I have a 1995 XJ 4.0 HO auto 2wd. Rebuilt head, timing chan set complete tune up and still has a rough idle. The timing at an idle will fall off about 8 degrees intermittently when it stumbles and has a slight movement at 2500 rpm. Has anyone had a similar problem and what was the solution. Is there a knock sensor on my engine I cant find one. The timing advances steady with the throttle but goes back to jumping at an idle. The book says the crank sensor is for the timing and the cam sensor is for the injector pulse width could it be either the cam or crank sensor.

 

Sounds like a crank sensor problem to me. They CAN have intermittent problems. 1990 was last year of Knock sensor on 4.0s.

 

Has anyone else had this problem and what was your solution thanks.

 

Ok recap rebuilt head, timing set, TPS, IAC, 0-2, MAP, CPS, plugs and wires cap rotor still had the same miss. I took a screwdriver handle and tapped on the throttle body and it studdered. Went to the bone yard and got a TPS connector and she purrs like a kitten lots of power. I was trying to get it running good enough to sell now I dont want to get rid of it I even washed it today. Oh well next project mercury 30hp mark 30 outboard.