Frank Z
NAXJA Forum User
- Location
- Colorado Springs
1997 XJ, Sport, AW4
The motor is 4.0 (4.6L Stroker) with approximately 12k since it went in.
I’ve fighting this damn problem for a couple months and I’m completely stumped.
The problem seems rather common, stumbling, hesitation, buck/lurch at speed or from a standing start.
From a standing start and accelerating normally the jeep wants to die, it stumbles really bad and has died on occasion. Restart takes a bit of cranking with the pedal mashed to the floor.
At about 50 mph it will buck and lurch until I mash the gas and get the RPM’s up to about 3k. Generally this starts at about 2k to 2.5K RPM’s.
So here’s a list of the parts that have been replaced after searching here and elsewhere for a solution to this problem. Note that all of these are new within the last 3-6 months.
Fuel pump assy. (today)
Fuel pump (only)
TPS
CPS (crank)
CPS (cam)
IAC valve
Distributor
Cap and rotor
A few of the measurements, if it helps:
5VDC into the Crank sensor
5VDC into the Cam sensor
13.6VDC at the fuel pump connector
Fuel pressure before new pump assy. was 39 PSI, after the new pump went in it went to an amazing 40.5 PSI. I thought that the 97-01 fuel systems were supposed to be at 49 PSI?
The idle is not steady. It fluctuates between approximately 650-850 RPM.
I’ve even gone as far as replacing the transmission. Yeah I know it sounds nuts but some of the symptoms pointed to faulty shift solenoids and I got the tranny for a great price (Thanks Yellaheep!!).
OBDII reports a “43” Cylinder 3 Misfire, but today is the first time it’s ever come up.
So what am I missing?
The motor is 4.0 (4.6L Stroker) with approximately 12k since it went in.
I’ve fighting this damn problem for a couple months and I’m completely stumped.
The problem seems rather common, stumbling, hesitation, buck/lurch at speed or from a standing start.
From a standing start and accelerating normally the jeep wants to die, it stumbles really bad and has died on occasion. Restart takes a bit of cranking with the pedal mashed to the floor.
At about 50 mph it will buck and lurch until I mash the gas and get the RPM’s up to about 3k. Generally this starts at about 2k to 2.5K RPM’s.
So here’s a list of the parts that have been replaced after searching here and elsewhere for a solution to this problem. Note that all of these are new within the last 3-6 months.
Fuel pump assy. (today)
Fuel pump (only)
TPS
CPS (crank)
CPS (cam)
IAC valve
Distributor
Cap and rotor
A few of the measurements, if it helps:
5VDC into the Crank sensor
5VDC into the Cam sensor
13.6VDC at the fuel pump connector
Fuel pressure before new pump assy. was 39 PSI, after the new pump went in it went to an amazing 40.5 PSI. I thought that the 97-01 fuel systems were supposed to be at 49 PSI?
The idle is not steady. It fluctuates between approximately 650-850 RPM.
I’ve even gone as far as replacing the transmission. Yeah I know it sounds nuts but some of the symptoms pointed to faulty shift solenoids and I got the tranny for a great price (Thanks Yellaheep!!).
OBDII reports a “43” Cylinder 3 Misfire, but today is the first time it’s ever come up.
So what am I missing?