PFI Chart A-4, Power Balance Test

This test checks performance of each cylinder by comparing it to other cylinders. PCM shuts off fuel for a given cylinder in its intake cycle. This measures performance of that cylinder by amount of RPM drop caused by that cylinder not producing a power stroke.

1. Engine should be at operating temperature.
2. RPM drop between cylinders should be within 25 RPM.

Fig 1: PFI Chart A-4, Schematic, Power Balance Test

Courtesy of GENERAL MOTORS CORP.

Fig 2: PFI Flow Chart A-4, Power Balance Test

Courtesy of GENERAL MOTORS CORP.

Fig 3: PFI Flow Chart A-4

When All Diagnosis And Repairs Are Completed, Reconnect ISC Jumper, Clear Codes And Verify Operation