alaska_av8r

Okay a bit of background on my Jeep. I have replaced the fuel pump twice in 4 yrs, she just had a tune up of new plugs, wires and cap. Recent oil change.

While driving a few weeks ago she suddenly began to run hot and I found out the radiator was bad. I replaced the radiator with a new one and now the cooling problem is solved. However the next day the jeep started shifting very jerky. The check engine light came on and the idle is erratic to the point that it sometimes will not idle at all. The automatic transmission appears to be acting up. At a low speed when you floor it, it used to downshift into what us old farts called passing gear, you know high rpm and zoom on down the road. It will not do this now, it stays in a higher gear (maybe 2nd). Also running around 55mph it appears to shift into and out of overdrive but very jerky in doing so.

I know the transmission runs the fluid into the radiator for cooling the fluid so I am assuming that this may be what led to the problem when I installed the new radiator, but what has me confused is that it should not affect the idle.

This is one of those types of problems that has me perplexed. Am I having fuel pump problems again that is causing the shifting issue or idling issue?

Love my little red demon, but she is sick and in need of help.

thanks
tim

alaska_av8r

oops forgot to add that I took the Jeep to Oreilly's auto parts because the check engine light is on. They hooked up the code reader and it would not read the code so they said the computer was bad. Not sure if I believe them.

Bustedback

Most of the time when a PCM goes bad the engine won't run, or you will get a bunch of weird codes. I would have a trusted mechanic check it out and see whats going on, you'll save money in the long run.

alaska_av8r

The engine does run, and it runs well except for the jolting which I am not sure what is causing that, fuel or some other issue, and of course the times it won't idle but just quits.

Bustedback

have you replaced the CPS? I had a strange jerky thing going on when I hit sharp bumps. I noticed the tach needle would drop when this happened, so just for giggles I replaced the CPS and my problem was solved. I found the shifter cable on my 95GC looped back to the transmission and it has a heat shield around it. That cable and heat shield were rubbing on the CPS and moving the wires around right where they go into the CPS. I secured the shift cable away from the CPS with a few zipties and used some RTV on the new CPS around the wires where they enter the sensor to help and keep them from breaking from vibration.

alaska_av8r

I will have a look at that. I just figured it was something I may have bumped or did when I replaced the radiator. I'll do some research to learn how the cps works.