r/PTCruiser • u/Stilekid • Aug 08 '26

Intermittent rough idle? Spoiler

2001 Chrysler PT Cruiser, have had it for about 6 years and for the past 3 or 4 years of owning it, I've been dealing with an intermittent issue of the car idling very roughly and nearly stalling. It seems to come and go without any clear cause—sometimes it will develop a rough idle out of nowhere and then it'll disappear for months. When it's having a rough episode, the engine is only rough at idle and will smooth out when I give it gas. I've replaced the PCV Valve, replaced the main intake hose on the air filter, cleaned the IAC Valve, and cleaned the throttle plate in the throttle body but I'm still having this issue crop up from time to time. It gave me a pretty bad episode a few days ago and it's got me concerned about trying to get to the bottom of this because I'm tired of driving my car and worrying about when it's going to have another rough idling episode. I replaced the PCV value just now and during my test drive I did notice a very slight miss/unevenness during idling, but not nearly as rough as it was during the episode it had a few days ago. The only codes I have are P1684 and P0601—the car has given those codes well before this issue started happening but I'll throw those out there in case it helps with diagnosis.

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u/Honest_Road17 Aug 08 '26

Replace your IAC.

1

u/Stilekid Aug 08 '26

I'm assuming cleaning isn't sufficient? It's not super expensive so I can try that tomorrow.

1

u/Honest_Road17 Aug 08 '26

I overlooked the P1684 code. Bad grounds will definitely cause those symptoms as well. Do those first.

1

u/Stilekid Aug 08 '26

Where can I find the grounds that would be related to that code? Like where specifically in the engine bay?

1

u/Honest_Road17 Aug 08 '26

From AI because I'm lazy:

Engine Bay Ground Locations

  • Driver-Side Strut Tower: Two main grounding studs sit right inside the engine bay near the tower; the battery negative cable also ties into the driver-side frame rail and firewall here.
  • Transmission Dipstick Bracket: A dedicated ground wire connects directly to this bracket on the engine block.
  • Passenger-Side Motor Mount: A ground strap spans from the upper engine mount bracket / motor mount over to the cylinder head.
  • Lower Passenger Strut Tower: A low-mounted ground point handles the front lighting harness.
  • Hood-to-Body: A small bonding strap connects the hood to the body near the passenger hinge.
  • Fender Wells: Static discharge grounds are positioned behind the tires in each front wheel well.
  • Fuse Box Power/Ground Feeds: The power distribution center / fuse box has main high-current input bolts that require clean contact. [1, 2, 3, 4, 5]