Tim’s Garage Episode 17: Saturn Sky Redline Turbo Wastegate Actuator Adjustment / Solstice GXP

In this episode, I outline how I resolved a low-building and less-than-thrilling boost pattern. After many rounds of tuning and some less than uplifting boost numbers, I could not help but think there was more power to be found. The observed condition was slow but linear, climbing boost to 6000 RPM where it would peak around 5500 RPM. Another observation was that at high RPM when you decreased throttle position, boost would increase slightly. It “seemed like” the wastegate might be leaking or not working correctly and I decided to check the mechanical settings and found an incredibly EASY FIX. Follow along and observe how easy the correction was.

A fellow Sky lister named Andreas provided this more detailed information:

In the official turbocharger wastegate actuator adjustment technical service bulletin they say 3 turns tighten from (same as Tuner Westers Garage recommends)

1) Remove the turbocharger heat shield.

2) Loosen the lock nut (2).

3) Hand tighten the lock nut (1) until it is seated on the wastegate arm and slight spring tension is observed.

Note: Ensure the wastegate actuator rod does not rotate during the tightening procedure. If the rod does rotate, it will be necessary to start the procedure again.

4) Mark the lock nut (1) with a paint pen to mark a starting position and tighten three complete turns.

Note: After the lock nut (1) has been tightened three complete turns, it should not move for the remainder of the procedure.

5) While holding the wastegate rod tighten the nut (2) hand tight.

6) Tighten the nut (2) while holding nut (1) in place to 10 N·m(89 lb in). Apply threadlock (P/N 12345493) to the wastegate actuator rod threads on both sides .



Note: The wastegate adjustment is sometimes a very fine process. When adjusting the wastegate, only small adjustments should be made. Loosen one nut at a time and only adjust the nut one turn at a time; then tighten the other nut against the shaft and test drive to verify. This may have to be performed several times to achieve the desired boost level. To ensure proper adjustment, the vehicle should be at full operating temperature when testing. The vehicle will be very hot and may need to cool between adjustments. Too large of an adjustment can cause repeat DTCs.

Turbocharger Engine Underboost
To increase boost, adjust the nuts (in) towards the actuator; in essence making the shaft shorter.

Turbocharger Engine Overboost
To reduce boost, adjust the nuts (out) towards the end of the shaft; in essence making the shaft longer.

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