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post #1 of 5 Old 02-29-2020, 08:08 PM Thread Starter
grenade252
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Idle issues

Should I replace my MAP sensor next in my search for idle problems?

I've already replaced the IAC, TPS, and Cam shaft sensor, over the last year. Also had a smoke test done for leaks. I used Mopar parts.

My rpm will often drop from idle to around 100-200 rpm, engine will shudder, then return to normal. It always fluctuates about 100-200 rpm when idling. It'll drop whether ac is on or off, on the brakes or parked. Sometimes when it drops hard and recovers, something will tap like the sound of the EVAP solenoid.


2000 4.7,3" Kolak Exhaust,3" IRO,Skyjacker M95,Superchips Flashpaq,Powerstop brakes,Addco Swaybar
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post #2 of 5 Old 03-01-2020, 08:53 PM
Bigrigr
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What codes in the PCM? Any lights on on the dash? Whats your fuel pressure while you are running? Some say that the Cam and the crank sensor should be changed at the same time. Might not be a bad idea?

'00LMTD-4.7l,242hd,D30,D44A,3.73's,True-trac front,Spartan rear,4" short arm lift,JK'sW/32's
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post #3 of 5 Old 03-01-2020, 09:36 PM
99SK04GTX
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Have you done a thorough cleaning of the throttle body?
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post #4 of 5 Old 03-02-2020, 08:18 AM
Waterluvr
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There are 4 driver circuits in the pcm that control your Idle Air, and bad IAC drivers in the pcm are very common for these symptoms and almost never set a hard or pending code.

You can usually see a bad driver on one or more of the 4 circuits using a digital test meter when there is a large deviation like this from the target idle value, send me a pm with your email if you want some help troubleshooting those it's most likely the source of your problem after all the parts you replaced didn't work.
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post #5 of 5 Old 03-02-2020, 05:01 PM
Double E
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I like what Waterluvr suggests.
For another easy test, next time this happens, open the hood with engine running and give the alternator a tap with your hammer.
No need to go after it like it called your sister fat, but make sure it knows you hit it.

That should make idle return to normal instantly and will confirm that the alt is on the way out.

'04 Freedom Edition HO & '04 Overland HO (previous '00 Laredo 4.7)
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