Low idle even after cleaning and replacing IAC

[LukWarm]

Hey guys,
I've got a 2000 Sahara with about 160k miles on it. Recently started having issues relating to idle. It started by idling rough or not idling on and off on mostly hot starts, being fixed most of the time just by restarting. More recently, it changed into it starting up fine cold, but after restarting a few times over (like 5 or so) it would either not hold idle or be really rough and low, and the engine didn't have to be hot either.

I cleaned the throttle body thoroughly and it started to run smoother almost immediately after. It's now a month or so after doing that and I can't get the car to idle unless it's warm. Replaced the IAC valve about a week ago. First startup it ran beautifully, smooth idle going between a couple different spots, from 1000 rpm to 1500. I followed the instructions on the box to "calibrate" it with the ecm, going above 40mph for at least 5 minutes, and now it won't idle unless its warm. It usually sits around 5-600 and rough. Any help is appreciated.

 

[Ryjedavis]

If you are still looking for an answer, try the TPS. I have a 2000 with 180000 miles and had similar symptoms. Replaced TPS and good as new. mine never threw a code - a testament to how awesome these engines are that they keep on trucking despite sensors going bad.

 

[Jerry Bransford]

As above, a bad TPS can also cause that problem.

But... when you cleaned the IAC did you remove it to clean it, or did you spray throttle body cleaner into the throttle body body at idle rpms? That will clean both the IAC and its air passage/orifice too. If just the IAC gets cleaned, that will leave its air passageways inside the throttle body dirty which can still restrict air flow into the engine,

 

[Ryjedavis]

Agree with Jerry above. Before I replaced the TPS I shot a whole can of throttle body cleaner into the IAC while the engine was running based on an earlier thread of his. Didn’t solve the problem completely, but it definitely idled a whole lot better. When I started it bogged down with every spray and by the end of the can of cleaner it was working so well the engine wouldn’t change at all with a spray. I’d definitely start with that if you didn’t do it that way - throttle body cleaner is cheap.

 

[LukWarm]

Honestly forgot I posted this thread! I tried replacing the MAP sensor and got absolutely no change. After returning that, I bought a TPS about a week ago and just installed it the other day. Once the engine is warm, idle is rock steady at 750. On top of that, my throttle response feels a lot smoother and powerful. I bought one off ebay and so far so good. I'm hoping to avoid the $60 for the Mopar part.