xjmuddy

i have an 88 xj 4.0 i have a definite misfire at 2000 rpm under load iv done plugs, wires, new distributor with pick up, coil, crank position sensor, new ground wires from the battery and the one on the head, also have done throttle position sensor, idle air control, and mass air flow. many of those sensors ive replaced due to other reasons but the one problem i cant seem to solve is the misfire, i replaced the o2 sensor with a bosch one it only lasted like 20 minuets until it started running bad i tested it and found it was doing nothing so i took it back and got another one i put it in tonight and it was the same story im going to get a genuine Chrysler one as soon as i can im almost convinced that the bad 02 sensors are my problem. but i would like some other advice if anyone has any. the jeep has 280000 miles its had a new motor and tranny and front and rear diffs all before i got it. any help would be greatly appreciated thanks.

cruiser54

Use the NGK 23553 sensor.

If the oxygen sensor heating circuit has a bad relay or ground, the sensor won't work correctly.

Did you index the distributor? Adjust the TPS?

What are you calling the mass air flow sensor? No such thing on your Jeep.

I suggest you go to www.cruiser54.com and perform Tips 1 through 5 before firing any more parts at your Jeep.

xjmuddy

​​​​​​i got mixed up I meant map sensor, I did index the distributor and adjusted the tps, like I said before I didn't throw all those parts at it just to solve the misfire. But thank you I'll look into heating circuit and get the better o2 sensor.

cruiser54

What method did you use to adjust the TPS?

This? http://cruiser54.com/?p=54

Indexed the dizzy like this? http://cruiser54.com/?p=68

xjmuddy

not the ways you explained there i obviously had no idea what I was talking about haha thank you a million these links? I'm not sure what there called. Are super explanatory I'm going to throw everything I thought I knew out and set it up the way you explain thank you. I'll let you know if works.

cruiser54

The site is www.cruiser54.com.

Enjoy and post up any questions you may have.