Fuel Cut at 12psi on 57 Trim CT26 - Stiff Aftermarket Wastegate Actuator

Turbointermediate✓ OP Confirmed

Problem

1988 7M-GTE with CT26 57 trim billet compressor wheel hitting fuel cut (code 34) at WOT in 2nd gear or higher, with boost reaching approximately 12 psi despite a stock, unshimmed wastegate.

Fuel cut at WOT in 2nd gear or higherDiagnostic code 34 (knock sensor / fuel cut)Boost reaching 12 psi with stock wastegate (should be 7-8 psi)Problem persisted even after reverting to stock airbox and paper filter

Root Cause

The aftermarket wastegate actuator that came with the Driftmotion 57 trim CT26 kit was too stiff — it required 15 psi to open, compared to the stock OEM actuator which opens at 7-8 psi. This allowed boost to climb well beyond the intended wastegate cracking pressure, triggering the factory fuel cut.

Confidence

Moderate confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted September 2022 on SupraForums.com