Renix help needed

OK here's the issue my daughters '89 XJ started a odd little prob..

When cold runs great..

When warm, it will not rev over 3500RPM and back fires and has no power. When this happens if you sit in Neutral with your foot on the gas it revs up to 3500 than to zero over and over..

It's running super RICH, black exhaust smoke..


I have changed:

TPS, IAC, MAP, MAT, Pick up Coil, ECU, Engine Temp Sensor..

I also replaced the ECU

Any ideas?

I've searched and search and just can't seem to find something that helps... 12 solid hours working on it yesterday and still not sure..

02 sensor?

Replaced it also...

Only 2 things I have not replaced or messed with are the EGR and the CPS...

Have you checked the hose to your MAP sensor? If it is cracked, melted, or not plugged into the throttle body properly, it will run pig rich.
Did you adjust the new TPS after installing it?

Jeep is FIXED..

Turns out that the Fuel pump I installed (used) was droppen off pressure the longer it ran..

Glad you got it fixed, but low fuel pressure/volume should make it lean, not rich.

I also had 5 Vac. leaks, and bad CPS...

Nick_n_ii said:

I also had 5 Vac. leaks, and bad CPS...

Click to expand...

Now that makes sense!! Low vacuum to the MAP will cause it to run real rich. Glad you got it fixed.