Problems After AFM Delete (Fixed)

Are you planning to disable or delete active fuel management (AFM) but worried about the post-delete effect? It’s smart thinking. Many GM, Chevy or other car owners who have V6 and V8 engines experience various problems after deleting AFM. So, it’s wise to decide by measuring pre and post-effect.

Common problems after AFM delete occurs are the engine’s rough idle, flashing Check Engine Light, excessive noise and vibration, and reduced fuel economy. It also increases emissions and prevents the car from starting. But if you are experiencing more severe issues with the system, you can easily disable and delete AFM in your home garage.

Common Problems After AFM Delete

Active fuel management (AFM) was intended to improve gas mileage by turning off half cylinders under light load conditions. It is also known as cylinder deactivation and displacement on demand ( DoD) on some models. It’s believed that AFM provides 5% to 7% more fuel efficiency.

However, in practice, it doesn’t make a huge difference in gas mileage. Instead, it causes faster wear and tear on the engine, reduce the engine’s performance, and make the car less powerful.

So many owners of Chevy Silverado or cars with AFM system decide to disable or delete the AFM which brings some negative effects. Below are some common problems that you may experience after deleting the AFM system:

Rough Idle

Your car can cause rough idle after deleting AFM. At a time, the car can misfire every 4 to 5 seconds and drop RPM before recovering. It can happen if AFM is disabled when the car has low oil pressure or a fault in the cylinder deactivation system. The symptom includes engine vibration, activates check engine light, and rough run or stalled engine.

To fix this problem, firstly scan the car. If the car shows codes like P3400, P3425, or P3441, bring the car to an expert mechanic. He will inspect various engine components, related wiring harnesses, and connectors and test certain cylinders to determine and solve the actual problem.

Car Engine Won’t Start

Your car won’t start after deleting AFM. It may sound like something trying to work but the engine isn’t turning over.  It can happen if something is disconnected or displaced before or after deleting the AFM.

So, check the engine plugs, plug wires, vacuum lines, and MAF sensor and make sure all are connected properly. If everything is ok, check the fuel injector as it may not get a signal. The injector has two wires and one wire remains constant at 12V with the key in the run position.

The other wire pulse the negative signal to open the injector during cranking and running. Connect a test light between the wires and crank the engine.  The test light should light up if the injector receives the signal. If not, repair or replace the injector or PCM with the aid of an expert mechanic.

Flashing CEL

Some car owner particularly those who have a 2010 LS motor gets flashing CEL and service StabiliTrak message after deleting AFM or DOD. It happens mostly after idling the car for more than a minute. They also experience it hard to shift from 1st gear to 2nd gear and misfire on the DOD cylinder as well as the P0300 error code.

If you are facing the same issue, check the throttle body motor as its long thread can become damaged. You may need to replace the TB to solve this issue. You can also program ECM to disappear the P0300 code.

Reduced Fuel Economy

The AFM system is particularly designed to improve fuel consumption. So after deleting the AFM, you may experience reduced fuel economy. It happens because the engine can’t run on fewer cylinders particularly when full power isn’t essential. So the engine needs to work harder which results in more fuel consumption.

Increased Emissions

You may also experience increased emissions after disabling AFM. Since the engine consumes more fuel to work harder after deleting AFM, it releases more emissions than usual.

Excess Noise and Vibration

Hearing excessive noise and vibration from the engine is also a common problem that you may experience after deleting AFM. AFM deletion can also strain exhaust over time.

How To Disable AFM Without A Tune

It needs to reprogram or trick the ECU into V8 mode to disable the AFM. So you have to install an AFM disabler to disable the AFM on your Chevy, GM, or other car. The AFM disabler needs to connect to the OBD-II port that is placed under the dashboard.

This electronic device prevents the computer to activate the four-cylinder mode. If you want to disable AFM for free in the home garage, this is your most effective and simplest method. The AFM disabler also helps improve the exhaust sound. If you want to turn the AFM system on again, simply remove the AFM disabler from the OBD-II port.

Things to Remember While Installing AFM Disabler

You must make sure the valve train of your vehicle is in good condition before trying to disable AFM.  Another important thing to remember is that a car with AFM has a high-volume oil pump. After disabling the AFM, the engine doesn’t require extra oil.

Hence it pushes out the excess oil from the pressure relief valve to the oil pan. During pushing the oil, some oil sprayed on the cylinder walls bottom. It can cause oil burning particularly in a high RPM engine. To avoid this issue, replace the high-volume oil pump with a standard one.

Reprogramming the ECU can also void the engine warranty. So if you want to disable AFM without reprogramming the ECU and void the warranty, opt for a Range Technology Disabler.

How To Delete AFM?

If you want to delete the AFM permanently from your vehicle, install an AFM Delete kit on it. It’s a preferable method to apply when the AFM fails or during performing upgrades. Installing the AFM delete kit also replaces the AFM parts with standard components.

Before installing the AFM delete kit, upgrade your vehicle with a non-AFM camshaft. This is because the four AFM cylinder’s cam lobes are ground differently. After deleting the AFM, the engine will have 25 pounds lighter compression which can result in misfire code.

Then use custom tuning or a computer programmer to deactivate the AFM system. Once done, plug and connect the pressure relief valve into the oil pan and switch to a standard volume oil pump. Deleting AFM is also a bit tiresome process as it needs to replace the entire AFM components.

Below is some action that needs to perform to delete the AFM permanently:

• Replacing the camshaft with a non-AFM camshaft.
• Using standard lifters instead of AFM lifters.
• Removing the valley cover and using non-AFM valley cover.
• Deleting the AFM system.
• Connecting the pressure relief valve in the oil pan.
• Replacing the high-volume oil pump with a standard one.

Is AFM Deletion Worth it?

A vehicle owner who doesn’t want to spend thousands on AFM-related repairs mostly decides to disable or delete the AFM system. This not only prevents tiresome maintenance but also provides better exhaust noise and activates the V8 mode all the time.

Deleting the AFM system also helps save lifters and oil consumption and provides a better pedal response. However, it can only delay the lifter failure instead of preventing it.

You can also reduce exhaust emissions by deleting the AFM and enjoy maximum performance out of the engine.  Even it is very easier to delete the AFM system as it only requires a few hours and some skills.

FAQs on Problems After AFM Delete

Final Words

Active fuel management has both pros and cons. No matter you use the AFM or delete it, your car’s engine will experience some negative effects in both cases. While using AFM can cause the engine to wear and tear faster, deleting the system cause rough idle, irritating noise, and increased fuel consumption.

Hope you can measure the risk of deleting the AFM system and decide whether you should let it work or delete it.