Turbocharger Boost Pressure

TURBOCHARGER BOOST PRESSURE

Low turbocharger boost pressure can cause poor engine performance and driveability concerns. The following procedure will test the turbocharger boost pressure.

Causes of low boost pressure include the following:

- Restricted air inlet system
- Leak in charge air cooler system
- Damaged wastegate command valve O-rings (5.9L Diesel)
- Restricted/high pressure drop across charge air cooler
- Damaged turbocharger compressor wheel housing
- Turbocharger wastegate stuck open (5.9L Diesel)
- Excessive exhaust restriction
- Stuck or sticking variable geometry components (6.7L diesel engine)
- stuck or inoperative variable geometry actuator (6.7L diesel engine)

Causes of excessively high boost pressure include:

- Turbocharger wastegate stuck closed
- Turbocharger wastegate signal line leaking or damaged
- Damaged turbocharger actuator O-ring (6.7L Diesel)
- Wastegate command valve mechanically stuck in actuated position (5.9L Diesel)
- Stuck or sticking variable geometry components (6.7L diesel engine)
- stuck or inoperative variable geometry actuator (6.7L diesel engine)

Several Diagnostic Trouble Codes (DTCs) can be set that will indicate high or low system boost levels. There is a DTC for circuit faults relating to the electronically controlled wastegate command valve.

Refer to EXHAUST SYSTEM/TURBOCHARGER SYSTEM/CHARGE AIR COOLER AND PLUMBING TESTING for diagnosing of low or high boost pressure due to leaks. Testing and Inspection

NOTE: If oil is present on either the inlet or exhaust side of the turbo charger, check the charge air cooler for evidence of oil. Clean charge air cooler of any oil before starting the engine. Failure to do this can result in severe engine damage.