I have a 1989 Jeep Cherokee 4.0 fuel injected that is running horribly. I can start it and rev it up and it does fine never misses a beat but as soon as i get going bout 35-45mph it starts skipping really bad. Had it almost choke out twice today. Had the problem bout a week so I replaced the plugs yesterday thinking that was the issue. Ran better and started easier but same problem. This is when things seem to have got worse. Wires look pretty new so dont think its them but idk. Any and all help would be great its got me puzzled its weird it only does it while its in gear like I said even in park I can rev it up and hold the revs up there and it never does it what am I missing?

 

One of two things i would say

Tps or CPS. I would
Start with CPS die to that fixing mine

 

i had the EXACT same problem in my baby and it was the crank positioning sensor or (CPS).

to test.....
1)unplug your cps connector
2)set your voltmeter to read AC volts and probe the cps side of the connector
3) have someone crank over the motor (will not start with cps disconnected.)
4) while the motor is cranking, check the voltmeter and it should read between .5-.8 volts AC.

if your cps does not read at least .5 volts AC it has gone bad or if you have a manual transmission you may have old clutch material over the magnet of your cps. if it is not reading proper voltage try removing the cps and cleaning it off and re-install it and see if that helps.

 

x2

 

Ok so went to check my cps and found the wire was right on the exhaust so its just bought burnt through. Looks like thats what it was from what I can tell. Now just gotta find time to get the new part and put it on I'll keep yall updated bout it after i replace the sensor as to if that fixes it or not. Thanx guys huge help now I know where to turn with all my questions that are sure to come.

 

your better off just fixing the wires, but if ur gonna buy a new sensor buy it from the dealership because the autoparts stores sensors don't put out enough voltage and will cause you to have the same problem you're having. So just buy it from the dealership.

 

Wow thats crazy woulda thought it would have been an oem equivalent. Think ill just fix the wires then and it saves me like $40 just fixing it. Ill try to do it this weekend. Again thanx yall

 

Good news I fixed my CPS last weekend and I havent had any issues with it skipping.

 

Glad to be of service, did u get a new one or fix the wires?

 

End up just fixing the wires and had to put a new battery in it as well but all is good now. again thanx guys.