Poor Idle Speed When Warm

swimmingly · 03-03-2006, 07:55 AM

My car always seems to have a difficult time idling at a above 900 rpm. When the car is cold, the idle hangs around 950, which feels right (but, I think it's suppose to idle higher when cold?).

However, after driving the car around and getting it nice and warm, when I idle, the rpm drops down to around 600 and I can keep hearing the engine sound like it's struggling as the rpm fluctuates up and down between a 500-700 rpm range, which it eventually levels out to around 700 rpm.

Anyways, I'm thinking I should fix it soon because I'm tired of the struggling sound and vibrations when the car is warm and idling.

Does anyone have any suggestions as to where I should be looking? I have plans to replace the following during spring break:
1. ISV - add in the venturi delete while I'm in there
2. TPS
3. seals on the TB - Arnnworx's kit

Anything else I should look at?
Thanks

IanS · 03-03-2006, 11:28 AM

A bad TPS could cause you some problems. Have you tried backing out the idle adjustment screw a bit? 600 rpm idle is really low. I get about 950 both cold and warm, though maybe its 1000 cold.

If you want to come by sometime, I can pressure test your intake with my air compressor and that'll find any leaks you have.

Lawrence Coppari · 03-04-2006, 06:05 AM

I vote for idle stabilization valve. Had to replace mine a few months ago. Idle speed was too high when warm and too low when cold. Unfortunately, valve costs about 150 bucks.

You should hear a click from TPS just as throttle closes. Like IanS said above, that could also be the problem.

IanS · 03-04-2006, 12:30 PM

You could try pulling the idle stabilization valve and cleaning it if you find out thats the problem. I believe some people have had success with that.