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General discussion

06 Grand Cherokee Idle issues

Dec 29, 2007 11:07PM PST

I have a 2006 Grand Cherokee Laredo 3.7L and am having idle issues. When I'm sitting at a light and the car is warmed up (driving for about 30 minutes) it will sit at 600-700 RPMs but then will drop to 300-400 for a second or two and then catch itself and rev back to 600-700. Also, when I go to take off after stopping, when it shifts from 2nd gear it will have a shudder/hard shift but shifts fine other than that.

I have repeatedly expressed my concerns at the dealership with no avail. They seem to know what the problem is when I take it in, and then they call me and say nothings wrong with it or they couldn't get it to duplicate it.

Anyone have any ideas? I've read it could be the TPS or IAC but don't know if they would replace those if I requested them too.

Discussion is locked

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They might
Jan 1, 2008 1:53AM PST

But if you request things be replaced, and that doesn't fix the problem, it will be all on you, and dealership prices are a bit high for rolling the dice on if you get my meaning.

I'd find a backyard mechanic before running that risk.

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06 Grand Cherokee Idle issues
Jan 1, 2008 7:37AM PST

Well they said they wouldn't fix it if it wasn't broken. As usaual nothing was "broken" so for now we'll see. I won't take it to a mechanic other than the dealer because my warranty is still in effect. I don't want to mess that up for when something really goes wrong.

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more info?
Jan 3, 2008 1:57AM PST

It sounds like a problem with the firing side of things, but somebody would need more info to help. I would remove, clean, inspect and reinstall/replace all of the spark plugs and wires. This will give you some power and MPGs back anyway, so do it anyway. Ensure they are gapped properly or that they are auto-gapping plugs and check the color of the ceramic near the prong(s). They should be a light tan color. If they are white or black, take it to the dealer and tell them it's running lean/rich respectively.

Here are some possibilities for the symptoms you describe. A hanes manual should show you how to check and find all the components in the car.

EGR system - will stutter when you slam on the gas, or seem to have very little power at that time or at higher speeds - may be accompanied by "check engine light"

Low, Dirty or Old tranny fluid - hard shifts or requires higher speeds/rpms to shift - could also be bad torque converter in the tranny

Failing alternator/regulator - the same as you described but may have a range of other electrical problems, such as dying battery, headlights may be dim at times, etc.

Failed RPM or speed sensor - Your speedometer may be accurate but the tranny will not shift at the right times between one set or all gears.