Intermittent SEVERE Hesitation under load

96 xj 4.0 aw4

This only happens shortly upon startup and has been progressively getting more and more frequent since february.

Most every time it will start just fine and idle just fine, but as soon as i give it throttle it will want to hesitate. once I put it under a load it gets much worse. sometimes I struggle to keep it running, othertimes I can slowly get the rpm's up to 5k and as soon as I bounce off the rev limiter once or twice it runs fine (found this out when I was pissed off).

Now it almost happens every time when cold. When hot it doesn't happen as frequent, but it does happen. The most severe times i have this issue is also when the jeep is hot. When hot it might not start for 5-10 minutes. but as soon as i get it running and bounce off the rev limiter it will be just fine.

There are no trouble codes
and every time i have the jeep on the scanner the jeep runs fine, so checking for skewed sensors and whatnot Is a little difficult.

New parts:
cat converter- month ago
catback exhaust-month ago
cps -week ago
plugs,wires,cap,rotor -month ago
fuel filter- an hour ago

before i start throwing sensors and parts at this thing i figured I would ask here for some insight.

Thanks in advance.

have you double checked that the plugs, wires, cap, rotor are all nice and snug? i had a similar issue with my dodge and it turns out that one wire was not tight to the plug and another had a faulty connector at the cap

when mine was hesitating like you describe, to the point it finally died and wouldnt start, it was the coil. i had that and the ICM tested at my local autozone. new coil in and it started right up.

stewie said:

have you double checked that the plugs, wires, cap, rotor are all nice and snug? i had a similar issue with my dodge and it turns out that one wire was not tight to the plug and another had a faulty connector at the cap

Click to expand...

all that is good to go

1990JEEPXJ said:

when mine was hesitating like you describe, to the point it finally died and wouldnt start, it was the coil. i had that and the ICM tested at my local autozone. new coil in and it started right up.

Click to expand...

i might have a spare coil lying around, its worth a shot, thanks

I'd grab a pair of MAP and MAT sensors from the junkyard and test those next

pop the distributor cap and grab the rotor and try to twist it, see if there is excess play in the dist shaft. if so pull the dist out and inspect the gear on the bottom.

I dealt with some crazy issues like that, turned out the camshaft gear was worn, and in turn was wearing off the distributor gear giving it alot of play and throwing it out of time. It was waring the teeth down to almost nothing.

Also, what about the camshaft position sensor thats in the dist? have you checked that?

check your o2 sensor.. mine did the same thing .. replaced everthing plugs wires cap coil no change .. replaced o2 sensor and all was good..