Many owners of vehicles equipped with the 5.3L engine have encountered issues related to the Active Fuel Management (AFM), also known as Displacement on Demand (DOD) system. This system, designed to improve fuel economy, can sometimes lead to problems such as oil consumption and decreased engine performance. Fortunately, there are methods to address these issues by deleting the DOD system. This guide provides a cost-effective, do-it-yourself approach to performing a DOD delete, focusing on reprogramming the ECM via the OBD2 port and making necessary mechanical adjustments.
The original poster successfully resolved their 5.3L engine’s AFM issues by deleting the AFM program from the ECM. This process, combined with physical modifications to the lifters, led to improved engine performance and a reduction in oil consumption. Here’s how you can replicate this procedure.
Understanding the DOD Delete Process
The DOD delete involves two main components:
- ECM Reprogramming (OBD2 Tuning): This step requires a tuner to delete the AFM/DOD programming from your engine’s computer (ECM). This is often done through the OBD2 port, making it relatively accessible. By removing the software control, the system is effectively disabled.
- Mechanical Modifications: This involves addressing the lifters, which are a key part of the DOD system. In some cases, lifters can collapse or cause issues when the system is disabled via software alone.
Step-by-Step DIY DOD Delete Procedure
Based on the original poster’s experience, here’s a step-by-step guide to manually address the lifters and ensure a successful DOD delete after ECM reprogramming:
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Prepare the Lifter: Before attempting to manipulate the lifter, manually turn the engine over until the lifter you are working on is at its lowest point. This ensures there is minimal pressure on the lifter, making it easier to work with.
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Loosen the Rocker Arm: Slightly loosen the rocker arm associated with the lifter you are addressing. This provides the necessary clearance for the lifter to move freely when you attempt to reset it.
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Release the Lifter: Use a lifter release tool to pop the lifter back to its expanded position. While a specialized tool is recommended for ease of use, the original poster mentioned fabricating a tool, suggesting resourceful DIYers can find alternatives.
Alt text: Close-up of a lifter release tool being used on an engine lifter to reset it during a DOD delete procedure.
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Inspect the Push Rod: Once the lifter is expanded, remove the rocker arm and check the push rod. Roll the push rod on a flat surface to ensure it is straight and not bent. A bent push rod should be replaced.
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Lock the Lifter: After confirming the push rod is in good condition, re-insert it. Firmly tap the push rod into the lifter to ensure it locks into its expanded position. Using a plastic handled screwdriver and a hammer can help achieve this without damaging components. This step is crucial to prevent the lifter from collapsing again.
Alt text: An oil gallery plug designed to block oil flow to AFM/DOD solenoids during a DOD delete, enhancing engine reliability.
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Reassemble and Test: Reinstall the rocker arm. Critically, manually turn the engine over several revolutions to observe the lifter’s movement. Ensure it travels smoothly and correctly without any binding. This pre-start check can prevent potential engine damage if something was not correctly assembled.
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Consider Oil Plug Installation: The original poster also installed a plug to block the oil entry to the riser solenoids. This step is likely intended to further ensure the DOD system is fully disabled and to optimize oil pressure in the engine. This plug can be sourced from specialized repair shops.
Benefits and Considerations
By following these steps in conjunction with an ECM tune to delete the DOD program, you can potentially:
- Improve engine performance by ensuring all cylinders are consistently firing.
- Reduce or eliminate oil consumption issues sometimes associated with the AFM/DOD system.
- Achieve a more reliable engine operation by removing a potentially problematic system.
Tools and Resources Mentioned
The original poster referenced several helpful resources:
- Torque Specifications: Jegs – LS Engine Torque Specs – Provides essential torque specs for reassembling engine components.
- ECM Tuning Service: AMS Racing – GM AFM/DOD Delete Tuning – A service for reprogramming your ECM to delete the AFM/DOD functionality.
- Lifter Tool and Oil Plug: Crazed Performance Repair – Shop – Source for specialized tools like the lifter release tool and oil gallery plugs.
- Instructional Videos: Crazed Performance Repair – DOD/AFM Videos – Video guides for visual learners on lifter release and plug installation.
Conclusion
Deleting the DOD system on a 5.3L engine can be a worthwhile DIY project to enhance engine longevity and performance, especially if you are experiencing AFM-related issues. By combining ECM tuning via the OBD2 port with careful mechanical steps, as outlined, you can effectively disable the system. Remember to prioritize careful execution and utilize the provided resources for a successful DOD delete. Always ensure you are comfortable with engine mechanics or consult with a professional if needed.
