Re: Surge Problem (archive)

Thanks. ICV was replaced, Tech said he checked for vacuum/intake leaks. Temp seems to be normal, wonder if it would be worth replacing thermostat to see if it made a difference.

It also seems to be more prone to this behavior at certain times, like when outside air is muggy & somewhat cool.

Steve:

Check:

1. Thermostat. What is your temp gauge showing you? Is the temperature staying at normal (about 12 o'clock) during highway driving. A low temp will 'mess with' idle. I had this issue with my E30 and replaced the ICV while trying to find it.

2. Bad ICV. This is under the plenum. It can be cleaned to prolong life, but eventually you're going to have to replace it.

3. Vacuum leaks on intake. I think this is unlikely, but it is easy and cheap to check. Is there any high-pitched noise when you lean itn towards the engine? Spray carb cleaner around the suspect areas and see if the idle fluctuates.

Neil Deshpande
http://www.neilwerke.com

***

Have been having an intermittent problem with surging/high idle, ONLY when a/c is turned on. With AC off everything is fine.

The beast bucks & suges mildly when I try to run a steady speed where the motor is turning 2000 rpm or so. When I stop, the idle hangs at 2200 RPM. Blipping the throttle sometimes causes it to return to normal, but not always. If I leave the cluth engaged as I slow down util RPMs drop below 1000 before depressing the clutch it idles fine. If I do the same thing but only to 1100 rpm or so, RPMs climb to 2200 and stay there until I mess with the Throttle. Also, RPM will climb to 2200 RPM on start up, sometimes stays there, other times drops to normal after a few seconds.

Just had an insp II, which actually worsened the problem. O2 sensor and Idle Control Valve were replaced.

My tech thinks it might be the brain. Anyone here had this particular problem?

Thanks in advance.

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