Very Intermittent Idle Problems

[ddas]

I have a 2000 Sl1.

Sometimes it idles very high (2000-3000 rpm). If it starts doing this, i can turn the car off, and on again and it'll return to normal. Once it's in this high idle "mode", the only solution is to "reboot" the car. The computer is not throwing any codes.

The problem is so intermittent that you can drive for a couple days and not see it. The only explaination the dealer can think of is the temperature sensor is bad causing it to think it's very cold outside. I've replaced that temperature sensor and the problem still persists.

I pulled out the throttle position sensor and it seems to work fine. Is there anything else that could cause the ECM to think it should idle high?

Dave

[SWScorch]

I don't have an answer, but my car (2001 SL1) does the same thing so I'm bumping this thread so we both have a better chance at an answer.

[RangerRover]

You may need to replace the Idle Air Control solenoid. It may be sticking.

Try removing the throttle body and cleaning it thoroughly - the carbon/gunk may be causing the valve to stick.

[Mic_]

any luck in resolution?

[nwmike]

The idle air control valve controls the idle speed. On my '99 it is below the TPS, held in place by two screws. (you will need a star bit or allen wrench) You can pull it out and clean it with carb cleaner, or replace it for about $60. I replaced mine and it did slow my idle down a bit and I noticed that the engine slows down sooner now when I take my foot off the gas. However it still runs faster than what I consider normal when shifting between gears, but the car always has.

[bryank930]

I had this problem also. Pull the intake off of the throttle body, when you look into the TB, you'll see a hole on the bottom. Spray some throttle body cleaner in there WITH THE CAR OFF. Also open the throttle, and spray off the backside of the throttle plate. That cured mine 100%.

Bryan

[nwmike]

Just thought I would mention this to you... another member suggested I spray carb cleaner or brake cleaner along the intake manifold gasket to check for a vacuum leak because of a misfire/rough idle condition I have (my car idles too fast also). I tried it last night and right away my idle speed slowed down and smoothed out a bit and I could smell the burnt vapors from my exhaust... bad gasket/vacuum leak indeed. I will be changing the gasket tomorrow and will report the results. You might want to try that test.

[richpin06]

Originally Posted by ddas

I have a 2000 Sl1.

Sometimes it idles very high (2000-3000 rpm). If it starts doing this, i can turn the car off, and on again and it'll return to normal. Once it's in this high idle "mode", the only solution is to "reboot" the car. The computer is not throwing any codes.

The problem is so intermittent that you can drive for a couple days and not see it. The only explaination the dealer can think of is the temperature sensor is bad causing it to think it's very cold outside. I've replaced that temperature sensor and the problem still persists.

I pulled out the throttle position sensor and it seems to work fine. Is there anything else that could cause the ECM to think it should idle high?

Dave

You might want to double check that throttle position sensor.Next time you have a high idle.Tap on the TPS.See if the idle changes.If the idle changes replace the TPS.