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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 278 (Engine Controls And Fuel - 3.6L (LGX LF4) - DTC P0117 (LGX) To DTC P0697) >> Diagnostic Information and Procedures >> DTC P0234, P0299, or P16E7: Engine Overboost/Engine Underboost/Turbocharger Bank 1-2 Boost Balance >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Verify the conditions listed below do not exist:
    • Loose clamps, cracks or other damage in the air intake duct system
    • Collapsed or restricted intake duct system
    • Restricted air filter
    • Any air flow restriction
    • Any air leak between the turbochargers and the throttle body
    • Splits, kinks or improper connections at the vacuum hoses
    • Any vacuum leak
    • Restricted, leaking or incorrect routing of vacuum hoses going to the components listed below:
      • Turbocharger wastegate solenoid valves
      • Turbocharger bypass solenoid valves
      • Vacuum tank
      • Turbocharger wastegate actuators
      • Turbocharger bypass valves
    • Damaged or leaking vacuum tank
    • Missing, restricted or leaking exhaust components-Refer to Restricted Exhaust .
    • Exhaust leak between the turbochargers and the exhaust manifold
    • Restricted turbocharger oil supply lines
    • Loose or incorrect installation of any components
      • If a condition exists 

        Repair or replace the affected component as necessary.

      • If none of the conditions exist 
  2. Ignition OFF, disconnect the vacuum supply hose at the turbocharger vacuum pump.
  3. Connect the GE 23738-A  to the pump outlet.
    4. NOTE:

    To determine the absolute vacuum value, subtract the vacuum gauge reading from the barometric pressure.

  4. Engine idling, verify the absolute vacuum value is less than or equal to 15 kPa (4.4 inches Hg).
    • If not within the specified range 

      Repair or replace the vacuum pump.

    • If within the specified range 
  5. Ignition OFF, disconnect all vacuum hoses at the turbocharger vacuum tank and cap or plug the valve outlet ports.
  6. Connect the GE 23738-A  to the vacuum tank inlet port and apply 5 kPa (1.5 inches Hg) of vacuum.
  7. Verify the tank holds vacuum for at least 10 s.
    • If not held for at least 10 s 

      Replace the vacuum tank.

    • If held for at least 10 s 
  8. Connect the vacuum hoses to the tank.
  9. Disconnect the appropriate Q40 Turbocharger Bypass Solenoid Valve output to bypass valve vacuum hose at the solenoid valve and connect the GE 23738-A  to the solenoid valve.
  10. Engine idling.
    11. NOTE:

    To determine the absolute vacuum value, subtract the vacuum gauge reading from the barometric pressure.

  11. Verify the absolute vacuum value toggles between 0 kPa (0 inches Hg) to less than or equal to 15 kPa (4.4 inches Hg), when commanding the Turbocharger Bypass Solenoid Valve between Active and Inactive with a scan tool.
    • If not within the specified range 

      Replace the Q40 Turbocharger Bypass Solenoid Valve.

    • If within the specified range 
  12. Verify the conditions listed below do not exist with the appropriate turbocharger bypass valve assembly:
    • Damage
    • Leaks
    • Restrictions
    • If a condition exists 

      Repair or replace the turbocharger bypass valve as necessary.

    • If none of the conditions exist 
  13. Ignition OFF. Disconnect the appropriate Q42 Turbocharger Wastegate Solenoid Valve output to wastegate actuator vacuum hose at the solenoid valve and connect the GE 23738-A  to the solenoid valve.
  14. Disconnect the harness connector at the Q42 Turbocharger Wastegate Solenoid Valve and connect a 10 A fused jumper wire between terminal 1 of the solenoid valve and B+.
  15. Engine idling.
    16. NOTE:

    To determine the absolute vacuum value, subtract the vacuum gauge reading from the barometric pressure.

  16. Connect a jumper wire between terminal 2 of the solenoid valve and ground. Verify the absolute vacuum value changes from 0 kPa (0 inches Hg) to less than or equal to 15 kPa (4.4 inches Hg) of vacuum when the Q42 Turbocharger Wastegate Solenoid Valve is activated.
    • If not within the specified range 

      Replace the Q42 Turbocharger Wastegate Solenoid Valve.

    • If within the specified range 
  17. Connect the GE 23738-A  to the appropriate wastegate actuator vacuum hose.
  18. Verify the wastegate actuator rod moves when applying between 0-5 kPa of vacuum.
    • If the actuator does not move 
    1. Disconnect the wastegate actuator arm from the wastegate.
    2. Verify the wastegate actuator rod moves when applying between 0-5 kPa vacuum to the actuator.
      • If the actuator does not move, replace the turbocharger wastegate actuator.
      • If the actuator moves, replace the turbocharger.
    • If the actuator moves 
  19. Connect any hoses that were disconnected during previous steps.
  20. Verify the conditions listed below do not exist with the turbocharger assemblies. Refer to Turbocharger Cleaning and Inspection .
    • Worn or damaged wastegate pivot pin
    • Cracked, damaged or worn turbine blades
    • Restricted wastegate, turbine, ports or passages
    • Foreign material
    • If a condition exists 

      Repair or replace the turbocharger(s) as necessary.

    • If none of the conditions exist 
  21. Replace the turbocharger.
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