Westy661

OK so i picked up an 89 XJ on Craiglist. It didn't start but after reading on this it came down to a dirty throttle body that i got cleaned up and the plug on the CPS was dirty. It fired right up after that. However it idles around 300 and around 1800-2200 RPM it mis fires. It then runs perfect at higher RPMs. This seems to be a timing issue? I was thinking about replacing the CPS but then noticed that it might be a pain in the rear to get it out of the bell housing. Any insight on this? If i do replace it, what is the best aproach to getting in there. Seems like a knuckle buster location.

Thanks,

Westy aka XJ noob

BlueXJ

Yes it is difficult to access. Some lower the tranny crossmember and lower the tranny so that the back of the head rests against the firewall. Then it can be reached with a couple of long extensions. The trick is not to drop a bolt inside the bellhousing. Some people use a magnetic insert into the socket to help retain the bolt when it is loose. The new CPS can be notched so that you never have to remove those bolts ever again, just loosen them a little and the CPS will slip on to them.

That being said I am not convinced that you have a CPS problem. Put the Jeep in a place which can be darkened. Raise the hood and start the engine. Observe the distributor and wires while going through the RPM range and see if you observe any spark jump from wires or the cap to a ground. If you do then just replace the sparkplug wiring or cap and the problem is solved. As you can tell I am very old school. It can be said that I am so old school as to be pre-school.

jd4x426

also try pulling the spark plugs and checking them it might not be a bad idea to change the plugs wires cap rotor and coil just for a good tune up sometimes that can make a world of difference

bishop letov

definitely check the wires and plugs. If I remeber correctly it should be at 750 rpm in drive, maybe a tad lower. feel free to correct me if im wrong guys...

Westy661

Thanks for all the advise. When I got home today i took it for a drive first and it still had the problem. I did the old school/no school trick in a fully dark garage and i didn't see any sparking out, so that was good. I had a buddy at work suggest that i just go burn it down the freeway and burn off the old gas and refuel. It seems like this is more a problem with the crap they are putting in gas that attracts h2o. So good thing is that i dont have to bust my knuckles to replace that CP sensor (yet). I added fuel stabilizer and topped off the tank. It is "missing" some but not as bad. So I think tomorrow I will clean the spark plugs and really clean the throttle body and not just do a wipe down and soak it with contact cleaner.

Cheers,

Westy

zjrog

Plugs are chea[p, replace them. Is the inside of the distributor look OK or are the contacts burnt and ugly?

backfiring... SOunds very familiar, put a fuel pressure gauge on that sucker.