The M57 diesel engine, renowned for its performance and reliability, can be further enhanced with an EGR delete. This modification offers potential benefits like increased fuel economy and reduced carbon buildup. This guide outlines a simple, reversible EGR delete method, focusing on manipulating the EGR valve’s feedback sensor. This technique avoids the drawbacks of physically blocking the EGR valve, such as decreased mileage and multiple error codes.
Understanding the M57 EGR System and the Delete Process
The Exhaust Gas Recirculation (EGR) system recirculates a portion of exhaust gases back into the intake manifold. While designed to reduce NOx emissions, the EGR system can contribute to carbon buildup in the intake manifold over time, potentially affecting performance. An EGR delete aims to eliminate this issue.
This method, credited to TDIwyse, involves disconnecting the feedback sensor on the EGR valve. This tricks the DDE (Digital Diesel Electronics) into believing the EGR valve is functioning correctly, preventing limp mode and reducing error codes.
Disconnecting the EGR valve motor entirely triggers limp home mode. However, disconnecting the feedback sensor (likely a Hall effect sensor) achieves the desired EGR delete effect without this severe consequence. This approach results in a consistent zero EGR utilization reading and only triggers a single, less critical error code (4CAE).
Step-by-Step Guide to Disconnecting the EGR Feedback Sensor
This process focuses on the electrical connector of the EGR valve motor.
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Disconnect the Connector: Carefully disconnect the electrical connector from the EGR valve motor. This connector houses the crucial feedback sensor wire we need to disconnect.
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Locate and Unlock the Terminal Restraint: Inside the connector, you’ll find a pink plastic terminal restraint. This restraint locks the individual wires in place. It needs to be shifted laterally towards pin #1 of the connector to unlock. It’s subtly visible in the image and requires minimal force to unlock. A small pick tool can be helpful.
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Remove the Feedback Sensor Wire: With the restraint unlocked, use a partially unbent paperclip to carefully insert into the small hole beside pin #5. This pin corresponds to the feedback sensor wire (black wire). Gently pull on the paperclip to extract the terminal from the connector.
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Re-lock and Reconnect: Slide the pink terminal restraint back into its locked position. This secures the remaining wires and allows the connector to be properly reattached to the EGR valve motor. Insert the connector back into the EGR motor.
Results and Considerations
This method has shown positive results, with reported fuel economy improvements from 9.2l/100km to 8.4l/100km based on user experience with an X5 35D. This translates to approximately 100km more per tank.
While effective, this electrical disconnect serves as a temporary solution. For a permanent EGR delete, removing the EGR cooler, blocking the exhaust manifold, and bypassing the coolant lines is recommended. EGR coolers are known to be prone to cracking and pose a reliability concern in the long run.
This modification is easily reversible for emissions testing. Reconnect the feedback sensor wire by reversing the steps above. Allow sufficient time for the DDE monitors to reset to a “ready” state before testing. Note: This modification has been tested on the E9x platform. It’s crucial to understand that it is NOT recommended for the F30 platform due to potential safety concerns. Always research your specific vehicle platform and engine code before implementing any modifications.
