Boost Pressure Test

Boost Pressure Test Location:

Boost Pressure Gage:

WARNING: Do not perform this test with anyone in the area around the vehicle. The wheels of the vehicle should be blocked to prevent the vehicle from moving forward. Failure to take proper precautions may result in personal injury and damage to the vehicle.

IMPORTANT: To further determine the condition of the turbocharger, the following boost test must be performed. It is recommended that this test be performed only after the "Turbocharger Inspection" and "Waste-Gate Actuator Inspection" have been completed:

Garage Test:
1. Remove the front center intake duct (crossover) bolt. This bolt is drilled into the air plenum chamber.
2. Connect the J 39307 pressure gage.
3. Operate the vehicle at wide open throttle (WOT) against the transmission torque converter at stall speed.

CAUTION: This test should not exceed 10 seconds at the converter stall speed to obtain the gage reading. Reverse should not be used for the converter stall test.

4. Observe the gauge reading.

The boost pressure obtained by performing the above test should be at least 2 psi at the torque converter stall speed. If the turbocharger is operating at 2 psi or more, the turbocharger is operating properly and the problem is with the engine.

Road Test:
1. Remove the front center intake duct (crossover) bolt. This bolt is drilled into the air plenum chamber:
- Install J 39307-1 adapter with a 6 to 7 foot length of 3/16 inch I.D.rubber line.
- Route rubber line into vehicle cab.
- Connect J 28474 pressure gauge to the end of the line.
2. Test drive the vehicle with a passenger watching the gauge:
- Allow vehicle to coast at engine idle speed in first gear.
- Press the accelerator pedal to the floor while the passenger notes the boost pressure reading.

A boost pressure of 14 kPa (2 psi) or more indicates the turbocharger is operating properly.

NOTE: The 14 kPa (2 psi) is for quick accelerations only. The pressure reading can climb above 14 kPa (2 psi) under heavy loads. During deceleration, the pressure reading may go down.