96 cherokee sputtering backfire

[jgillis]

OK its a 96 cherokee 4.0

I'v had this problem for quite awhile it will start pretty good and drive good until it got up close to operating temp then would sputter and pop like backfiring through the TB.I have replaced tps,plugs wires dist cap, rotor and O2's.The key codes would allways be O2 sensor and missfires.After alot of reading here and other fourms I looked to the IAC,cleaned it no luck.I probable damaged it because i worked the plunger in and out without knowing that was a bad idea(lol).I swaped it out with one i had from an older vehicle, still the same.So i just disconnected it, now it starts bad and i have to let it warm up good then it runs fine all day.So im asumming i need a new one does this sound right to you guys?
I'll let ya know if it works but it will be a week before i can get oneÍ live in the sticks lol.

[fredjacksonsan]

How many miles? When it sputters, does it run rough or cut out entirely? With the 4.0 and more than 90K miles, I'd suspect the CPS (Crankshaft Position Sensor) of possibly being involved.

[jgillis]

The cherokee has 160,000k,I was thinking about the cps but when i was at the jeep dealer they didn't have one in stock and the guy told me they rarely fail he didn't have a record of ever selling one on file!
It doesn't cut out it run rough and backfires i also get an exhaust smell when it happens.

[fredjacksonsan]

Never sold one? Pulling your leg I think. The cps can be had at local parts stores, and are usually a little cheaper.

[dave92cherokee]

Originally Posted by fredjacksonsan

Never sold one? Pulling your leg I think. The cps can be had at local parts stores, and are usually a little cheaper.

^that's probably why they don't have a record of ever selling one because they charge way to much for everything. The guy at the parts counter probably works at a jeep dealership and drives a chevy so doesn't really know the frequent problems with the cps's.

[jgillis]

LOL

The one thing that bugs me is the temp thing ít will never act up until the temp gets to just before normal and then after a couple of miles kicking it down it goes away.When i stop for a few bit then start up then it acts up again same thing.

[AlohaBra]

Maybe a plugged cat? Fuel injection coolant temp sensor?

[ShakerZ]

I just started having the exact same problem with my 1992 straight six, im going crazy trying to figure out the problem. So far ive replaced: Wires, plugs, ignition, rotor, cap, the whole throttle body and both sensors. Please, HELP!!!!!

[purplandgold]

Ok. I feel your pain on this issue. I had been having the exact same problem with my '96 Cherokee 4.0L. I did all the usual ignition tune up replacements including both of the oxygen sensors. Nothing I tried was fixing the problem.

I finally said enough is enough and decided to dig into the wiring harnesses and connections in order to at least cross that off the list of possibles and low and behold, after opening up the wire loom and inspecting the wires that connect to the DOWNSTREAM Oxygen Sensor I found a small area where the insulation had worn and it was frayed. I spliced in the section using a couple inches of 16 guage primary wire and two butt connectors and I havent had any problems since. Also, as a by-product, my gas mileage has increased also.

So I guess my old man was right after all - When all else fails, check every FREAKING wiring connection that might be involved.