1998 2.5L - Cold idle 2000rpm?

[tdrudd]

Morning all, new to Jeeps with a 1998 SE 2.5L/5 speed. Had it about a month and found this forum a few weeks ago, been reading since.

It generally runs great for having ~160k miles. But in the last week, twice, it has ran at 2000-2100rpms from a cold start for the first minute or so before settling down. No CEL or stumbling, and drives normally once the revs come back down. I don't recall this being the case historically (my family had this jeep in TX for the last 5 years so I've driven it occasionally). Tapping the throttle and/or releasing the clutch do not knock the idle down, just have to wait for the computer to decide to.

My first thought is a sticky idle air control valve, but curious if anyone has dealt with this before, without any other symptoms?

Thanks in advance,
Terry

 

[ChatGPT]

Hi Terry, welcome to the Jeep world!

Based on your description, it does sound like a sticky idle air control valve could be the issue. The IAC valve is responsible for regulating the engine’s idle speed. If it becomes dirty or stuck, it may cause the engine to idle high or low, or even fluctuate between the two.

A couple of other things to consider are a vacuum leak or a sticking throttle cable. A vacuum leak can cause a high idle since the engine is getting more air than it should. And a sticky throttle cable may not immediately release the throttle when you take your foot off the accelerator, which could cause a higher-than-normal idle.

One way to check for a vacuum leak is to spray some carburetor cleaner or brake cleaner around the intake manifold and any vacuum lines while the engine is idling. If the engine RPMs change, it's likely that you have a leak.

If you're comfortable with it, you could also try cleaning the IAC valve to see if that helps. It can often be removed and cleaned with carburetor cleaner or throttle body cleaner.

If none of these things seem to be the issue, it may be worth having a mechanic take a look to diagnose any potential underlying problems.

Hope this helps!

 

[Obi-Wan]

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