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Wifes Patriot has rough idle but does not throw codes.


NAXJA Forum User
Leadville, CO
Her car has been pretty well maintained (by me) since we purchased it new. Its a 2009 with the 2.4 liter and CVT transmission.

Since we moved to Leadville CO last fall it has developed a loopy idle and sometimes stalls or lurches if you don't let it warm up for a few minutes before putting it in gear. Not sure if the elevation here has anything to do with it. Leadville is at 10,200 ft. The rough idle smooths out if it is put in neutral so maybe the engine mounts are bad, but that should not cause it to stall.

I cant find anything wrong with it. Took it to a repair shop and they could not identify the problem. It never throws any codes even with the stalling.

I am going to start by looking at spark plug condition and maybe checking the fuel pressure. Any ideas what I else I should check?
I think Chrysler had a reflash to address some of that. You would have take it somewhere that's capable of doing it tho. I'd expect to pay $100-150.

You could also try cleaning the throttle body.
I'd bet its the lead in the water up there.

it sounds to me like a spark issue. like a spark plug shorting to the head via a bad boot or something like that. they normally come and go with load because the resistance of the air gap on the spark plug increases with greater compression in the cylinder.
Changing plugs and coils solved MOST of the problem. Idle is a lot smoother but it still stalls but only after just filling the gas tank? Looks to be some sort of fuel pressure issue. Told my wife not to fill it all the way up next time and see if it still stalls.
My sister had one of these.

For some reason Dealerships don't have the info, but the web does.
IIRC, the issue is a knock sensor that gets water in the boot.
Remove boot, clean connector and it's all good - for a while.

I'll see if I can find the link in my emails...

So besides Engine Mounts (Which the Dealer changed all of them on my Sister's Jeep - they really did not want to buy it back!)

I found this, which did help.

<Quote>Cause: Moisture goes to the back of the engine. Motor wash, Oil change, Heat... (Researching the issue everyone does this and once moisture gets there never gets out. When you buy a new car guess what happens before you buy... Oil change and engine wash... If you pour the oil fast it goes out... Guess where??? Right to the socket. The electric socket pools moisture until the sensor is short. When the Camshaft Sensor sorts out the car does not know it idles.... Pretty much converts the car to an old car that had no sensors to comfort... {Model-T} The sensor also fails in higher temperatures. It is protected by a heat shield. But the sensor starts to fail over 110F... When the sensor is short the radio and other electric parts fail to function. The fuse doesn't burn. The PCM doesn't go bad. There are many Videos/articles on internet if you search the subject. Customer reviews also say 50 000Miles is the common lifetime of these sensors!!!</quote>
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