Home » Duramax LLY » Duramax LLY – TURBOCHARGER OPERATION – Boost Pressure Test

Duramax LLY – TURBOCHARGER OPERATION – Boost Pressure Test

Boost pressure is checked with a compound vacuum/pressure gauge. A road test under boost conditions is required. Procedure is as follows:
1. Attach compound gauge hose to fitting on air inlet tube, air horn, or turbocharger outlet.

2. Route hose to passenger side-window and into vehicle interior.

3. Road test vehicle. Have helper either drive or observe test gauge. Press accelerator pedal to wide open position and note gauge reading. A gauge reading of 2 psi (14 kPa) or more indicates normal operation.

NOTE: During deceleration, boost level may decrease, this is normal.

4. If gauge reading is zero, or well below 2 psi (14 kPa), check complete air intake and exhaust system for leaks and repair as needed. Also check vacuum actuator, and accelerator pedal potentiometer. Run electrical check with Tech 2 scan tool if electrical system problems are suspected.


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