Afternoon, I recently did a rebuild on my 4.0, after reassembly I find the back 3 cylinders are misfiring. I get new plugs, doesn't fix it, get a new coil pack rail, doesn't fit it, get new Injectors still doesn't fix it. I swapped an I ejector plug with one that wasnt firing and it seems the back 3 injector harness plugs are not working. I need some help with what I can do to fix it. Thank you.

 

Not sure what year XJ you have but they sell pigtail plug ends you can splice in to replace them

Like these.

https://www.ebay.com/itm/6PCS-EV6-EV...e/173895312971

 

I went to a junk yard and pulled 4 harness plugs I spliced them in and I'm still not gettinganything. .

 

And it's an 01 sorry

 

Pull your injector plug end off one by one to test you plug harness wires. If you have a multi meter, ground the neg lead to the neg battery terminal. While the engine is running, test you plugs hot wire. You should get 0 on one wire and 13.9 on the other. 1 by 1 test each one. The plug ends you got from the junk yard may also be bad. It's a common problem with the injector wires as they are subjected to extreme heat over years of use.

 

Okay thank you I will try that.

 

possibly have the injector plugs on the wrong cylinders.

 

Ok so I have found the back 3 cylinders arnt getting power to the Injector plugs. I wired them to the front 3. All 6 fire now but it sputters a little. I need some help trying to find a correct fix. Thank you.

 

Welcome to the forum, Darth Maul. On this problem, you say you rebuilt the engine. Taking this at face value, might I ask what this rebuild entailed, and what parts of it you did yourself? Just curious. And, you are familiar with the 01 cracked head problem, right?

 

I replaced the pistons I didnt have the proper tools or equipment to do crank bearings, cam bearings, I didnt want to mess with the timing gears but I have a new set all I did was gaskets from top to bottom new pistons and rings.

 

And, you are familiar with the 01 cracked head problem, right?

 

I am, when I pulled the head I inspected it, I didnt see any cracks.