Most of what I could find was either Renix, or the OP never came back and filled us in on what the issue was...

94 XJ 4.0 AX-15 172k on clock.

New exhaust...new cat and muffler, new O2 sensor, new TPS, cleaned the IAC, cleaned the entire TB. Tune up is 6 months old. New KPS, swapped out the distributor 6 months ago with a used. Fuel is good, and running freshly cleaned 703 injectors installed 5 months ago.

I am missing. Something bad at times, and gets worse as the Jeep warms up. I have also been noticing a rotary grinding noise, more like a high pitched metal on metal type noise that seems RMP dependent. NO CODES, NO CEL...reset ECM 1 week ago after replacing the O2 to clear codes and see if any new ones come back...notta.

Think it might be the distributor gears causing the miss AND the noise? Would I hear that?

Help...I want my power back....

Thanks!

 

Is the noise coming from the rear of the engine? You might have a broken flexplate.

 

I'm going to point my finger at the distributor as the most likely culprit in this scenario. Mainly because it was used and has the potential for causing both the miss and the noise.

If you still have your old one and it was working consider swapping back to rule it out.

 

Obviously arbitrarily throwing parts at it didn't help

Try diagnosing it.

codes?

Brand of plugs?

Compression test?

Manifold smoke test?

Where is the noise coming from? Use your ears.

At all speeds, idle, mid range?

We can't help unless you do part of it!

 

Ended up being a few different problems at once confusing me.

Let's say this...I will not buy Bosch +2 plugs again. They were fried after 6 months...causing the miss. Not dirty, the electrodes were fried. The distributor was fine. I went back to Champion copper core.

The grinding sound it turns out, is the bearings of the alternator going bad. I oiled them, and they are fine for now.

Jeep is running well so far.