2001 Jeep Cherokee very bumpy initial idle

jeep
cherokee

#1

Hi all,

I have a 2001 Jeep Cherokee Sport edition, automatic transmission, about 100k miles. Recently, when I turn on the engine – sometimes – it is very loud, and the car really shakes back and forth (in place) with the engine. It almost feels like the car is going to die. It feels like a very bad idle. If I wait, nothing changes. If I turn the car off, wait, and turn it back on, nothing changes. If I hit the gas, it continues, but decreases very quickly and by the time I hit a stop sign or red light (let’s say 100 yards away), the car is more or less fine; no more fear that it’s going to die, although there’s still some noise that seems like it’s coming from somewhere between the transmission and engine. I had the starter replaced last June (when it went kaput) and replaced the idle control valve a couple of months ago (the car kept dying when I came to a complete stop). Does anyone have any idea what’s going on now?

Thanks for any help!
Charles

PS As an add-on to car info, we drove from NJ to CA this summer, and are currently living in CA. I mainly drive it to/from work, about 50 miles each way, going 45-80 mph on a hilly freeway, and there have been no problems while driving.


#2

Lots of things can cause idle problems. So this is like throwing darts blindfolded.

  • Is the check engine light on?

  • It’s always best to check over very basic maintenance items. How old are the spark plugs & wires? (Although I think this is coil on plug so it doesn’t really have wires). Fuel filter? Putting a fuel pressure gauge on it from a cold start would be a good idea.

  • A faulty coolant temperature sensor can result in a bad fuel mixture on cold start-up resulting in running either too rich or too lean.

  • Maybe you can describe the noise that you say persists after you’ve driven a bit and the idle smooths out.


#3

I seem to recall that the Jeep 4.0 straight six was known for cracked cylinder heads