Idles High

[chiuchimu]

1997 Eclipse Gs Auto

Over the course of several months this behavior has been increasing.

On Start, gear in park, the Idle will jump to 2000Rpms then come back down to 1200Rpms in 5 seconds.

If I give it a little gas, it will again jump to 2000 -3000rpms then back down after several seconds. Next, in drive, the rpm drops to about 800.

As I drive, the car seems to want to cruise at 30 mph even though I'm not stepping on the gas pedal. As I stop at a light, the will take a few seconds to idle down to 800 Rpms.

This behavior seems to be getting worse so I want to fix it while I can still drive my care. The engine runs very smooth and the temprature doesn't seem to be a factor.

Please please please help!

 

[stevo911]

Are your throttle cables too tight? When you check them make sure there is a little bit of freeplay.

 

[chiuchimu]

Yes my throttle cable is a bit loose.

 

[GRAVEDIGGER]

Maybe try cleaning your throttle body. I always have good luck just taking the hose off the inlet to the throttle body and spraying some tb cleaner which is avail at any auto parts store down the tb. Hold open the throttle and spray and wipe it out with a cloth. Then start it up and continue to spray it in the throttle body while keeping the rpms up so it doesn't stall. Keep spraying in short bursts. That will usually free up things in there and get it running/idling better. I have done just this simple thing on quite a few different cars with idle/surging problems and it has worked every time without having to remove the throttlebody or any part of it. Just an idea for a simple fix (hopefully).

 

[chiuchimu]

Thank you. I will try that and let you know.
Also, update my description. It seems like my car wants to idle at 1400 Rpms. That's what it does in 'Park'. In Gear it goes down to 900 -1000Rpms but I think its just the transmission load slowing it down. The engine runs very smooth. until a stop light. Then the rpm dips to 800 then rises to 1200 and settles to 900rpm - its like two things are battling for control of the idle speed.. This all happens in about 4 seconds after stopping.

My car doesn't have an idle screw. but the way my car behaves can be described as a perfectly fine car with the idle screw turned up too high.

 

[chiuchimu]

I cleaned out the TB and tested TPS, it was OK. I couldn't test my ISC because it has 4pin. there are no instructions for a 4pin test. But I cleaned it really good.

I started my car. no difference. I started spraying Carb Cleaner at different parts of the engine and hoses to test for leaks. I noticed that when I sprayed the EGR valve, the engine Rpm would lower` for a moment.

I replaced the EGR with a new one, noticing on removing the old one, the bolts to connect the pipe to the EBR were loose. -might have been a vacuum leak.

Now my car is almost fine, It idles inpark about 1100rpm(a little high) before it was 1500rom
in drive it idles 850rpm. its almost fixed.

I still have a problem, When I start the car it jumps to 2000rpms for a second before steadying off at 1100rpms. On stop lights the rpm would drop as expexted but would go up a small amount before coming all the way down to 850rpms

ex: driving rpm->2000->1500->1000->1100->850

In general, Gas-pedal-down response is great but Gas-pedal-up response seems delayed by a second or more.

Iv'e ordered and waiting for 2 new O2 sensors and a used ISC. What could be causing this throttle response?

 

[chiuchimu]

Update:

Idles still high and creeping higher. Looking for vacuum leaks. I sprayed Carburetor cleaner around the base of the intake manifold while the car was idling and it brought the idle down, almost stuttered and stalled. Each time I spray around the intake manifold gasket area I get a drop in engine rpms. But as the engine warms up, this effect goes away. I'm thinking it gets so hot the carb cleaner instantly evaporates.

Anyway, what ya thing? I'm thinking vacuum leak at intake manifold. But I want to be pretty sure about it. So guys, any reason its not a vacuum leak? Taking out the intake manifold is a B!tch. That stupid EGR tube alone is a nightmare! I don't want to the all that only to find the problem wasn't fixed!

 

[chiuchimu]

Found problem. Intake Manifold gasket was leaking.

 

[GRAVEDIGGER]

Congrats.... And way to stay with it and use your head.