New member here trying to decide if I should delete the AFM or not. Engine is currently apart.

[JJ1971]

Hello I am a new member here and I have not owned a GM Vehcile in about 20 years. I just acquired a 2018 Denali with multiple issues with the AFM system. I pulled out 2 bent push rods, 1 lifter that came out in 3 pieces, The cam shaft has enough wear that it's getting replaced. I crunched the numbers using all GM OEM parts to repair the system which includes a new VLOM vs buying a delete kit. At this time I was considering the AMS Racing kit which includes a Diablo hand held programmer. The price to either repair vs delete are about 150.00 only in total.
I am curious if GM has updated the AFM/DOD parts since 2018 and if they are any more reliable. I am big on keeping things OEM but with this AFM system having so many issues I am considering deleting. I understand it would lose about 8% MPG on the highway or under light load. Not sure if the fuel savings over time would be worth it if this AFM system fails again. How has the reliability been after replacing the damaged AFM parts over time. How many miles have people been getting or is this simply still a gamble? If I do delete what is the opinion on the Diablo tuner vs paying someone or purchasing HP tuners setup? I need to make this decision very soon as this Yukon is tying up my bay and I need to order parts. Thank you.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

I believe that the overwhelming opinion of members on this Forum is to delete the AFM, as it is a known point of failure on these engines. Specific delete kits are offered by many vendors, and popular vendors for these kits, along with plenty of technical support as needed are Texas Speed and Summit Racing.

 

[intergalactron]

Do an AFM delete and don't look back. My experience with a 2013 Silverado (full AFM delete) and a 2020 Tahoe (AFM turned off in ECU) is that you won't notice any change in mileage.

On both trucks I used a Superchips tuner with good results. They come with a few canned programs for slightly improved performance, shifts, etc.

The basic tuners work fine if you stick with a stock cam. If you go with something pepped up, you'll need a custom tune.

 

[Coveman]

delete!

 

[JJ1971]

Thank you! I ordered a full delete kit today from AMS Racing along with about 100 other parts from the dealer. I own a Jeep shop and I have been dealing with Chrysler parts all these years. I cannot believe how inexpensive GM parts are in comparison I am literally blown away! Someone asked for pictures it really looks like any other one but here are some. It broke down in California and I paid to tow it back to Maryland since the price was right. This is for my wife to replace her Minivan so she can drive something and have pride and actually move out of its own way.

 

[89Suburban]

Thank you! I ordered a full delete kit today from AMS Racing along with about 100 other parts from the dealer. I own a Jeep shop and I have been dealing with Chrysler parts all these years. I cannot believe how inexpensive GM parts are in comparison I am literally blown away! Someone asked for pictures it really looks like any other one but here are some. It broke down in California and I paid to tow it back to Maryland since the price was right. This is for my wife to replace her Minivan so she can drive something and have pride and actually move out of its own way.

While you are in there and have the room to get to them, replace the heater hose firewall Tee's with metal ones.

 

[West 1]

I have repaired many AFM engines, only done the delete 2 times. The best way to do the delete is to go into the GM Computer, I believe the Tech 2 allows you to switch the AFM system off. It asks if the vehicle has AFM, you answer yes or no. When you answer No it is gone from the software. A smog shop check no longer see’s that the vehicle had AFM from the factory. It has been a few years since I did the last delete but that was a better option than using tuners to do the same.

 

[89Suburban]

I have repaired many AFM engines, only done the delete 2 times. The best way to do the delete is to go into the GM Computer, I believe the Tech 2 allows you to switch the AFM system off. It asks if the vehicle has AFM, you answer yes or no. When you answer No it is gone from the software. A smog shop check no longer see’s that the vehicle had AFM from the factory. It has been a few years since I did the last delete but that was a better option than using tuners to do the same.

I have not heard of this procedure?

 

[Marky Dissod]

I have repaired many AFM engines, only done the disable 2 times.
The best way to do the disable is to go into the GM Computer, I believe the Tech 2 allows you to switch the AFM system off.
It asks if the vehicle has AFM, you answer 'yes' or 'no'. When you answer 'No', it is gone from the software.
A smog shop check no longer sees that the vehicle had AFM from the factory.

It has been a few years since I did the last disable but that was a better option than using tuners to do the same.

Fixed it for you. The above refers to disabling / turning off the feature.
Think very early L92 - they came with the hardware, but the feature was DISABLED,
before GM DELETED all Enginre Half@$$ parts from the L92 & L9H.
'Delete' refers to PHYSICALLY REMOVING the Engine Half@$$ hardware.

JJ1971, delete whatever cylinder deactivation hardware you might have.
Don't forget to disable the feature in the tune as well.
If you experience an 8% MpG penalty, you used to drive like a hypermiler.

 

[2017sltXL]

Thank you! I ordered a full delete kit today from AMS Racing along with about 100 other parts from the dealer. I own a Jeep shop and I have been dealing with Chrysler parts all these years. I cannot believe how inexpensive GM parts are in comparison I am literally blown away! Someone asked for pictures it really looks like any other one but here are some. It broke down in California and I paid to tow it back to Maryland since the price was right. This is for my wife to replace her Minivan so she can drive something and have pride and actually move out of its own way.

Do you plan to freshen up the heads?
Money well spent if you are in it that far.

 

[West 1]

I agree with what 2 said, I have fixed 2 6.2L engines because a valve seat dropped out of the head and caused a piston to be broken. Rebuilt heads with new exhaust valve seats is a good idea. I was trying to remember what program allowed the delete I did. I did have to pay $125 to GM to use the program for the Vin Codes and the program ran through a windows based laptop.. I know one was a 2007 5.3L, I thought the second was a 2010 5.3L engine? I would have to go back and find the sheets to verify. In California I was told by a buddy that runs a very busy shop the the Smog Test locations were getting new technology that can verify if the computer has had changes. For this reason I stopped doing deletes and started installing all new AFM parts in any failure I fixed. This goes back to 2021/2022.

 

[JJ1971]

I was not planning to do anything to the heads other than cleaning them up before reassembly. It has 120k miles on it. Our only local machine shop would take about a month to do this. I am getting my advise from a master gm tech on what I should be replacing. He has. Not mentioned anything regarding the heads. He is advising I replace the oil pump and drop the pan vs not taking the pan off which means the diff and rack need to come out. There are videos that I watched where people have been able to replace the cam without removing the oil pump. Someone mentioned metal coolant t’s please share a link thank you.

 

[Geotrash]

I have repaired many AFM engines, only done the delete 2 times. The best way to do the delete is to go into the GM Computer, I believe the Tech 2 allows you to switch the AFM system off. It asks if the vehicle has AFM, you answer yes or no. When you answer No it is gone from the software. A smog shop check no longer see’s that the vehicle had AFM from the factory. It has been a few years since I did the last delete but that was a better option than using tuners to do the same.

I have a Tech 2, a J2534 pass-thru scanner for ACDelco TDS, and an HP Tuners MPVI2. Of the three, the MPVI2 is the only one I'm aware of that can turn off AFM. In all of my years participating here and owning 4 GM long-body SUVs, this is the first time anyone has said that it can be done with a Tech 2. Also, the Tech 2 does not work on this generation of GM SUV. Compatibility ended with the 2014 model year. @swathdiver

 

[Geotrash]

I was not planning to do anything to the heads other than cleaning them up before reassembly. It has 120k miles on it. Our only local machine shop would take about a month to do this. I am getting my advise from a master gm tech on what I should be replacing. He has. Not mentioned anything regarding the heads. He is advising I replace the oil pump and drop the pan vs not taking the pan off which means the diff and rack need to come out. There are videos that I watched where people have been able to replace the cam without removing the oil pump. Someone mentioned metal coolant t’s please share a link thank you.

Just a few things that might be helpful:

Dropping a valve seat on these does happen but it's pretty rare and usually only happens as a result of overheating. The plastic coolant tees at the firewall are notorious for disintegrating after a decade or so, and when they go, it's usually on the highway or sometime when the engine is putting out a lot of power and generating heat and pressure in the system, so the instantaneous loss of coolant causes the engine to overheat almost immediately. Some have said that that they dropped a valve seat when they pulled off the highway at a rest area while towing and immediately shut the engine down, resulting in a temperature spike in the heads. Others have said that failing to get all of the air out of the cooling system after a flush caused hot spots in the heads. Still others have had it happen spontaneously. But either way, preventing any overheating on LS/LT heads is your best risk mitigation strategy.

Since you have time constraints, I would just take a good look at all of the valve seats and make sure they're well-seated, visually. I would also take the time to replace the valve stem seals. It'll take you an hour to do them all, and it's also a good time to take the valves out and get a better look at all of the seats. Fel-Pro makes great replacement seals for these.

It's possible to get the pan off without pulling the diff all the way out. Just remove the passenger side mount, loosen the drivers side mount, and let it hang. Same with the steering rack - just remove the mounting bolts and let it hang from the tie rods.

Replacing the oil pump is a good idea, but if you don't do that, at the very least replace the o-ring on the pickup tube because they get hard and brittle over time and start sucking air, causing oil pressure loss, or worse. The problem is though that you have to drop the pan to do that, so you might as well replace the pump at that point.

Connector 1: https://a.co/d/25KBzRr
Connector 2: https://a.co/d/ibvXOfI
Connector 3: https://a.co/d/gXM5ON9

They go here (photo is from a 2018 Suburban 3500 HD, but the Yukon Denali 1500 will be the same):

 

[West 1]

It was a couple years ago, my son actually did the AFM shut off, I was busy on another job. I know I paid for a license to do the job through GM, if that was not Tech 2, my mistake. I will ask my son what program it was. I have a Launch X431V+ and it could not do it although it does allow programing some of the modules.

I did not realize this engine only has 120,000 miles on it. At that mileage I probably would run those heads without a rebuild. Any idea why you had cam failure at that low mileage?

 

[JJ1971]

Just a few things that might be helpful:

Dropping a valve seat on these does happen but it's pretty rare and usually only happens as a result of overheating. The plastic coolant tees at the firewall are notorious for disintegrating after a decade or so, and when they go, it's usually on the highway or sometime when the engine is putting out a lot of power and generating heat and pressure in the system, so the instantaneous loss of coolant causes the engine to overheat almost immediately. Some have said that that they dropped a valve seat when they pulled off the highway at a rest area while towing and immediately shut the engine down, resulting in a temperature spike in the heads. Others have said that failing to get all of the air out of the cooling system after a flush caused hot spots in the heads. Still others have had it happen spontaneously. But either way, preventing any overheating on LS/LT heads is your best risk mitigation strategy.

Since you have time constraints, I would just take a good look at all of the valve seats and make sure they're well-seated, visually. I would also take the time to replace the valve stem seals. It'll take you an hour to do them all, and it's also a good time to take the valves out and get a better look at all of the seats. Fel-Pro makes great replacement seals for these.

It's possible to get the pan off without pulling the diff all the way out. Just remove the passenger side mount, loosen the drivers side mount, and let it hang. Same with the steering rack - just remove the mounting bolts and let it hang from the tie rods.

Replacing the oil pump is a good idea, but if you don't do that, at the very least replace the o-ring on the pickup tube because they get hard and brittle over time and start sucking air, causing oil pressure loss, or worse. The problem is though that you have to drop the pan to do that, so you might as well replace the pump at that point.

Connector 1: https://a.co/d/25KBzRr
Connector 2: https://a.co/d/ibvXOfI
Connector 3: https://a.co/d/gXM5ON9

They go here (photo is from a 2018 Suburban 3500 HD, but the Yukon Denali 1500 will be the same):

View attachment 458742

Thank you for posting that information. I added them to my wish list to research later today or tomorrow. I am not a fan of plastic parts. How have the Dorman parts been holding up over time? Today I pulled the diff out along with the oil pan and oil pump , front cover. I am waiting on my delete kit to arrive. my only real constraint is I am tying up one of our bays.

 

[JJ1971]

It was a couple years ago, my son actually did the AFM shut off, I was busy on another job. I know I paid for a license to do the job through GM, if that was not Tech 2, my mistake. I will ask my son what program it was. I have a Launch X431V+ and it could not do it although it does allow programing some of the modules.

I did not realize this engine only has 120,000 miles on it. At that mileage I probably would run those heads without a rebuild. Any idea why you had cam failure at that low mileage?

This was one of my good customers Vehcile. He lives here in MD but lives in CA during the winter months. Cyl number 4 bent a push rod and the roller on the lifter did some damage to the cam shaft lobe. The lifter also came apart in 3 pieces when I removed it. It melted the catalytic converter to the point where the engine would not even run. I found another bent push rod on #1. once I unbolted the exhaust it fired right up and I was able to hear the ticking noise over the loud exhaust. Because the AFM delete requires a new cam shaft and lifters I had to make the choice to repair or delete. Some videos I watched claimed about 8% MPG loss at highway speeds where the engine goes into 4 cylinder mode. is 8% not accurate? someone mentioned this earlier in this thread. I am more concerned with reliability over MPG. I do not want to do the job again. the AMS racing kit includes a Diablo handheld programer which I am familiar with as I have installed super chargers on Jeeps and that is what they often use. It's not bad and it can do some other features. I did not want to invest in HP tuners as they charge for tokens or something like that each time you program a vehicle.

 

[Geotrash]

Thank you for posting that information. I added them to my wish list to research later today or tomorrow. I am not a fan of plastic parts. How have the Dorman parts been holding up over time? Today I pulled the diff out along with the oil pan and oil pump , front cover. I am waiting on my delete kit to arrive. my only real constraint is I am tying up one of our bays.

People used to have problems with the Dorman tees not lasting as long, but I haven't heard of any problems with them in the last several years. FWIW, I've been running a set of Dorman plastic tees on my 2012 since early 2021 and no issues over lots of heavy towing miles. I'll replace them with the aluminum versions in probably 2028 or so.

 

[RET423]

The answer is always "Delete the AFM"

 

[hatinthering]

Having just completed mine over the past weekend (with 200K miles, lifter failure), I can't imagine not doing the delete if you're already disassembled. Just do it and never worry about it again.