Very low boost on 2000 GTP


Asked by Feb 18, 2017 at 03:56 PM about the Pontiac Grand Prix

Question type: Maintenance & Repair

My 2000 GTP rather suddenly will only produce very low supercharger boost. There are no computer codes and other than  the low boost problem it runs fine. It has 142,000 miles on it. The supercharger itself is not mechanically noisy, and the supercharger oil has been changed 3 times in its life. What controls the boost and how can I fix this problem??

1 Answer


I found that the "dump valve" was being held partially open at all times. Disconnected the vacuum actuator and soaked the damper actuator shaft where it enters the supercharger body with PB Blaster. Then I worked the shaft by hand until it regained its full range of motion with no sticking or drag. Reassembled linkage and took it out for a test run....... it works fine and comes up to full boost again.

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