Chrysler Repair: 97 Grand Cherokee 4.0L Multiple Missfire, jeep grand cherokee, tps sensor

Question
Hi Kevin
We have two 97 4.0L Jeep Grand Cherokee's One is golden and the other is like a bad stepchild. Of course the one wit hthe loweer miles is givign al lthe ptoblems. We have replaced plugs, wires, Coil, TPS sensor, cleaned the throttle body but thr problem just keeps coming back. It happens in the morning and only for a few seconds but is enough to turn the Engine light on and the code always reads multiple missfire with no difinitive direction. Does your Exhaust valve rotation TSB issue apply to 97's? THis truch has 11kK while the golden child has 140K with no problems. Any help you can give woudl be greatly appreciated as I'm tired of feedign the dealerships pockets with no resolution.
Thanks
Aaron A.
Bugord Georgia

Answer
NO: 18-14-97 Rev. A
SUBJECT: Rough Running Engine with Hex Codes $28, $6A, $9B, or $BA
DATE: May 9, 1997
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 18-14-97, DATED APR. 4, 1997, WHICH SHOULD BE REMOVED FROM YOUR FILES. ALL REVISIONS ARE HIGHLIGHTED WITH **ASTERISKS** AND INCLUDE MODEL YEAR CHANGES FOR ZJ MODELS.

NOTE:THIS BULLETIN APPLIES TO VEHICLES WITH A 4.0L ENGINE AND AUTOMATIC TRANSMISSION.

SYMPTOM/CONDITION:
MIL illumination with the potential for a rough running engine between 2500 to 3000 RPM. The MIL may be illuminated due to one of the following DTCs:

Hex $28 - NO CRANK REFERENCE SIGNAL AT PCM
Hex $6A - MULTIPLE CYLINDER MISFIRE
Hex $9D - INTERMITTENT LOSS OF CMP OR CKP
Hex $BA - MISFIRE ADAPTIVE NUMERATOR AT LIMIT
DIAGNOSIS:
Using the Mopar Diagnostic System (MDS) or the Diagnostic Scan Tool (DRB III) with the appropriate Diagnostic Procedures Manual, verify all engine systems are functioning as designed. If Diagnostic Trouble Codes (DTC's) other than those listed are present, record them on the repair order and repair as necessary before proceeding further with this bulletin.

Run the engine while monitoring the vehicle crank position signal. Slowly increase and decrease the vehicle engine rpm to determine if the vehicle crank position sensor signal is being lost. If no DTC's other than those listed above are present and the vehicle crank position signal is lost, perform the Repair Procedure.

PARTS REQUIRED:
Quantity
Part No. Description
1 04897321AA Sensor, Crank Position (adjustable)
1 05252229 Spacer (only required for sensor R&I)
2 04641780 Tie strap
1 CH6000 Scan Tool (DRB III )
1 CH7035 General Purpose Interface Bus Cable (GPIB)
1 CH7000/7001 J1962 Cable



REPAIR PROCEDURE:

This bulletin involves replacing the crank position sensor with a new part to allow adjustment closer to the engine flywheel.

Remove the crank position sensor from the transmission bellhousing and discard the non adjustable sensor.
Install the new sensor p/n 04897321AA into the transmission bellhousing hole.
Rest the sensor against the flywheel/drive plate. With the sensor contacting the flywheel/drive plate, tighten the attaching bolt to 7 Nm (60 in-lbs).
NOTE:IF THIS SENSOR IS REMOVED DUE TO OTHER SERVICE PROCEDURES, IT MUST BE PROPERLY REINSTALLED WITH A NEW CARDBOARD SPACER P/N 05252229.

Secure the sensor connector and wire using two plastic ties p/n 04641780. Position one tie to each side of the connector as applicable (Figure 1).
NOTE:THE CRANK POSITION SENSOR CONNECTOR MUST BE SECURED TO PREVENT EXCESSIVE MOVEMENT AND POSSIBLE WIRE FATIGUE