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DOD Delete OBD2: A DIY Guide to Disabling AFM on 5.3L Engines

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Are you experiencing issues with your 5.3L engine, such as excessive oil consumption or decreased performance? You might be dealing with Active Fuel Management (AFM), also known as Displacement on Demand (DOD). This system, designed to improve fuel economy, can sometimes lead to problems. Fortunately, there’s a solution: deleting the DOD system. This guide will walk you through a DIY approach to disable AFM/DOD on your 5.3L engine, focusing on a cost-effective method using an OBD2 port and ECM reprogramming.

Understanding DOD/AFM and Why Delete It

General Motors’ Active Fuel Management (AFM), or Displacement on Demand (DOD), is a technology that deactivates cylinders in certain driving conditions to enhance fuel efficiency. While beneficial in theory, in practice, it has been linked to several issues, particularly in the 5.3L engines. These problems include:

  • Increased Oil Consumption: AFM can cause oil to be drawn into the combustion chamber, leading to higher oil consumption and potentially engine damage over time.
  • Lifter Failure: The lifters in AFM-equipped engines are more complex and prone to failure. This can result in noisy operation, misfires, and significant engine problems.
  • Reduced Performance: Some drivers feel a slight hesitation or lag in performance as the engine switches between V8 and V4 modes.

Deleting the DOD/AFM system can address these issues, leading to a more reliable and responsive engine. One popular method involves reprogramming your engine’s computer (ECM) to eliminate the AFM functionality. This, combined with mechanical steps to ensure the deactivated cylinders operate correctly, can effectively disable DOD/AFM.

DIY DOD Delete Procedure: A Step-by-Step Guide

This guide outlines a DIY procedure to disable AFM/DOD, focusing on the ECM reprogramming and a specific method for managing the lifters. Please note: This procedure involves modifying your vehicle’s ECM and requires mechanical knowledge. If you are not comfortable with these steps, it’s recommended to seek professional assistance.

Tools and Materials You’ll Need

Before starting, gather the necessary tools and materials:

  • ECM Tuning Service: You’ll need a service to delete the AFM program from your ECM. A reputable online service like the one from AMS Racing offers this service. This typically involves sending in your ECM for reprogramming or receiving a tuned ECM.
  • Lifter Release Tool: To ensure the AFM lifters are properly functioning after the ECM reprogramming, a lifter release tool is highly recommended. While you can attempt to fabricate one, purchasing a tool like the one from Crazed Performance Repair (CPR) will save time and hassle.
  • Oil Gallery Plug: This plug is used to block off the oil supply to the AFM solenoid riser. This is also available at Crazed Performance Repair (CPR).
  • Basic Mechanic Tools: Wrenches, sockets, screwdrivers, hammer, etc.
  • Torque Wrench: Essential for properly tightening bolts to specification. Refer to torque specs from resources like Jegs Torque Specs.

Step-by-Step Instructions

Follow these steps carefully to perform the DOD delete:

  1. ECM Reprogramming:

    • Remove your ECM and send it to the tuning service you’ve chosen (e.g., AMS Racing). Follow their instructions for removal and shipping.
    • Alternatively, if the service provides a pre-tuned ECM, you will receive the new ECM to install.
    • Once you receive your reprogrammed ECM, install it back into your vehicle.

  2. Lifter Management:

    • Locate AFM Lifters: Identify the AFM lifters on your 5.3L engine. These are typically located on cylinders 1 and 7 (check your specific engine configuration).
    • Position Lifter at Lowest Point: Manually rotate the engine by hand (using a wrench on the crankshaft pulley) until the lifter you are working on is at its lowest point in its cycle. This ensures minimal pressure when releasing the lifter.
    • Loosen Rocker Arm: Slightly loosen the rocker arm for the valve associated with the lifter you are working on. This provides space for the lifter to expand freely.
    • Release the Lifter: Use the lifter release tool to gently pop the lifter back to its expanded position. If you’re using the CPR tool, follow their instructions. If fabricating your own, be extremely careful not to damage the lifter.
    • Check Push Rod: Once the lifter is expanded, remove the rocker arm and inspect the pushrod. Roll the pushrod on a flat surface to check for any bending. Replace it if it’s bent.
    • Lock Lifter (If Necessary): In some cases, the lifter might expand past its lock position. To ensure it’s locked, gently tap the pushrod into the lifter using a plastic handled screwdriver and a hammer. A light tap is sufficient.
    • Reinstall Rocker Arm: Reinstall the rocker arm to the correct torque specification.
    • Repeat for Other AFM Lifters: Repeat steps 2.b through 2.g for all other AFM lifters.

  3. Install Oil Gallery Plug:

    • Locate the oil entry point for the AFM solenoid riser on your engine block. (Refer to videos from Crazed Performance Repair (CPR) for visual guidance).
    • Install the oil gallery plug to block off the oil supply to the AFM system.

  4. Engine Rotation Test:

    • Manually rotate the engine through several revolutions by hand. This step is crucial to ensure all lifters are moving freely and there is no binding or interference. Pay attention to any unusual noises or resistance.

  5. Start Engine and Verify:

    • Start your engine and listen for smooth operation. You should notice improved engine responsiveness and potentially a reduction in oil consumption over time.

This image shows engine components relevant to the DOD delete process, including lifters and valve train.

Benefits of DOD Delete

By performing a DOD delete, you can expect several benefits:

  • Reduced Oil Consumption: Eliminating AFM often significantly reduces or eliminates excessive oil consumption issues.
  • Increased Engine Reliability: By removing the complex AFM lifters and system, you reduce potential points of failure, leading to a more reliable engine.
  • Improved Performance and Responsiveness: The engine operates consistently in V8 mode, providing more predictable and responsive performance.
  • Cost-Effective Solution: Compared to expensive repairs or engine replacements due to AFM-related failures, a DOD delete is a relatively affordable solution, especially when done DIY.

Conclusion

Disabling DOD/AFM on your 5.3L engine through ECM reprogramming and mechanical adjustments can be a worthwhile DIY project to address common issues like oil consumption and lifter problems. By following these steps and utilizing the recommended resources, you can effectively eliminate the AFM system and enjoy a more reliable and better-performing engine. Remember to always prioritize safety and consult professional resources if you are unsure about any part of this procedure.

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