Cold start rough idle and start/stop triggered

[canyonrat]

Seeing this on cold starts in the morning where the engine will have a rough idle for a minute or so, eventually the auto start/stop dash light gets triggered, and idling starts to calm down after running 90 sec or so.

Then, if I turn the engine off, wait a second, then re-start it idles smoothly, and I can drive off with everything normal. Auto-start/stop works fine even. I don't see this as a start-stop problem, more as an intermittent very rough idle on start that is so rough if I try to back out right away the engine does not want to push the truck back.

I cleaned throttle body, and the MAT and MAP sensors. Ran a round of Techron through the engine. Still a problem, torn between paying to have the plugs done (I don't want to wrestle the whole manifold removal) or taking to the dealer for a diagnostic. Anyone with insight?

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[Wharton]

I’ve seen this a few times. Cold start rough idle that clears after a restart usually points to a sensor or fueling issue, not plugs. Manifold removal for plugs is a pain but at your mileage they usually don’t cause this. I’d lean MAP/MAT wiring, coolant temp sensor, or a bad software cold-start calibration. A dealer scan for stored or pending codes and a software check is probably money better spent than throwing plugs at it.

 

[Hoist]

You can try holding down brake pedal and gas pedal at the same time and press the start button. It will motor without starting.
press start button to stop it turning over then start normally. So far, that’s been working for me.
Not sure if it’s oil pressure or what but I don’t get the misfire light or A light by doing this.

 

[canyonrat]

Mods thanks for relocating my thread and thanks @Wharton and @Hoist for the replies. It's been at the dealer since Monday now (It's Wednesday) and they currently can't reproduce the issue. The weather got a little warmer in TN now when it was really cold it was doing this every day or multiple times a day with the rough idle. There was a misfire code read.

 

[Hoist]

Well good luck. I suspect my issue may have something to do with a head gasket but I have to check compression, driver side is a pain.

 

[canyonrat]

Well, the dealer is saying they found coolant in one of the cylinders and a head needs to be replaced. So they recommended replacing both "while they are in there". I'm at 75k miles and it's a 6 year old truck so I'm out of warranty... time to find out if "jeep cares" about me or not.

 

[Hoist]

Man, that sucks. Good luck with JC. Maybe they’ll help. I dont know if it’s a head or just a gasket on mine but I just got it going again with a new cam so I’m gonna stick with motoring before starting. I’m still considering a different engine option.

 

[NC_Overland]

I’m sorry to hear that. Unfortunately Jeep cares quit helping after Stellantis took over. You’re pretty far out of warranty for a goodwill repair anyway.

 

[1herm4]

Same here, 87k miles and needing a head gasket. Currently at an independent shop that works on many jeeps. He said he sees one a week with bad head gasket. Someone needs to start a class action lawsuit, this isn't normal!

 

[canyonrat]

Yeah I thought about extracting it from the dealership after diag but it was limping in with high temp warnings on a short drive there. It’s sad and makes me want to sell the truck when it’s done. Not sure if the repair is signing up for another 60-75k before failing again or if the new heads solve a manufacturer defect. I’d sign up for that class action.

 

[1herm4]

Yeah I thought about extracting it from the dealership after diag but it was limping in with high temp warnings on a short drive there. It’s sad and makes me want to sell the truck when it’s done. Not sure if the repair is signing up for another 60-75k before failing again or if the new heads solve a manufacturer defect. I’d sign up for that class action.

I had mine towed in just to insure not to overheat and potentially cause additional damage.

 

[JeepCares]

Yeah I thought about extracting it from the dealership after diag but it was limping in with high temp warnings on a short drive there. It’s sad and makes me want to sell the truck when it’s done. Not sure if the repair is signing up for another 60-75k before failing again or if the new heads solve a manufacturer defect. I’d sign up for that class action.

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[1herm4]

Sorry but if Jeep really cared....there would be a recall for head gasket issues.
Extended warranty from Jeep is thier answer to a known issue. They want you to pay for this warranty to help recover their loss. Then you try to use your warranty only to for the dealership to drag thier feet blaming Jeeps warranty claim process.
I value my time and Jeep only cares to waste my time. So NO, Jeep doesn't care! I'm sure there has been some cases on this forum where customers had thier Jeeps repaired with the of "Jeep Cares" member but .....

Where can I send my invoice for reimbursement for my repairs?

 

[canyonrat]

I have asked the same question as above, I had to pay out to get my repaired vehicle even though the process took weeks with part orders and my tech "out for training". Jeep Corporate threw back their hands and said it was up to the dealership. The "case manager" was useless. The dealership said they can only submit Goodwill Grid if I bought the vehicle there and had every bit of service done there for the life of the vehicle. So they proceed to finger-point at each other, and the customer is left in the middle holding the bill for something that is an obvious manufacturing quality issue. So... JeepCares, where do I send the invoice for reimbursement?

 

[Mtverini97]

@canyonrat @1herm4 I am having the same issue. 2020 Sport S 70k miles. The auto start/stop light came on a few months back, and I thought nothing of it. About a month ago, the CEL came on, I diagnosed the issue as low coolant. Same rough idle at start but that would smoothe out after driving for a few mins. I topped it off and a few days later, the CEL turned off. Knew it was just a bandaid for a bigger problem but was too busy to take it in. About a week ago, the CEL started flashing on a cold start but now it came with a sweet exhaust smell. Oh no. The rough idle on cold start had been going on for like 3 weeks at this point . Let it sit idling for 5-10 mins and the flashing stopped but then i knew i needed to get the code. Registered as P303.

The coolant thats been leaking must be getting into that cylidner. I've read just about every forum on this topic now and all signs lead to head gasket issue. BIG $$$ repair. Im taking it to the dealer this weekend and will open a jeep cares case but your story does not give me hope, nor do the countless other stories ive read.

This seems to be a major issue for these trucks popping up around 50-75k miles based on all that ive read. Ill really be considering selling mine if jeep doesnt reimburse. Dumped way too much $ into this thing for a manufacturer who does not stand behind their product, with KNOWN defects. Id be happy to join a CAL as well; should probably get that going now, as Im sure the 2021-2024 models will soon be experiencing this "hidden egg" as their miles creep up!

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