Purpose
To determine if EBP and MAP change, as VGT control changes
This is a manual test that allows the technician to set VGT duty to low, medium or high.
Tools
• EST with MasterDiagnostics® software
• EZ-Tech® interface cable
Procedure
NOTE: The KOER VGT Test can only be done with the EST using MasterDiagnostics® software.
1. With the engine running, select D_KOER_AirManagement.ssn from the open session file window and select OPEN to open the session. Monitor EBP and MAP at low, medium, and high duty cycle.
2. Select Diagnostics from the menu bar.
3. Select Key-On Engine-Running Tests from the drop down menu.
NOTE: When using the EST to do KOEO or KOER diagnostic tests, Standard Test is always selected
and run first. If the ignition switch is not cycled, the Standard Test does not have to be run again.
4. From the KOER Diagnostics menu, select Low Duty cycle from VGT Tests, and select Run to start test:
Use the suggested toggle sequence below, to check turbocharger operation from one duty cycle to the other.
• Low to medium
• Medium to high
• High to low
• Low to high
To toggle between duty cycles, select one of the two remaining duty cycles and select Run to start.
As the VGT duty cycle increases when toggled through the low, medium, and high duty cycles, the EBP and MAP values should increase in relationship to the VGT duty cycle. Conversely, when duty cycle is reduced, there should be a reduction to the EBP and MAP values.
If the ECM does not receive a request from the EST, after about 40 seconds, the test will automatically end and the engine will return to normal operation.
5. Record results on Diagnostics Form.
• Did EBP and MAP change for each transition?
— If yes, continue to the next diagnostic test.
— If no, turbocharger is suspect for low power condition. See “Low Power (Turbocharger Assembly and Actuator)”
in Section 4.
Possible Causes
• Intake or exhaust leaks
• Intake or exhaust restrictions
• Plugged EBP tube assembly
• Biased MAP or EBP sensor
• Failed VGT actuator
• Failed turbocharger
• Failed EGR control valve
