Excessive High Pressure Fuel Pump Roller Pin Movement

Some 2016-2019 Malibu models equipped with the 1.5L 4-cylinder engine (RPO LFV) may have severe low power under acceleration. The low power condition may be due to the ignition timing being extremely retarded on acceleration.

Use GDS 2 to review the ignition timing pattern. If the pattern is extremely retarded during the low power event, remove the high pressure fuel pump roller follower and inspect the roller pin for excessive lateral movement.

Some lateral movement of the roller pin is normal. However, in extreme cases, the pin could walk out enough to protrude past the body of the follower and allow contact with the cylinder head. The normal lateral movement of the pin (Fig. 19, #1) when pushed all the way to one side should not protrude past the body of the follower. (Fig. 19, #2)

Fig. 19

If the roller pin has excessive lateral movement (Fig. 20, #1), with the pin “walking” past the body of the follower (Fig. 20, #2), it will contact and damage the cylinder head follower bore.

Fig. 20

If there is damage to the cylinder head follower bore (Fig. 21, #3) because the pin has protruded past the follower body, the roller body should be replaced. If there is any question about the extent of the excessive pin walk, replace the roller follower and evaluate the components. Replacement of the cylinder head will be required if there is damage to the roller follower bore.

Fig. 21

Once the necessary components are replaced, evaluate low power under acceleration condition.

 

– Thanks to Robert Halas