thejeepgod
NAXJA Forum User
- Location
- CO
Backstory: 99 XJ has a stumble on acceleration, usually at lower speeds. It only happens when it is cold, i.e. first pulling out of the driveway in the morning, or when the jeep has sat for a few hours. This usually happens in the 1500-3000 rpm range, it does not last very long (few seconds) then it will recover and return to a normal power level. It never feels like its about to stall, its just a hesitation. It will usually only do this once during the course of driving, and runs normally otherwise. The check engine light is not on.
I have access to many parts jeeps, so I have been swapping things over in an attempt to fix this, so far I have changed out the following with new or known to be good units and it still does the same thing:
fuel pump
fuel rail w/ injectors
throttle body w/ all attached sensors (MAP, TPS etc)
Distributor Cap/Rotor/Plug Wires
Hall Effect Sensor aka camshaft sensor
Crank Position Sensor
Pre-Cat Oxygen Sensor
Spark Plugs
ECU - this did help for a while, but then it seemed to re-learn things and it came back.
I have also done a visual inspection for vacuum leaks and broken grounds, did not find anything.
Now I'm stumped, I've changed out nearly every sensor on the engine...anyone else have any ideas on what this could be??
I have access to many parts jeeps, so I have been swapping things over in an attempt to fix this, so far I have changed out the following with new or known to be good units and it still does the same thing:
fuel pump
fuel rail w/ injectors
throttle body w/ all attached sensors (MAP, TPS etc)
Distributor Cap/Rotor/Plug Wires
Hall Effect Sensor aka camshaft sensor
Crank Position Sensor
Pre-Cat Oxygen Sensor
Spark Plugs
ECU - this did help for a while, but then it seemed to re-learn things and it came back.
I have also done a visual inspection for vacuum leaks and broken grounds, did not find anything.
Now I'm stumped, I've changed out nearly every sensor on the engine...anyone else have any ideas on what this could be??