So i bought a jeep that has an misfire issue. They have replaced most of the electronics on it a well as the computer and now they replaced the crankshaft sensor but to my knowledge that hasn't fixed it. Now this shop said he would have it running before i could have it but our deal was that since i bought it he will fix it up so it runs because he wouldn't want o sell me a faulty jeep. With that being said I'm just curious what it could be in y'all's opinions. Thanks ahead of time for everyone's word

 

Also let me state its an 2001 jeep cherokee xj 4.0 lol just fir refrence

 

The only way to "fix" a misfire is by process of elimination. If its a single cylinder misfire, you can move the injector and see if the misfire moves. If it doesn't, then you need to rule out cylinder compression by doing a compression test.... You get the picture..

 

There's probably Diagnostic Trouble Codes associated with the missfires. See if the shop has pulled any codes with a scanner or code reader. If so, get the codes and post them here - the code numbers, not what has been interpreted as to what the code(s) mean.

 

Why don't you update your profile to show what XJ you have and what equipment is installed. Open the "User CP" in the top banner of the forum and open "Edit Your Details" from the dropdown list to enter your data.

 

2001 XJ misfire?

Cracked head is a strong possibility. Search for "0331 head".

 

Before you get to involved check the spark plugs. I had a random misfire awhile back and one of my plugs was not set to the right gap.

 

CCken i cant because i use this app on my phone and it doesnt give me that option or i just cant find it

 

Checking the injector is a good idea.

Checking the spark plugs also is good idea.

If it's P0300 (random misfires), check the coil pack (I forgot the proper procedure to check it) and visually inspect the wiring harness that powers the injectors and the sensors on the TB. (Above the intake manifold and along the fuel rail).

Heck, just check the wiring even if one cylinder is misfiring, in addition to checking the injectors.

 

I had/have the same issue. I too just purchased an xj, its a '97. Anyway after checking fuel and ignition the shop determined it was a leaking valve causing the misfire. They want to do a top end rebuild but i decided to hold off until i can gather the funds. Hopes this helps any.