PRE-RELEASE
DTC P2261
| DTC P2261 |
| Diagnostic Instructions |
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Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
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Review
Strategy Based Diagnosis
for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions
provides an overview of each diagnostic category.
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| DTC Descriptor |
DTC P2261
Turbocharger Bypass Valve Stuck Closed
| System Description |
The BorgWarner™ dual scroll turbocharger incorporates a wastegate that is controlled by a pressure differential, that is determined by the engine control module (ECM) by means of a PWM solenoid, in order to regulate the pressure ratio of the compressor. A bypass valve is integrated within the unit, and is also controlled by the ECM by utilizing a remotely mounted solenoid to prevent compressor surging and damage from vibrations by opening during abrupt closed throttle conditions. When the valve is commanded open during closed throttle deceleration conditions, the bypass valve allows the air to recirculate in the turbocharger and maintain compressor speed. Within a calibrated range during the closed throttle event, or upon a wide open throttle command, the valve will then close to optimize turbocharger response.
Front wheel drive platforms also incorporate a bypass valve vacuum tank. The purpose of the tank is to provide an instant source of vacuum to the bypass valve, when it is commanded open by the ECM. This results in less pressure buildup under closed throttle conditions, thereby reducing compressor noise and surge.
The purpose of this diagnostic is to determine if the bypass valve is stuck closed. The ECM will first verify the integrity of the following sensors. The ECM then compares the actual measured mass air flow (MAF) to a modeled airflow that is derived from these inputs:
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Throttle position
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Engine speed
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Intake air pressure sensor
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Manifold absolute pressure (MAP) sensor
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| Conditions for Running the DTC |
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DTC P0033, P0034, P0035, P0101, P0102, P0103, P0236, P0237, or P0238 is not set.
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The boost pressure versus the BARO pressure ratio is between1.1-3.3.
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The turbocharger bypass valve has been commanded Open greater than 6% for greater than 1 s immediately after an abrupt closed throttle has occurred and the resulting pressure ratio across the compressor exceeds the calibrated pressure ratio limit.
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The DTCs run continuously when the above conditions have been met.
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| Conditions for Setting the DTC |
The ECM has detected a series of pulsations in the induction system that exceed a calibrated threshold.
| Action Taken When the DTC Sets |
DTC P2261 is a Type B DTC.
| Conditions for Clearing the MIL/DTC |
DTC P2261 is a Type B DTC.
| Reference Information |
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Turbocharger System Description
Electrical Information Reference
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Circuit Testing
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Connector Repairs
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Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs
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DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information.
| Circuit/System Verification |
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Ignition ON, command the Turbocharger Bypass Solenoid Valve ON and OFF with a scan tool. A click should be heard and felt in response to the commands.
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Set up the scan tool for a snapshot of the induction data list. With the parking brake on, the vehicle transmission in neutral, and the engine idling, perform a wide open throttle and then quickly release the accelerator. Review the Boost Pressure Sensor parameter. There should not be any abnormal pulsations of the parameter.
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With the parking brake ON and the engine idling in neutral, perform an audible test of the valve by depressing the throttle wide open, then quickly releasing it to a closed throttle position. A valve that is stuck shut will generate a rapid pulsating sound. There should not be any unusual noise.
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| 4. |
Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
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| Circuit/System Testing |
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Verify the integrity of the turbocharger bypass solenoid valve system by Iinspecting for any the following conditions:
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Vacuum leaks
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Vacuum line restrictions
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Damaged components
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Improper routing or connecting of the vacuum hoses on the turbocharger bypass valve solenoid, the bypass valve, and the bypass valve vacuum tank
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If a condition is found, repair or replace the affected component as necessary.
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If all inspections are normal, test or replace the Q40 Turbocharger Bypass Solenoid Valve.
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| Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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Control Module References
for ECM replacement, setup, and programming
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Charge Air Bypass Valve Replacement
for turbocharger bypass solenoid valve replacement
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