Displacement on Demand (DOD) is a General Motors (GM) technology that improves your vehicle’s fuel economy by shutting down half of the engine cylinders under light-load conditions.
It’ll then revert to full engine performance under heavy loads, improving gas mileage by 5-7%.
However, it has some significant shortcomings that may outweigh its advantages, forcing some people to do a DOD delete. What is it?
DOD delete is a complete removal of the Active Fuel Management (AFM) system to avoid long-term problems, including loss of power and high oil consumption.
To perform a DOD delete, you’ll have to install new lifters, valve springs, DOD delete plugs, and push rods, among other items.
In today’s article, we’re looking at the process of doing a DOD delete and its pros and cons.
Advantages of DOD Delete
General DOD lifters tend to get stuck or fail on higher mileage cars. As a result, most drivers perform a DOD delete to avoid the costly repairs associated with the problem.
But that is not all. Let’s look at the advantages of a DOD delete.
DOD Benefits Become Less With Higher Mileage
As we’ve seen, the benefits of DOD are more apparent in newer engines with lower mileage. If you have an older car or would want to install performance upgrades, it’s better if you do a DOD delete.
Less Oil and Maintenance Costs
DOD is very oil intensive, and you’ll spend more money refilling the oil tank if your vehicle has an active DOD.
Deleting DOD and replacing its filters with standard manufacturer-recommended ones will lower overall oil and maintenance costs.
Better Engine Performance
DOD delete is a practical solution for LS engines as it reduces the money spent on preventive maintenance. Also, it allows your engine to run on all cylinders, delivering more torque and power at all times.
Less Engine Jerk and Hesitation
Installing DOD may cause your car to hesitate and jerk when accelerating. To some, this can be very irritating and a problem that outweighs the improved fuel economy that comes with the DOD.
To improve the overall safety of the driver and other road users, you should delete the DOD if you experience jerks when accelerating.
Better Exhaust Sound
General Motors (GM) vehicles equipped with the DOD may have an annoying four-cylinder exhaust noise during low power modes. Removing the DOD will surely improve the exhaust sound quality.
Common Problems After DOD Delete
DOD’s main purpose in a gasoline engine is to reduce the number of cylinders burning fuel under light engine loads to improve fuel economy. If you delete the DOD, your car may experience reduced fuel economy and increased emission levels, among other problems.
Let’s look at these common problems:
Reduced Fuel Economy
Deleting DOD removes your car’s control over the cylinders it requires under varying load conditions.
As a result, it will revert your car’s gas mileage to the original values, as all cylinders will run at all times.
Increased Emissions
Deleting the DOD results in increased emissions. A higher number of engine cylinders running at a time burns more fuel, resulting in greater emissions.
Increase in Engine Noise and Vibration
Some DOD-equipped vehicles may experience slight vibration in the steering wheel, the floor pan, or the accelerator pedal. This is normal, and you shouldn’t attempt any repairs on your vehicle.
However, you’ll experience a noticeable increase in these vibrations once you delete the DOD. These vibrations will strain your exhaust, ultimately causing it to fail.
Over time, the vibrations may reach the engine if left unrepaired, causing some damage.
Engine Knocks
DOD deletes may cause the engine to run hotter, leading to a build-up of carbon deposits on the lifters or cylinder walls.
When the deposit build-up reaches a certain threshold, the engine pistons may seize, leading to engine knocks.
More Engine Wear
DOD uses a lot of oil to function as required and prevent your car from stalling. If left unchecked, it will consume a significant fraction of engine oil, reducing pressure, and failing some components.
Loss of Power and Hesitation
Deleting the DOD forces the engine to work harder than required, as it will be utilizing all cylinders even when you don’t need maximum power.
Over time, the engine will deteriorate, lowering its overall capacity and resulting in a noticeable loss of power and occasional hesitation.
How To Delete or Disable DOD
If you don’t like how your DOD works, the two options are simply disabling it or deleting the whole system.
If you want to disable it, you will have to restrict the operation of its parts, including the Lifter Oil Manifold Assembly (LOMA) or valley cover, high-volume oil pump, special oil pressure relief valve, and lifters.
And the best way around this is to replace the parts with standard non-AFM parts. But it isn’t as straightforward as it may seem.
To do a successful disabling requires the assistance of a licensed mechanic, who’ll also reconfigure the engine ECU never to activate the AFM.
How to Disable the DOD
It’s very difficult and complicated to disable the DOD by reprogramming the ECU, due to a set of unique protection codes that safeguard the system’s electronics.
To work around this, most aftermarket programmers use a passive DOD disabler that uses a port injection to trick the ECU into thinking that all engine cylinders are firing at that time.
In effect, it prevents the engine from switching to the four-cylinder mode, hence staying in V8 mode.
One popular option is the Range Technology disabler, which doesn’t reprogram your car’s computers. We don’t recommend reprogramming the ECU, as doing so may void the engine warranty.
Additionally, only use a disabler device if the valve train is working correctly.
Next, replace the high-volume oil pump with a standard one, as you won’t need the high oil levels within your engine.
Injection of excess oil will ultimately burn the cylinder walls in high-rpm engines.
After disabling the DOD, ensure to tune your vehicle so that it doesn’t revert to 4-cylinder mode.
How to Delete the DOD
If you’re tired of having the DOD, you can opt to eliminate the system from your vehicle.
However, doing so is labor intensive, costly, and complicated as it requires a custom tune or disabler device to be successful.
Consequently, we only recommend deleting the DOD when you have no other option.
Here’s how to do so:
- Replace your DOD camshaft with a non-DOD camshaft
- Replace the AFM lifters with standard lifters
- Swap out the valley cover with a non-AFM valley cover
- Deactivate the AFM system
- Plug the pressure relief valve (PRV) into the oil pan
- Install a standard oil pump
Final Remarks on the DOD Delete Function
AFM systems are beneficial and were designed to improve fuel economy and reduce emissions in large-capacity GM engines.
Over time, however, they underperform, become problematic, and remain useful only in newer engines with lower mileages, forcing many drivers to deactivate or delete the systems.
Remember, only delete the DOD if you have failed lifters, as the process is labor-intensive and costly. Disabling the system is a better option as it allows you to reinstall it without spending much money.
Of importance, however, is that you should replace the high-volume oil pump in both cases.
Finally, a major downside of disabling the DOD is a decrease in your vehicle’s fuel economy by 5 to 15%. But, the money saved in avoiding expensive DOD repairs outweighs the extra fuel costs.
