Spark plugs covered in soot and oil. Just replaced less than 50 miles ago. Starts fine when cold. Dies when it's put in gear. Won't restart after it's hot. What's inside my engine that shouldn't be?

 

Coolant temp sensor could be telling PCM the engine is cold.
Is the check engine lamp on?
Cold be a trouble code to guide your diagnosis

 

X2 sounds like it is running rich, A scan tool can tell you what the temp sensor is reading. My dad had this problem, his temp sensor read -48* all the time.....This told the PCM to dump fuel....all the time.

 

X3, check the function of the CTS.

 

Just out of curiousity, what plugs are you running?

 

Autolite platinums

 

It could be CTS I haven't been paying attention to the temp Gauge since it won't run long enough to get hot

 

The CTS and water temp sender are two different things. One (CTS) is for the ECM to read the coolant temp, and the other is only for the gauge. Have you check the coolant level lately?

 

The advantage of platinum plugs is longevity not performance. Platinum plugs tend to foul quicker than copper core plugs. OEM plugs are Champion RC12ECC I believe.
Not that this will cure your problem, just for your information.

 

This is true on the older XJ's, But '97 and up use one ECT sensor. The PCM then sends the temp signal to the Instrument cluster over the vehicles network(CCD BUS).

 

having problems again. Ive replaced damn near everything on this jeep. new crank pos sensor, throttle pos sensor, CTS, pulled a head from the junkyard, took it apart, cleaned it up, polished the combustion chambers a little bit, ported it, new head gasket, intake/exhaust gasket, valve cover gasket. head is sealed great, all cyl at 130+ psi. did the Neon 703 injector swap with new O-Rings, spark plugs, wires, cap, and rotor button.

CTS seemed to work great this weekend but today had starter problems. jumped the starter and that worked a couple times but besides that after i jumpered the starter it was doing the same thing, wanting to die when i come to a stop. its like it just doesnt want to run right. im gonna put another new set of plugs in it tomorrow and drive it and see what they look like. I really dont see any mechanical problems causing this since its basically a brand new engine. I'm starting to think this jeep has some major electrical problems. turn signals dont work (never have since ive owned it), when i try to turn on my hazard lights my part time light comes on and i hear a buzzing sound (hazards wont work either), now the starter issue. I guess my real question is could electrical problems be causing this sort of problem? everytime i replace something it seems to work for a few days and then starts running terribly again.

 

Good to know, thanks.