LS1 383ci Turbo overboosting problem

[MichaelParticipant VY Calais 383ci GT42 turbo. View build HERE Member since: March 2, 2015 Posts: 208]

Hi all.

In some real trouble only a few days out of powercruise.

Car was fine running on 98octane. Changing to E85 now and the turbo is overboosting to 15psi before the tuner backs off (still climbing).

Tuner has dropped the exhaust and checked the wastegate diaphragm (turbosmart progate 50mm). Diaphragm is fine.
Have disconnected the boost controller and run straight off the 7pound spring in the wastegate and still no difference.

Still not working. Can’t think of what else would cause this.

• This topic was modified 9 years, 9 months ago by  Michael.

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