Crazy idle situation

Hello all,

I am new here, but have owned 3 XJ's. Great vehicles, and loved all of them.

My 1995 sport is having a problem that I can't figure out, and I need some advice.

The Jeep idle's very rough (although not all the time sometimes its totally smooth)

Here is a list of whats been done.

1. cap, rotor, plugs, wires
2. throttle body removed and cleaned.
3. new fuel injector, checked all, only one was bad.
3. new idle air control sensor ( on the throttle body)
4. vacuum lines checked for cracks ( replaced where necessary)
5. compression test. 110 on 5 cyls and 85 on the #1 cyl ( typical for 190,000 mile jeep)
6. New 02 sensor.
7. endless bottles of chevron techtron LOL

I am when it is idling rough, i noticed that it smells very rich ( like fuel) I am really wondering if the PCM is malfunctioning. Sometimes the car wont start unless I feather the gas pedal.

The neutral safety switch is bad, but when it malfunctions, I just but the car in neutral and it starts right up. Could this be affecting the idle? I don't really think so.

Thanks for any/ all help,

Trevor

Hello,

Am I the only one with a intermittent rough idle problem? Does anyone know anything about this?

Thank you,
Trevor

Hallo. Maybe. Maybe you can check the sensors of the air temp and the coolant temp. (MAT and CTS) . The engine can run too rich after warming up.
It is not a lot of work and not expensive to do. :wave:


'92 XJ

You have answered your own question: 85 psi cylinder is too weak. All cylinders should be within 10% of the others, your number 1 is 22.8 %.

Hey Joe,

If you pull the wire on that cylinder it still runs rough...... When its actually running rough. lol

I dunno, normally I would agree regarding the compression, but I'm not sure on this one, there are to many other anomalies. The fuel smell, and having to give the car gas sometimes when it's cold being two of them.

These engines aren't too picky with the internal balances, in fact i've seen them run with some crazy tolerances out of whack.

Trevor

cuda75 said:

Hey Joe,

If you pull the wire on that cylinder it still runs rough...... When its actually running rough. lol

I dunno, normally I would agree regarding the compression, but I'm not sure on this one, there are to many other anomalies. The fuel smell, and having to give the car gas sometimes when it's cold being two of them.

These engines aren't too picky with the internal balances, in fact i've seen them run with some crazy tolerances out of whack.

Trevor

Click to expand...

Do a wet compression test on number 1 and see what happens. If it comes up then its rings, if it doesn't its valves.

I think you are right Joe.....a wet compression test is in order.

Trevor