I drive it around it starts rising but it doesn't surge or anything.

Mine did the same thing turned out to be the egr

It doesnt run like that right after starting it up though. That's why I dont think its that stuff. I can start the car and have it sit and idle for about an hour and have it stick at 950-1000 rpms. It's when I drive it around it starts rising but it doesn't surge or anything.

Mine did the same thing turned out to be the egr but read this it will help and tell you everything Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)

But I just saw you have a 91 and I believe those came stock with the egr block off

 

[pauleyman]

91 did not come stock with egr blockoff. None did. It's not possible for the car to exceed 1500rpm with the throttle closed. FIAV, ISC, none of those are capable of it. You'll idle cycle. That being said start with the throttle cable as one of two things is likely. The throttle is actually open (sticking or cable sticking) and/or the idle position switch is bad or disconnected. In my opinion it's likely the cable. They have been well documented for wear/sticking etc as they get old.

 

[johnmel]

I thought I read that some where