[noncommittal_name]

Took my VSport to the track for the first time since winter and noticed something a little strange. CEL came on with pending DTC P0299 (turbo underboost). Previously I had been getting a CEL at the track but it was for turbo overboost. I started paying attention and saw that the turbos showed normal boost for about a half lap and then after that would stay at around 1-2 PSI for the rest of the heat. She wasn't exactly slow under those conditions but not blazing fast either. CEL turned off the next day. Everything else is completely normal.

My working theory is that the ECM is limiting the boost for some reason. Wondering if anyone has had a similar experience with an LF3 or other turbo GM engine.

I logged data for all of this but haven't looked at it in detail yet. If anyone has thoughts on what I should be looking for in it that would be greatly appreciated too!

 

[DriveOn]

I’ve had similar problems, both overboost and underboost DTC’s. Once because I over revved the engine while in manual shift mode and once when the vacuum line to a bypass valve blew off. It also happened a couple of times that I attribute to a cracked inlet air hose to the charge air cooler. As I recall during most of the above scenarios my boost was knocked down quite a bit more than one or two PSI. The good news is that in the end no harm done and the car runs as good as it ever did.

 

[noncommittal_name]

Thanks for the input DriveOn.

In the situations where it was due to the vacuum line or cracked inlet air hose did the car give normal amounts of boost at any point prior to repairing the issue?

 

[DriveOn]

I had several problems with my boost 'system' over several months so it's hard to remember the various scenarios. That said, I'm pretty sure I have had normal boost with a DTC P0299 set.
If I were to diagnose the problem I'd start with the simple, easy to access items. First the By-Pass-Valves, one on each side of the Charge Air Cooler. They allow boost to escape when the throttle plate closes. Of course if there is a problem with a valve they can allow boost to escape anytime. I've read that they are a poor man's version, comprised of a flimsy rubber flapper that maybe doesn't seal as we'd like. Regardless, each valve has 2 connections that I have had problems with. In the attached photo, item 1a shows a broken clamp, as compared to item 1b which is normal. That clamp should ensure a tight and constant connection to the charge air cooler. At one point I used mechanics wire to cinch the ByPassValves up to the metal air cooler tube. Now I'm using an aftermarket BOV (Blow Off Valve). Also in the photo, items 2a/b show a connector that fits to a vacuum tube that ultimately allows the ECU to open the valve. That thing blew off on me once because the plastic locking mechanism was broken.

 

[DriveOn]

Maybe this will help. It was interesting reading but didn't do much for resolving my problems. Sorry about the formatting, I don't know how to make it easier to read.

DTC P0234 or P0299 Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle See: Testing and Inspection\Initial Inspection and Diagnostic Overview\Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Review Strategy Based Diagnosis See: Testing and Inspection\Initial Inspection and Diagnostic Overview\Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions See: Testing and Inspection\Initial Inspection and Diagnostic Overview\Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P0234
Engine Overboost
DTC P0299
Engine Underboost
Circuit/System Description
The boost pressure sensor is integrated with the turbocharger boost/intake air temperature sensor. The boost pressure sensor measures the range of pressures between the turbocharger and the throttle body. The sensor used on this engine is a three atmosphere sensor. Pressure in this portion of the induction system is affected by engine speed, throttle opening, turbocharger boost pressure, intake air temperature (IAT), barometric pressure (BARO), and the efficiency of the charge air cooler.
The sensor provides a signal voltage to the engine control module (ECM), relative to the pressure changes. Under normal operation the greatest pressure that can exist in this portion of the induction system at ignition ON, engine OFF is equal to the BARO. When the engine is operated at wide-open throttle (WOT) the turbocharger can increase the pressure to near 240 kPa (34.8 psi). The pressure is equal to the BARO when the engine is idling or decelerating.
P0234

The turbochargers each incorporate a vacuum operated wastegate that is controlled by the engine control module (ECM) by means of a remotely mounted solenoid, to regulate the pressure ratio of the compressor. The wastegate valve vacuum source is provided by a vacuum pump which is driven off the end of the right hand exhaust camshaft.
At idle the turbocharger wastegate solenoids are open. When the engine load and RPM increase under a wide open throttle, the turbocharger wastegate valves close to increase boost pressure. When the proper level of boost pressure is attained, the ECM will partially open the wastegates to maintain the boost pressure level. When the throttle closes, the ECM commands the wastegates to open to reduce the speed of the turbines.
Conditions for Running the DTC
DTC P0010, P0011, P0013, P0014, P0020, P0021, P0023, P0024, P0033, P0034, P0035, P0068, P0090, P0091, P0092, P00C0, P00C1, P00C2, P00C8, P00C9, P00CA, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0122, P0123, P0128, P0191, P0192, P0193, P0222, P0223, P0236, P0237, P0238, P026A, P0601, P0604, P0606, P0697, P06A3, P1682, P16A0, P16A1, P16A2, P16F3, P2088, P2089, P2090, P2091, P2092, P2093, P2094, P2095, P2101, P2122, P2123, P2127, P2128, P2135, P2138, P2176, P2227, P2228, P2229, P222C, P222D, P2230, or U0073 is not set.
Engine speed is between 1,500-6,500 RPM.
Desired boost pressure is between 70-245 kPa (10.1-35.5 PSI).
BARO is between 60-120 kPa (8.7-17.4 PSI).
Engine coolant temperature (ECT) is between -40 to +120°C (-40 to +248°F). Intake air temperature (IAT) is between -40 to +80°C (-40 to +176°F). Desired boost pressure is greater than basic boost pressure.
The DTCs run continuously within the enabling conditions.
Conditions for Setting the DTC
The ECM has detected the difference between desired and actual boost pressure is not within a calibrated threshold.
Action Taken When the DTC Sets
DTC P0234 and P0299 are Type B DTCs.
Conditions for Clearing the DTC
DTC P0234 and P0299 are Type B DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics (LFX) See: Diagrams\Electrical\Powertrain Management\System DiagramEngine Controls Schematics (LF3) See: Diagrams\Electrical\Powertrain Management\System Diagram
Connector End View Reference
Component Connector End Views See: Diagrams\Connector Views
Description and Operation
Turbocharger System Description See: Powertrain Management\Fuel Delivery and Air Induction\Turbocharger\Description and Operation
Electrical Information Reference
Circuit Testing See: Testing and Inspection\Component Tests and General Diagnostics\General Electrical Diagnostic Procedures\Circuit Testing\Circuit Testing
Connector Repairs See: Testing and Inspection\Component Tests and General Diagnostics\General Electrical Diagnostic Procedures\Connector Repairs\Connector Repairs
Testing for Intermittent Conditions and Poor Connections See: Testing and Inspection\Component Tests and General Diagnostics\General Electrical Diagnostic Procedures\Circuit Testing\Testing for Intermittent Conditions and Poor Connections

Wiring Repairs See: Testing and Inspection\Component Tests and General Diagnostics\General Electrical Diagnostic Procedures\Wiring Repairs\Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions See: Diagnostic Trouble Code Descriptions\Powertrain Diagnostic
Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References See: Testing and Inspection\Programming and Relearning\Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify DTC P0033, P0034, P0035, P00C0, P00C1, P00C2, P0236, P0237, P0238, P0243, P0245, P0246, P0247, P0249,
or P0250 is not set.
¤ If any of the DTCs are set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle See: Diagnostic Trouble Code Descriptions\Diagnostic Trouble Code (DTC) List - Vehicle.
¤ If none of the DTCs are set
3. Verify the scan tool Barometric Pressure Sensor Bank 1 and Bank 2 parameters are within the range specified in the Altitude Versus Barometric Pressure See: Powertrain Management\Computers and Control Systems\Specifications\Altitude Versus Barometric Pressure table.
¤ If either parameter is not within the specified range
Refer to the corresponding DTC P2227-P2230 (LFX) See: P2227DTC P2227-P2230 (LF3) See: P2227 or DTC P222B-P222E See:
P222B.
¤ If both parameters are within the specified range
4. Verify the scan tool MAP Sensor and Barometric Pressure Sensor Bank 1 and Bank 2 parameters are within 3 kPa (0.4 psi).
¤ If not within 3 kPa (0.4 psi) Refer to DTC P0106 See: P0106.
¤ If within 3 kPa (0.4 psi)
5. Verify the scan tool Boost Pressure Sensor and Barometric Pressure Sensor Bank 1 and Bank 2 parameters are within 3 kPa (0.4 psi).
¤ If not within 3 kPa (0.4 psi) Refer to DTC P0236 See: P0236.
¤ If within 3 kPa (0.4 psi)
Note: This step is intended to verify the electronic bypass solenoid valve operation.

6. Verify a click is heard or felt from the corresponding Q40 Turbocharger Bypass Solenoid Valve when commanding the Turbocharger Bypass Solenoid Valve Bank 1 or Bank 2 between Active and Inactive with a scan tool.
¤ If a click is not heard or felt Refer to Circuit/System Testing.
¤ If a click is heard or felt
7. Engine Idling.
Note: This step is intended to verify the vacuum operated bypass valve operation.
8. Verify a click is heard or felt from the corresponding turbocharger bypass valve when commanding the Turbocharger Bypass Solenoid Valve Bank 1 or Bank 2 between Active and Inactive with a scan tool.
¤ If a click is not heard or felt Refer to Circuit/System Testing.
¤ If a click is heard or felt
9. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
10. Verify a DTC does not set.
¤ If a DTC sets
Refer to Circuit/System Testing.
¤ If a DTC does not set
11. All OK Circuit/System Testing
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 See: Engine, Cooling and Exhaust\Exhaust System\Testing and Inspection\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.
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.
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.
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
17. 18.
¤ If
1. 2.
¤
¤ ¤ If
19. 20.
within the specified range
Connect the GE 23738-A to the appropriate wastegate actuator vacuum hose. Verify the wastegate actuator rod moves when applying between 0-5 kPa of vacuum.
the actuator does not move
Disconnect the wastegate actuator arm from the wastegate.
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.
the actuator moves
Connect any hoses that were disconnected during previous steps.
Verify the conditions listed below do not exist with the turbocharger assemblies. Refer to Turbocharger Cleaning and Inspection See: Engine, Cooling and Exhaust\Engine\Service and Repair\Overhaul\Repair Instructions\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. Repair Instructions
Perform the Diagnostic Repair Verification See: Verification Tests after completing the repair.

Charge Air Bypass Valve Solenoid Replacement (LF3) See: Powertrain Management\Fuel Delivery and Air Induction\Exhaust Bypass Valve\Service and Repair for turbocharger bypass solenoid valve replacement
Charge Air Bypass Valve Replacement - Right Side (LF3) See: Powertrain Management\Fuel Delivery and Air Induction\Exhaust Bypass Valve\Service and Repair for turbocharger bypass valve replacement bank 1
Charge Air Bypass Valve Replacement - Left Side (LF3) See: Powertrain Management\Fuel Delivery and Air Induction\Exhaust Bypass Valve\Service and Repair for turbocharger bypass valve replacement bank 2
Turbocharger Wastegate Actuator Vacuum Tank Replacement (LF3) See: Powertrain Management\Fuel Delivery and Air Induction\Wastegate Actuator\Service and Repair\Turbocharger Wastegate Actuator Vacuum Tank Replacement Turbocharger Wastegate Regulator Solenoid Valve Replacement (LF3) See: Powertrain Management\Fuel Delivery and Air Induction\Wastegate Actuator\Service and Repair\Turbocharger Wastegate Regulator Solenoid Valve Replacement Turbocharger Wastegate Actuator Replacement - Right Side See: Powertrain Management\Fuel Delivery and Air Induction\Wastegate Actuator\Service and Repair\Turbocharger Wastegate Actuator Replacement - Right Side Turbocharger Wastegate Actuator Replacement - Left Side See: Powertrain Management\Fuel Delivery and Air Induction\Wastegate Actuator\Service and Repair\Turbocharger Wastegate Actuator Replacement - Left Side
Vacuum Pump Removal See: Engine, Cooling and Exhaust\Engine\Service and Repair\Overhaul\Repair Instructions\Vacuum Pump Removal
Vacuum Pump Installation See: Engine, Cooling and Exhaust\Engine\Service and Repair\Overhaul\Repair Instructions\Vacuum Pump Installation
Control Module References See: Testing and Inspection\Programming and Relearning\Control Module References for ECM replacement, programming and setup

 

[Grumpydave]

Same code, same symptoms including low boost gauge readings. Ended up being a badly kinked partially collapsed vacuum hose under the vacuum tank on bank one. Normal driving ,all good. Playing to any degree , CEL on codes set. New hose, all is good...so far.

 

[noncommittal_name]

Old thread but I think I've made some progress on this. The problem started occurring on the street as well. I bled the intercooler system and it's no longer causing the issue on the street. Great youtube video on the procedure. I purchased the kit from tapout rather than putting one together myself. It takes some time and patience.

Fingers crossed this solves the issue on track as well. I just purchased a dedicated track car so I probably won't find out for a little while.

 

[sergiosalasgarcia26]

Maybe this will help. It was interesting reading but didn't do much for resolving my problems. Sorry about the formatting, I don't know how to make it easier to read. DTC P0234 or P0299 Diagnostic Instructions Perform the Diagnostic System Check - Vehicle See: Testing and Inspection\Initial Inspection and Diagnostic Overview\Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis See: Testing and Inspection\Initial Inspection and Diagnostic Overview\Strategy Based Diagnosis for an overview of the diagnostic approach. Diagnostic Procedure Instructions See: Testing and Inspection\Initial Inspection and Diagnostic Overview\Diagnostic Procedure Instructions provides an overview of each diagnostic category. DTC Descriptor DTC P0234 Engine Overboost DTC P0299 Engine Underboost Circuit/System Description The boost pressure sensor is integrated with the turbocharger boost/intake air temperature sensor. The boost pressure sensor measures the range of pressures between the turbocharger and the throttle body. The sensor used on this engine is a three atmosphere sensor. Pressure in this portion of the induction system is affected by engine speed, throttle opening, turbocharger boost pressure, intake air temperature (IAT), barometric pressure (BARO), and the efficiency of the charge air cooler. The sensor provides a signal voltage to the engine control module (ECM), relative to the pressure changes. Under normal operation the greatest pressure that can exist in this portion of the induction system at ignition ON, engine OFF is equal to the BARO. When the engine is operated at wide-open throttle (WOT) the turbocharger can increase the pressure to near 240 kPa (34.8 psi). The pressure is equal to the BARO when the engine is idling or decelerating. P0234 The turbochargers each incorporate a vacuum operated wastegate that is controlled by the engine control module (ECM) by means of a remotely mounted solenoid, to regulate the pressure ratio of the compressor. The wastegate valve vacuum source is provided by a vacuum pump which is driven off the end of the right hand exhaust camshaft. At idle the turbocharger wastegate solenoids are open. When the engine load and RPM increase under a wide open throttle, the turbocharger wastegate valves close to increase boost pressure. When the proper level of boost pressure is attained, the ECM will partially open the wastegates to maintain the boost pressure level. When the throttle closes, the ECM commands the wastegates to open to reduce the speed of the turbines. Conditions for Running the DTC DTC P0010, P0011, P0013, P0014, P0020, P0021, P0023, P0024, P0033, P0034, P0035, P0068, P0090, P0091, P0092, P00C0, P00C1, P00C2, P00C8, P00C9, P00CA, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0122, P0123, P0128, P0191, P0192, P0193, P0222, P0223, P0236, P0237, P0238, P026A, P0601, P0604, P0606, P0697, P06A3, P1682, P16A0, P16A1, P16A2, P16F3, P2088, P2089, P2090, P2091, P2092, P2093, P2094, P2095, P2101, P2122, P2123, P2127, P2128, P2135, P2138, P2176, P2227, P2228, P2229, P222C, P222D, P2230, or U0073 is not set. Engine speed is between 1,500-6,500 RPM. Desired boost pressure is between 70-245 kPa (10.1-35.5 PSI). BARO is between 60-120 kPa (8.7-17.4 PSI). Engine coolant temperature (ECT) is between -40 to +120°C (-40 to +248°F). Intake air temperature (IAT) is between -40 to +80°C (-40 to +176°F). Desired boost pressure is greater than basic boost pressure. The DTCs run continuously within the enabling conditions. Conditions for Setting the DTC The ECM has detected the difference between desired and actual boost pressure is not within a calibrated threshold. Action Taken When the DTC Sets DTC P0234 and P0299 are Type B DTCs. Conditions for Clearing the DTC DTC P0234 and P0299 are Type B DTCs. Reference Information Schematic Reference Engine Controls Schematics (LFX) See: Diagrams\Electrical\Powertrain Management\System DiagramEngine Controls Schematics (LF3) See: Diagrams\Electrical\Powertrain Management\System Diagram Connector End View Reference Component Connector End Views See: Diagrams\Connector Views Description and Operation Turbocharger System Description See: Powertrain Management\Fuel Delivery and Air Induction\Turbocharger\Description and Operation Electrical Information Reference Circuit Testing See: Testing and Inspection\Component Tests and General Diagnostics\General Electrical Diagnostic Procedures\Circuit Testing\Circuit Testing Connector Repairs See: Testing and Inspection\Component Tests and General Diagnostics\General Electrical Diagnostic Procedures\Connector Repairs\Connector Repairs Testing for Intermittent Conditions and Poor Connections See: Testing and Inspection\Component Tests and General Diagnostics\General Electrical Diagnostic Procedures\Circuit Testing\Testing for Intermittent Conditions and Poor Connections Wiring Repairs See: Testing and Inspection\Component Tests and General Diagnostics\General Electrical Diagnostic Procedures\Wiring Repairs\Wiring Repairs DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions See: Diagnostic Trouble Code Descriptions\Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References See: Testing and Inspection\Programming and Relearning\Control Module References for scan tool information Circuit/System Verification 1. Ignition ON. 2. Verify DTC P0033, P0034, P0035, P00C0, P00C1, P00C2, P0236, P0237, P0238, P0243, P0245, P0246, P0247, P0249, or P0250 is not set. ¤ If any of the DTCs are set Refer to Diagnostic Trouble Code (DTC) List - Vehicle See: Diagnostic Trouble Code Descriptions\Diagnostic Trouble Code (DTC) List - Vehicle. ¤ If none of the DTCs are set 3. Verify the scan tool Barometric Pressure Sensor Bank 1 and Bank 2 parameters are within the range specified in the Altitude Versus Barometric Pressure See: Powertrain Management\Computers and Control Systems\Specifications\Altitude Versus Barometric Pressure table. ¤ If either parameter is not within the specified range Refer to the corresponding DTC P2227-P2230 (LFX) See: P2227DTC P2227-P2230 (LF3) See: P2227 or DTC P222B-P222E See: P222B. ¤ If both parameters are within the specified range 4. Verify the scan tool MAP Sensor and Barometric Pressure Sensor Bank 1 and Bank 2 parameters are within 3 kPa (0.4 psi). ¤ If not within 3 kPa (0.4 psi) Refer to DTC P0106 See: P0106. ¤ If within 3 kPa (0.4 psi) 5. Verify the scan tool Boost Pressure Sensor and Barometric Pressure Sensor Bank 1 and Bank 2 parameters are within 3 kPa (0.4 psi). ¤ If not within 3 kPa (0.4 psi) Refer to DTC P0236 See: P0236. ¤ If within 3 kPa (0.4 psi) Note: This step is intended to verify the electronic bypass solenoid valve operation. 6. Verify a click is heard or felt from the corresponding Q40 Turbocharger Bypass Solenoid Valve when commanding the Turbocharger Bypass Solenoid Valve Bank 1 or Bank 2 between Active and Inactive with a scan tool. ¤ If a click is not heard or felt Refer to Circuit/System Testing. ¤ If a click is heard or felt 7. Engine Idling. Note: This step is intended to verify the vacuum operated bypass valve operation. 8. Verify a click is heard or felt from the corresponding turbocharger bypass valve when commanding the Turbocharger Bypass Solenoid Valve Bank 1 or Bank 2 between Active and Inactive with a scan tool. ¤ If a click is not heard or felt Refer to Circuit/System Testing. ¤ If a click is heard or felt 9. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. 10. Verify a DTC does not set. ¤ If a DTC sets Refer to Circuit/System Testing. ¤ If a DTC does not set 11. All OK Circuit/System Testing 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 See: Engine, Cooling and Exhaust\Exhaust System\Testing and Inspection\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. 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. 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. 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 17. 18. ¤ If 1. 2. ¤ ¤ ¤ If 19. 20. within the specified range Connect the GE 23738-A to the appropriate wastegate actuator vacuum hose. Verify the wastegate actuator rod moves when applying between 0-5 kPa of vacuum. the actuator does not move Disconnect the wastegate actuator arm from the wastegate. 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. the actuator moves Connect any hoses that were disconnected during previous steps. Verify the conditions listed below do not exist with the turbocharger assemblies. Refer to Turbocharger Cleaning and Inspection See: Engine, Cooling and Exhaust\Engine\Service and Repair\Overhaul\Repair Instructions\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. Repair Instructions Perform the Diagnostic Repair Verification See: Verification Tests after completing the repair. Charge Air Bypass Valve Solenoid Replacement (LF3) See: Powertrain Management\Fuel Delivery and Air Induction\Exhaust Bypass Valve\Service and Repair for turbocharger bypass solenoid valve replacement Charge Air Bypass Valve Replacement - Right Side (LF3) See: Powertrain Management\Fuel Delivery and Air Induction\Exhaust Bypass Valve\Service and Repair for turbocharger bypass valve replacement bank 1 Charge Air Bypass Valve Replacement - Left Side (LF3) See: Powertrain Management\Fuel Delivery and Air Induction\Exhaust Bypass Valve\Service and Repair for turbocharger bypass valve replacement bank 2 Turbocharger Wastegate Actuator Vacuum Tank Replacement (LF3) See: Powertrain Management\Fuel Delivery and Air Induction\Wastegate Actuator\Service and Repair\Turbocharger Wastegate Actuator Vacuum Tank Replacement Turbocharger Wastegate Regulator Solenoid Valve Replacement (LF3) See: Powertrain Management\Fuel Delivery and Air Induction\Wastegate Actuator\Service and Repair\Turbocharger Wastegate Regulator Solenoid Valve Replacement Turbocharger Wastegate Actuator Replacement - Right Side See: Powertrain Management\Fuel Delivery and Air Induction\Wastegate Actuator\Service and Repair\Turbocharger Wastegate Actuator Replacement - Right Side Turbocharger Wastegate Actuator Replacement - Left Side See: Powertrain Management\Fuel Delivery and Air Induction\Wastegate Actuator\Service and Repair\Turbocharger Wastegate Actuator Replacement - Left Side Vacuum Pump Removal See: Engine, Cooling and Exhaust\Engine\Service and Repair\Overhaul\Repair Instructions\Vacuum Pump Removal Vacuum Pump Installation See: Engine, Cooling and Exhaust\Engine\Service and Repair\Overhaul\Repair Instructions\Vacuum Pump Installation Control Module References See: Testing and Inspection\Programming and Relearning\Control Module References for ECM replacement, programming and setup