Engine - MIL ON/Occasional Misfire At Idle
NUMBER: 09-007-06GROUP: Engine
DATE: August 19, 2006
SUBJECT:
Engine Misfire At Idle
OVERVIEW:
This bulletin involves installing revised intake valve locks and intake valves.
MODELS:
2005 - 2006 (KJ) Liberty/Cherokee (International Markets)
2005 - 2006 (ND) Dakota
NOTE:
This bulletin applies to vehicles equipped with a 3.7L engine (sales code EKG).
SYMPTOM/CONDITION:
The customer may experience occasional engine misfire at idle (rough idle). The malfunction indicator lamp may illuminate for single or multiple cylinder misfire.
DIAGNOSIS:
1. Place vehicle in park or neutral.
2. Using a StarSCAN(R) or DRBIII(R), monitor which cylinder is misfiring. Cylinder # 3 is the most likely cylinder to have idle misfire, a cylinder on the opposite bank very very rarely may exhibit a misfire at idle.
NOTE:
When monitoring which cylinder is misfiring, counts should be above 10 per minute.
3. Record misfire counts for 1 minute.
4. Rev engine up to 3500 to 4000 rpm and release, do not hold engine at elevated rpm let it come back down to idle.
5. Monitor the cylinder misfire count for one minute. If the misfire rate does NOT reduce to less than 5 per minute then repeat Step # 4 and re-monitor up to ten times.
6. If the misfire rate DOES reduce to less than 5 per minute, perform the Repair Procedure. If the misfire rate does NOT reduce to less than 5 per minute after repeating Step # 4 ten times this bulletin does not apply and further diagnosis is required.
PARTS REQUIRED:
REPAIR PROCEDURE:
1. Use the procedures outlined in TechCONNECT 9-Engine>Cylinder Head>Intake/Exhaust Valve And Seats>Removal And Installation to replace ALL intake valves and valve locks of the cylinder head that has the misfiring cylinder. Both cylinder heads must have the locks replaced.
2. Repeat Step # 1 through Step # 5 of the Diagnosis monitoring all cylinders for misfire after the repair work is completed.
3. A cylinder on the opposite bank very very rarely may exhibit a misfire at idle. If the opposite bank now has a misfire, then the new keepers have allowed a non-rotating valve with uneven wear to rotate and induce a misfire. In this case the intake valves on this head must now be replaced.
POLICY:
Reimbursable within the provisions of the warranty.
TIME ALLOWANCE:
FAILURE CODE:
Disclaimer:
This bulletin is supplied as technical information only and is not an authorization for repair.