Hey everyone. im new to the jeep game. just bought a 2001 xj with a 4.0L.. i just came across a problem and just want to see what everyone thinks.. maybe a sensor or worse.... ill try to explain... i can get in the truck and drive it fine.. runs good.. off the start i notice high oil pressure and as the truck warms up oil pressure goes down to about "normal". heres my problem.. if i stop to fuel up or get some food or something. i get back in the truck go to start it and it either wont stay running... idle drops down and sounds rough with no power. or has a low idle with a loud knock that goes away. if i press the gas pedal there is no power. after a few seconds of holding the pedal down the idle averages out and everything is fine.. im leaning towards either plugs and wires, injectors, fuel filter, or a sensor.... truck has 173,000 on it and otherwise runs great. any help would be great. i would like to resolve this issue. Thanks!

 

anyone have any ideas???

 

Brandon, with a 2001 there are no plug wires. But you absolutely should start with fresh spark plugs. For the 00-01 with the distributerless ignition, I recommend NGK copper plugs. Be sure they are properly gapped to .035 before installing; never assume gap is correct out of the box.

Do you ever see a check engine light? Even if the answer is no, you may want to have the computer scanned to see if you have any stored or pending codes.

What oil pressure numbers are you seeing? The spec for the 4.0 is not less than 13 psi at HOT idle and between 37-75 over 1600 rpms.

Have you heard about the 0331 head problem? Not trying to scare you, but you absolutely must educate yourself about it if your engine still has the factory head. Read this thread and be sure you watch the coolant reservoir like a hawk as the #1 symptom of a cracked 0331 head is unexplained coolant loss.

http://www.jeepsunlimited.com/forums...d.php?t=391831

 

You may also be experiencing heat soak episode. It may or may not trigger a misfire code (usually on cylinder 3).
Do a search and there is a great deal of info on that too.

 

No fuel filter to replace on a 2001 without removing the fuel tank. It sounds like a heat soak issue.

 

I don't want to hijack this thread but this may help the OP too.

Would a CARFAX state if the head has been replaced in the vehicles lifetime if the dealer or another shop replaced it, or does it only show collision repair?