1998 Jeep Cherokee Engine Missing

Tiny
BARRA
  • MEMBER
  • 1998 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 73,000 MILES
Hello,
my Jeep Cherokee Sport engine is missing and idling very rough on start up. It still performs well, I'm just wondering what might be causing the problem.

Any assistance would be very much appreciated,
regards,

Barry
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Tuesday, August 5th, 2008 AT 6:59 PM

3 Replies

Tiny
SERVICE WRITER
  • EXPERT
Hey Barry,

Is the CEL lit up?
IF so post the codes that it has. IT would be good to know what cylinders are missing to diagnose.

I have run into a fair amount of 4.0 motors that seem to be problematic with the injectors plugging up. A fuel inection cleaning professionally done should be done every 30,000 on these motors.

But let's start with codes.
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Wednesday, August 6th, 2008 AT 5:18 AM
Tiny
BARRA
  • MEMBER
Hello, sorry for the slow response, and thanks for the reply.
To date, I am still driving the car, the CEL does not light up, yet I have been told, after a diagnostic check of the motor, I have a bad valve which requires the replacement or reconditioning of the head.
There is definitely a miss happening, and it runs rough on start up, yet still goes quite well once moving.
I'm a bit puzzled as to my next move, so any further information would be most welcome.
Am very surprised this should happen on such low mileage, yet having been a Jeep owner for about 8 years, I'm getting used to the odd difference happening.
Not too pleased with this one though.I haven't had the injectors done, should this be my next move?
Appreciate the help,
cheers,
Barry.
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Sunday, August 24th, 2008 AT 10:39 AM
Tiny
MERLIN2021
  • EXPERT
This may be the problem then:
OBDII MISFIRE MONITOR - CODE & DIAGNOSIS TECHNICAL SERVICE BULLETIN Reference Number(s): 18-22-98, 18-31-97, Date of Issue: June 12, 1998 Superceded Bulletin(s): 18-31-97, Date of Issue: January 30, 1998 Related Ref Number(s): 18-22-98, 18-31-97 ARTICLE BEGINNING OBD II MISFIRE MONITOR Model(s): 1997-98 Jeep (TJ) Wrangler 1996-98 Jeep (XJ) Cherokee 1996-98 Jeep (ZJ) Grand Cherokee Group: Vehicle Performance Bulletin No: 18-22-98 Date: June 12, 1998 SYMPTOM/CONDITION Malfunction Indicator Lamp (MIL) illuminated with either a Multiple Misfire or individual Cylinder (1-6) Misfire Diagnostic Trouble Code (DTC) recorded in the Powertrain Control Module's (PCM) memory. The MIL illumination may be accompanied by engine vibration. DIAGNOSIS Refer to the 1998 2.5L/4.0L/5.2L/5.9L SFI Jeep Powertrain Diagnostic Procedures Manual (Publication No. 81-699-97019), test TC-106A for the Multiple Cylinder Misfire DTC or test TC- 107A for the Cylinder #(1-6) Misfire DTC. For any future reference, record and document Freeze Frame data. NOTE: This bulletin supersedes Technical Service Bulletin 18-31-97, with effective date of January 30, 1998 which should be removed from your files and noted in the 1997 Technical Service Bulletin Manual (Publication No. 81-699-98004). The Decarbonizing Procedure has been revised along with the Labor Operation Time Allowance. NOTE: This bulletin applies to vehicles equipped with the 4.0L engine. NOTE: Both test TC-106A and TC-107A are revised with Technical Service Bulletin 26-12-97 released December 1997. DO NOT use the procedure Page 1 of 3 OBDII MISFIRE MONITOR - CODE & DIAGNOSIS -1998 Jeep Cherokee Limited 8/24/2008
Perform the repair procedure identified in the Powertrain Diagnostic Procedures Manual unless your diagnosis identifies that an engine mechanical problem could be causing the OBD II Misfire DTC. If the Powertrain Diagnostic Procedures Manual identifies a possible engine mechanical problem, perform the Repair Procedure. PARTS INFORMATION PARTS INFORMATION REPAIR PROCEDURE This bulletin involves installing revised valve springs and decarbonizing the combustion chamber. 1. Use the procedure outlined in the appropriate 1998 Service Manual, Group 9, 4.0L Engine, Removal And Installation, Valve Stem Seal And Spring, to remove and install the revised valve springs (P/N 53010388). 2. Perform the following Decarbonizing Procedure. DECARBONIZING PROCEDURE 1. Operate the vehicle until the vehicle reaches operating temperature. 2. Remove the air tube from the throttle body. 3. With the engine at an idle, spray the entire contents of Mopar Combustion Cleaner, P/N 04318001, directly into the throttle body. Allow the vehicle to load up with the cleaner to the point of almost stalling out. 4. Shut the engine OFF after the entire can is ingested. 5. With the hood closed and the vehicle parked inside the garage, allow the vehicle to soak for two to three hours. This will ensure that the engine will maintain its temperature and will allow proper solvent penetration. 6. Drive the vehicle to fully warm up the engine. 7. If the vehicle is equipped with an automatic transmission, place the gear selector into L, if the vehicle is equipped with a manual transmission, place the transmission into first gear. 8. On a suitable road that will allow the vehicle to be driven safely at the posted speed limit, accelerate the vehicle until the engine reaches 4500 rpm. 9. Hold the engine speed at this rpm for 15 seconds. 10. Slow down and pull to the side of the road, then allow the engine to idle for five seconds. 11. Repeat Steps 7 through 10 two more times. 12. With the vehicle at operating temperature and within the freeze frame data recorded for the diagnostic test, verify that the misfire condition has been corrected. Listed in the Diagnostic Procedure Manual unless the revised pages have been inserted. Part Number Description Qty. 53010388 Springs, Valve 12 04318001 Mopar Combustion Cleaner 1
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Sunday, August 24th, 2008 AT 1:27 PM

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