P2261

DTC P2261

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P2261
- Turbocharger Bypass Valve Stuck Closed

System Description

The BorgWarner(TM) 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 compressor bypass valve also controlled by the ECM by utilizing a remotely mounted solenoid integrated into the unit to prevent compressor surging and damage from vibrations by opening during abrupt closed throttle conditions. When the valve is 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 turbo response. The compressor bypass valve is also known as the turbocharger bypass valve.

The purpose of this diagnostic is to determine if the turbocharger 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:

* The throttle position (TP)
* The engine speed
* The boost pressure sensor
* The manifold absolute pressure (MAP) sensor

Conditions for Running the DTC

* DTCs P0033, P0034, P0035, P0096, P0097, P0098, P0099, P0100, P0101, P0102, P0103, P0106, P0107, P0108, P0121, P0122, P0123, P0221, P0222, P0223, P0234, P0236, P0237, P0238, P0299, P2227, P2228, P2229, are not set.
* The boost pressure versus the BARO pressure ratio is between 1.1-3.3.
* The Turbocharger bypass valve has been commanded ON for greater than 1 second immediately after an abrupt closed throttle has occurred and the resulting pressure ratio across the compressor exceeds the calibrated pressure ratio limit.
* The battery voltage is between 10-18 volts.
* This DTC runs continuously within the enabling conditions.

Conditions for Setting the DTC

The ECM by comparing the measured MAF to the modeled MAF 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.

Diagnostic Aids

* A restriction that exists in the exhaust system will hinder the performance of the engine and the turbocharger. Refer to Restricted Exhaust. Restricted Exhaust
* 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. One of the most noticeable aspects of a valve that is stuck shut is the turkey gobble sound that is generated with compressor surge.
* For additional turbocharger and boost system information, refer to Turbocharger System Description and Boost Control System Description.

Circuit/System Verification

* Inspect for any damage, improper routing or connecting of the vacuum hoses on the turbocharger bypass valve solenoid and the turbocharger bypass valve.
* Use the scan tool output controls to command the TC Bypass Solenoid ON and OFF. An audible click should be heard and felt.
* Set up the scan tool for a snapshot of the induction data list. With the emergency 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 and look for any abnormal pulsations of the parameter.

Circuit/System Testing

Clear the DTC and operate the vehicle within the conditions for Running the DTC.

If the DTC cannot be cleared or continues to reset, then replace the turbocharger bypass valve solenoid.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Charge Air Bypass Valve Solenoid Replacement
* Refer to Programming and Relearning for ECM setup and programming. Programming and Relearning