I have a 98 xj with the 4.0.

It was running really rough and would stall at low speeds. The code reader said cylinder 1 misfire, injector. We replaced all 6 injectors with Bosch 4 hole injectors. We also replaced the fuel pump and entire sending unit/module.

After these fixes, nothing changed. Put on a new cap, rotor, wires, plugs, and a throttle position sensor. IAC and MAP appear to be working and have been replaced within the past 1-2 years. Still having issues.

Intermittently, the engine backfires through the air box. Weird thing is, when pulling injectors, 1,2, and 3 there is no change to the idle. When pulling 4,5, and 6, the engine chokes. The engine sounds almost normal until it starts backfiring, otherwise it’s still choking. I am out of ideas and hopefully can get some help here. Thanks.

 

Take a top down pic of your distributor and where your wires are going.

 

Should be like this:

 

Have you done a compression test ? and checked to see if you broke a valve spring or may be a flat cam ?

 

The wires match the diagram above. We have not checked compression, valve springs, or for a flat cam.
We also replaced the CPS. A year ago, we did the Head, head gasket, lifters, pushrods, pistons etc. Haven’t had any problems engine wise since then, until now. No codes are being thrown currently either.

 

The distributor could have moved from where it needs to be