High idle until stop.

[RTH]

2004 Sport, 3.7 manual transmission.

I've been reading up on this issue and have seen suggestions to change certain sensors or look for vacuum leaks, etc. But no definitive answers that fit my symptoms.

That being said, it's idling high at around 2000 RPM when I either engage the clutch or put it in neutral. When I come to a stop, it idles back down to normal. The difference with my issue is that it only does it until the engine gets to temp. after that it idles normally at all times. None of the issues I've read about met that particular criteria.

So before I go changing sensors and hunting down vacuum leaks, is there a particular direction I can be pointed in due to this seeming to be tied into engine temp? This engine does have a throttle body spacer on it, so I'm not sure if that plays into the problem.

 

[LibertyTC]

It would be helpful if you would add the year of your KJ to your signature line. Are we talking about a 2004?
Can you read what the OBD2 temp sensor is reporting back regarding the temps while warming up / or when acting up?
I would return it to stock and remove the throttle body spacer for starters. (known issue potential leak right there)
Spraying some carb cleaner around throttle body base does the rpm change at all?
Check to make sure that throttle body plate/butterfly is all clean & not binding or sticking, with a smooth operation, and able to fully close.
Possibly other members more familiar with a manual stick may be aware of something on the manual transmission as a potential issue.
The IAC (intake air control) generally controls the idle and may need cleaning/ or replacement?

 

[RTH]

Whoops. Forgot to mention the year. Yep, it's a 2004.

Ok. Thanks for the advice. I'll see if the IAC from the 05 is a match and do a swap if it is. Being that it only does it until the engine gets to temp, and runs fine otherwie, I was hoping to rule out a leak.

 

[LibertyTC]

Ya no problem, refresh your screen, I edited in monitoring the temp sensor, to see what it is reporting while warming, I wonder if the temp sensor may be out to lunch.

 

[RTH]

Yeah, I can monitor the temp but it might take a few days. I'm not in a position to buy a scanner at the moment, but a friend has one that I can borrow. In the meantime, I'll check the IAC and maybe just swap temp sensors if I can get them out.

 

[RTH]

It was the IAC. Very dirty and had some debris inside of it. Swapped with the IAC from the 05 donor. Easy peasy. Thanks for the advice.