Does My XJ Run RIght?

92 xj 4wd 5spd. less than 12k miles on Mopar Remanufactured long block.

Runs fine, I guess, few less mpg than my old motor with 220k miles on it did.

Thing is, when I accelerate hard, onramp or similar situation, its a tiny bit rough until 3-3500 rpm, then it smooths right out and really pulls strong and smooth.

Is this normal? HAs been this way since I put motor in.

Bigjfb said:

92 xj 4wd 5spd. less than 12k miles on Mopar Remanufactured long block.

Runs fine, I guess, few less mpg than my old motor with 220k miles on it did.

Thing is, when I accelerate hard, onramp or similar situation, its a tiny bit rough until 3-3500 rpm, then it smooths right out and really pulls strong and smooth.

Is this normal? HAs been this way since I put motor in.

Click to expand...

dead spots on the TPS? mine had rough spots around 50-60 and it turned out to be a simple TPS failure.

Seems like you would have fuel delivery issues on the top end if it was a fuel pump/injector issue, rather than the bottom end (e.g. smooth until the output of the pump/injectors was reached, and THEN it would cut out.)

spark/coil/plugs would miss at all speeds, if they were bad, right?

hmmm. I'll put my thinking cap on.

SanDiegoOverland said:

dead spots on the TPS? mine had rough spots around 50-60 and it turned out to be a simple TPS failure.

Seems like you would have fuel delivery issues on the top end if it was a fuel pump/injector issue, rather than the bottom end (e.g. smooth until the output of the pump/injectors was reached, and THEN it would cut out.)

spark/coil/plugs would miss at all speeds, if they were bad, right?

hmmm. I'll put my thinking cap on.

Click to expand...

I would expect the coil/wires/plugs to screw up more at higher RPMs.

Agree, test the TPS with an analog meter through its full range of travel.