I just picked up an 88 xj with the 4.0 when it warms up it starts missing real bad dose not want to accelerate but if you put your foot to the floor after about 3500 it acts like it clears out and put all the way to 5000. just run like crap when you try to cruise. this is my first jeep and I know nothing about them any ideas where I should start looking? any help would be appreciated

 

Start with a good tune-up: Spark plugs, wires, oil, filter, fuel filter, air filter, maybe even run some seafoam through the oil and next fill-up through the fuel system. might wanna replace your fuel injectors too, just to be sure it's runnin good.

 

so i did a tune up and changed the iac valve and coil and module and still the same. runs perfect when cold only having the problem after warm up. any other ideas?

 

no idea, mine sounds like its missing a little if u let it idle, maby a sensor or something.

 

My '88 did something like what you are describing and it turned out to be a combination of a vacuum leak to the MAP sensor and an out of adjustment TPS motor (sensor). Try checking everything first before you start throwing parts that you don't need at that XJ!

 

at idle it is a little miss but when you try and drive it it starts to miss real bad then backfires and pops out the exhaust.

 

how do i check the tps adjustment?

 

just check tps in spec. it is also backfireing thru the intake would that be timing related?

 

also make sure the pick-up in the distributor isn't broken off,thats what happened to mine.

 

ok thanks will take a look

 

Google "another freakin jeep cherokee website" You will find specs and how to's for all your sensors.