Valve Lifter Orientation Verification Active Fuel Management

Tools Required

J 38722 Compression Tester

1. Install a scan tool and use the appropriate scan tool selections to check for DTCs indicating a misfire on one of the three active fuel management (AFM) cylinders (cylinders 1, 3 and 5).

•	If misfire DTCs are present on any of these cylinders, proceed to step 2.

•	If no misfire DTCs are present on any of these cylinders, refer to Symptoms - Engine Mechanical.

2. Disable the fuel system by removing the fuel pump fuse.
3. Using the J 38722 , record the compression readings from the suspect cylinder.

•	If AFM lifter is installed backwards, the suspect cylinder will generate compression numbers within specifications. This is because when cranking, engine RPM is not great enough to generate the oil pressure needed to disengage the AFM lifter locking pin.

•	If compression numbers are not within specifications, refer to Symptoms - Engine Mechanical.

4. Enable the fuel system by reinstalling the fuel pump fuse.
5. Start the engine and observe the compression gage.

If little or no compression is observed at this time, then the most likely cause is 1 or more AFM lifters on this cylinder are installed backwards. This is because with the engine running at idle, sufficient oil pressure can be generated to disengage the AFM locking pin. Replace all AFM lifters as an assembly. Refer to Valve Lifter Replacement.

6. After lifter repairs are completed:

•	Verify proper AFM operation using published diagnostic procedures.

•	Clears ALL codes set during the diagnostic process.