2.5 idles low, is it the Idle Air Control or the Throttle Position Sensor....? Both?

RawLo · 06-25-2009, 02:12 PM

Hi guys... this is my first time posting on here, although I've been reading your posts for a while now. Very helpful and informative!

I have 2001 Wrangler, 4 cyl 2.5L.

For a few weeks now, I've had the low/ rough idle problem. It seems to start up fine. I will drive it for a minute or so... as soon as I stop, the idle speed will drop to 400-500rpms.... it will stall out at that point. If I stop but keep giving it gas- the rpms will stay up and things are fine. It will not stall or buck while the throttle is engaged. Only at idle...

No check engine light, by the way.

I cleaned out the opening to the throttle body and the plate, pretty dirty.

Upon the advice of my mechanic- I changed the Crank Sensor. (When the problem started happening, the engine would stall at idle and wouldn't start back up. It'd crank, but no spark.)
So I changed out the Crank Sensor and am still having the low idle problem.

I read many posts here about cleaning the Idle Air Control. I tried that, but the problem persists.

It's intermittent, but seems to happen less after a drive on the freeway.

My friend had the exact same symptoms on his 2002 Toyota Tacoma truck. He also tried a few fixes before changing out the TPS. He said that solved the problem and may be the cause of my woes.
However, when I looked at the part he bought- it was a TPS with an Idle Air Control attached to it- one single unit!

This makes me wonder if my problem lies in the TPS or the Idle Air Control. Is there a way to tell if it's either/or? Cleaning the IAC didn't resolve it, but I couldn't tell if the unit itself was faulty just by looking at it.

Money is an issue for the next 10 days and I can only afford to change one of those components today. Should I try one over the other? I'm leaning towards the TPS.

Thanks in advance, fellas... I appreciate any help.

Brian

**GOLENJEEPTJ** · 06-25-2009, 02:40 PM

Try pulling the IAC on throttle body first and cleaning it with some throttle body cleaner (cheap) $10.00 under bucks. Sorry re read your post you've already done that.

RawLo · 06-25-2009, 02:49 PM

Thanks for the reply!

Yeah, I removed it from the throttle body and cleaned it up two days ago- but it didn't change things. That's why I'm thinking it either needs to be replaced, or the TPS needs to be replaced.

**GOLENJEEPTJ** · 06-25-2009, 03:05 PM

Yea the only bummer is no codes being thrown?

sdmoose429 · 06-25-2009, 03:08 PM

Quote:

Originally Posted by RawLo

Thanks for the reply!

Yeah, I removed it from the throttle body and cleaned it up two days ago- but it didn't change things. That's why I'm thinking it either needs to be replaced, or the TPS needs to be replaced.

Replace the IAC. Or, have it diagnosed by a pro with a scan tool. They can use the scanner to run the iac through its full rnage and see if it sticks or what.

The iac is what controls the idle speed. The tps just tells the pcm how far open the throttle is.

Good luck.
Moose

RawLo · 06-25-2009, 06:38 PM

Well dudes... I changed out the Idle Air Control and I think we got a winner! Of course I won't know for sure until I drive it for a couple of days and nothing happens... but so far, so good. I drove to the gas station and the idle speed stayed around 800-900. At a complete stop, it would dip down to about 700.

Is there any kind of reset that I need to do? A "guide" that came with the part mentioned how the idle speed may initially be abnormally high- but that did not happen. I had the battery disconnected when I did the job, it took maybe 30 minutes to complete.

Thanks again, guys...