CRP.NWJEEP

Hey guys having a weird idle issue with my 00 classic.

I did a search but didn't really find anything. Anyway I just had a new long block put in about 1k mi ago and it's making a funny pulse while idling.

It's a pretty intermittent problem, usually happens when cold.. But when it does happen in any one driving session the pulsing will occur from cold start all the way through the trip to destination.

Problem: after starting with the motor still cold it will idle about 850 but pulse every 15-20 secs about 400 revvs. Even while driving you can still feel the surge of the motor (even while pressing the gas for 1/4 throttle or whatever)
It does seem to happen more often with the heater on, I don't know about the a/c though haven't tried it.

When I picked up the car from the mechanic (certified mech. guy we know who did it in his garage for me) he said that I might need to check the idle motor, does this sound like a viable option? Don't get me wrong that is the first thing I would imagine would be the issue, but just wondering if anyone else has some input on what it might be.

Thanks for any input guys!

Colter

Radi

I assume you re-used all the sensors and electronics for the swap? They were functioning properly before the switch?
I'd guess either the IAC is sticking, or another sensor has gone south and the PCM is chasing it around. Any other oddities that you've noticed? Any codes stored?

Tfox671

My egr was acting up on mine and it did that. Also, when my harmonic balancer went bad, it had a rough idle.

salad

None EGR on 2000, that was over with when Chrysler redesigned them.

What Radi is saying about the sensors is probably where you'll find this issue. The IAC could indeed be dirty but the ECU moves it based on input from the sensors. Disassemble the throttle body and give 'er a clean, tons of writeups on here covering that, you need some small hand tools, soft tooth brush, and throttle body cleaner. It could also be nonsense like the MAP or O2 sensors so any other symptoms might be related