AFM Question

bdejonge · June 2, 2020

I just bought a 2016 Silverado 1500 LT z71 with 167,000 miles. I bought it from a dealership so it went through whatever point inspection they perform. The previous owner was the original owner and apparently drove it a ton... I would assume a lot of those miles have to be highway in order to put up 41,000 miles per year. My question is on this particular truck should I buy a Range and disable the AFM? Any other issues I should be aware of with this many miles?

I will mention that we are pulling with it at or near its capacity. I had a gooseneck hitch installed and we pull my wifes all aluminum 3 horse gooseneck with it. I don't have the weight off hand but I know it's right near the trucks capacity loaded with 3 horses. I was told that it would be a good idea to have something called a timbren added to the leafsprings. On Sunday we loaded up 2 horses and went on a trail ride. I will say the truck did not labor at all and it was a nice pull. I am wondering if you click the tow button does the AFM disable so it stays full power V8? If it is recommended that I buy a Range I will definitely do so. I just want to make the best decisions so this truck can last me a few years.

Edited June 2, 2020 by bdejonge

acinquegrana · June 2, 2020

V4 still comes on with tow/haul. Do you have a 6 speed trans? If budget is a problem one trick to disable v4 for basically any driving under 60 mph is to put the trans in manual mode and click up to M5 and leave it. This limits the trans to 5th gear and will not go into 6th and disables V4. When you go on the highway just click to 6th. V4 will then come on. I don't know how it works for the 8 speed. I have a 2016 6 speed. I did this for the last 3 yrs on my truck and it was perfect.

If budget is not a problem, get a diablo 8245 tuner. I just got mine and LOVE IT. Diasbles v4 and has tons of options to tune for MPG or more power. I had my doubts at first but after driving for about 1k miles, it is fantastic. Highly recommend. I paid 391 for it. The idea of the Range is kind of annoying that you have to leave it plugged in the obd2. When you go get an inspection and they pull it out and lose it on you, im sure you will roll your eyes lol.

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JimCost2014 · June 2, 2020

If it has made this many miles with no problems, I would not try to fix a problem that does not exist.

Maybe check with the dealership for service records just to confirm what has/not been done to it.

Would be more concerned about the service intervals on oil changes, transmission and so on.

bdejonge · June 2, 2020

I did notice that it was acting weird pulling the trailer. We were stopped and I started to accelerate and it hesitated before picking up power and taking off. I'm just assuming it had something to do with transitioning from V4 to V8 or something? I don't mind leaving the Range plugged. It sounds like the Diablo 8245 would be great but instead of spending almost $400 I could spend just $189 and still get what I need.

I was hearing that pistons or rings or seals could dry up or burn up.. Or something about burning oil. I don't know if that problem has been fixed prior to the 2016's or not. I'm just looking for opinions and information. I'm not a truck or mechanical expert. Just trying to piece together some of the details. I think it would be nicer while pulling to have V8 and not have to mess around with the V4 and lack of power. It just makes more sense to me that if you put the truck in pull mode that it would auto lock V8...........

JimCost2014 · June 2, 2020

1 minute ago, bdejonge said:

I did notice that it was acting weird pulling the trailer. We were stopped and I started to accelerate and it hesitated before picking up power and taking off. I'm just assuming it had something to do with transitioning from V4 to V8 or something? I don't mind leaving the Range plugged. It sounds like the Diablo 8245 would be great but instead of spending almost $400 I could spend just $189 and still get what I need.

I was hearing that pistons or rings or seals could dry up or burn up.. Or something about burning oil. I don't know if that problem has been fixed prior to the 2016's or not. I'm just looking for opinions and information. I'm not a truck or mechanical expert. Just trying to piece together some of the details. I think it would be nicer while pulling to have V8 and not have to mess around with the V4 and lack of power. It just makes more sense to me that if you put the truck in pull mode that it would auto lock V8...........

The AFM is pretty seamless, most times you only know if you look at the dash and see the V4 symbol.

If you are under load quite a bit, it will rarely engage the V4 mode, as a tap of the gas and you are in V8 mode.

bdejonge · June 2, 2020

35 minutes ago, acinquegrana said:

V4 still comes on with tow/haul. Do you have a 6 speed trans? If budget is a problem one trick to disable v4 for basically any driving under 60 mph is to put the trans in manual mode and click up to M5 and leave it. This limits the trans to 5th gear and will not go into 6th and disables V4. When you go on the highway just click to 6th. V4 will then come on. I don't know how it works for the 8 speed. I have a 2016 6 speed. I did this for the last 3 yrs on my truck and it was perfect.

If budget is not a problem, get a diablo 8245 tuner. I just got mine and LOVE IT. Diasbles v4 and has tons of options to tune for MPG or more power. I had my doubts at first but after driving for about 1k miles, it is fantastic. Highly recommend. I paid 391 for it. The idea of the Range is kind of annoying that you have to leave it plugged in the obd2. When you go get an inspection and they pull it out and lose it on you, im sure you will roll your eyes lol.

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Yes my truck is a 6 speed

Grumpy Bear · June 2, 2020

42 minutes ago, JimCost2014 said:

If it has made this many miles with no problems, I would not try to fix a problem that does not exist.

Maybe check with the dealership for service records just to confirm what has/not been done to it.

Would be more concerned about the service intervals on oil changes, transmission and so on.

This.

Bob2C · June 2, 2020

V4 still comes on with tow/haul. Do you have a 6 speed trans? If budget is a problem one trick to disable v4 for basically any driving under 60 mph is to put the trans in manual mode and click up to M5 and leave it. This limits the trans to 5th gear and will not go into 6th and disables V4. When you go on the highway just click to 6th. V4 will then come on. I don't know how it works for the 8 speed. I have a 2016 6 speed. I did this for the last 3 yrs on my truck and it was perfect.

If budget is not a problem, get a diablo 8245 tuner. I just got mine and LOVE IT. Diasbles v4 and has tons of options to tune for MPG or more power. I had my doubts at first but after driving for about 1k miles, it is fantastic. Highly recommend. I paid 391 for it. The idea of the Range is kind of annoying that you have to leave it plugged in the obd2. When you go get an inspection and they pull it out and lose it on you, im sure you will roll your eyes lol.

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Got the same one. I initially wanted to just raise idle to 600 because it’s was rough and turn off AFM which I did. I then began to read about tunes. I opted for the Diablew 91/93 tune. Very happy with it. The truck performs sooo much better. It’s more responsive and shifts firmer. So if you want a little more out of your vehicle get it tuned. You won’t be disappointed.

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xSHIFTxNASTYx · June 2, 2020

9 hours ago, bdejonge said:

I was hearing that pistons or rings or seals could dry up or burn up.. Or something about burning oil. I don't know if that problem has been fixed prior to the 2016's or not. I'm just looking for opinions and information. I'm not a truck or mechanical expert. Just trying to piece together some of the details. I think it would be nicer while pulling to have V8 and not have to mess around with the V4 and lack of power. It just makes more sense to me that if you put the truck in pull mode that it would auto lock V8...........

It is more or less a lifter problem as your cams are still spinning but the lifters are not engaging 4 of the cylinders which causes wear and tear on the lifters. Eventually they get worn out and then when you're back on all 8 cylinders, it can't fire the 4 cylinders that are shut off in V4 mode. Crude explanation and it may not be the best or the right explanation but it's why I'm using a Range AFM device until I can tune it out. I'd rather not have to deal with collapsed lifters if I don't have to.

bdejonge · June 2, 2020

Is a range disabler a long term solution or would I need to buy one of those $400+ tuners that have been mentioned in previous replies?

xSHIFTxNASTYx · June 2, 2020

3 minutes ago, bdejonge said:

Is a range disabler a long term solution or would I need to buy one of those $400+ tuners that have been mentioned in previous replies?

It can be a long term solution if you don't mind having a thingy plugged into your ODB port 24/7. I don't mind it as it's out of the way and I put tape over the lights so it isn't lighting up my foot well like a Christmas tree. You can just unplug it if you take it in for service and then plug it back in when they're done - no harm, no foul.

The expensive solution is to use a tuner and delete the AFM in the settings. However I'd only suggest doing that if you plan to do other things, like change your shift points, adjust your idle, modify your fuel curves, etc. You can usually pick one up in the classifieds for about $100 which is not bad considering a tuner will be triple that just to delete the AFM and then beyond depending on whether you want a BlackBear tune or if you want to buy HP credits and use HP Tuners to modify your truck.

Cheap - get a Range AFM device in classifieds for ~$100

Expensive - get a tuner and delete AFM, can cost you anywhere from ~$250-$600 depending on your wants and needs.

bdejonge · June 2, 2020

Thanks for your help

Salsa De Piña · June 2, 2020

What's your concern with AFM? If you're worried about lifter failure, a tune or Range device doesn't remove that risk. You'd need a full DOD delete (in the thousands of dollars) to be sure.

If it's been working fine for 170k miles, I wouldn't worry about it. Just change your oil.

MaverickZ71 · June 2, 2020

5 hours ago, xSHIFTxNASTYx said:

It is more or less a lifter problem as your cams are still spinning but the lifters are not engaging 4 of the cylinders which causes wear and tear on the lifters. Eventually they get worn out and then when you're back on all 8 cylinders, it can't fire the 4 cylinders that are shut off in V4 mode. Crude explanation and it may not be the best or the right explanation but it's why I'm using a Range AFM device until I can tune it out. I'd rather not have to deal with collapsed lifters if I don't have to.

Cams? Lifters not engaged but getting wear? Did I miss something here?

Agreed on the Range V8 module though. Getting one cut 3/4 of my AFM oil usage problem, with no ill effects and no loss of fuel mileage, either. Shifts better, feels better, and sounds better not going into 4 cylinder mode, too.

OP, get a Range V8 module or use a Blackbear or Diablo or Hypertech tune to turn off AFM. Be sure to use Dexos-rated (full synthetic) motor oil and a quality oil filter that still has a good flow rating, and to change your oil and filter at or before that shown by your Oil Life Indicator. Use Top Tier fuel and/or use some Chevron Techron Fuel System (not Fuel injector) cleaner (same as GM Fuel system cleaner) in your tank at each oil change. You may also want to run an oil catch can in your PCV system to help avoid fouled plugs/valves/rings. All of that is just cheap insurance, since your truck has to actually work for a living, pulling your trailer.

I use Shell Rotella Gas Truck motor oil (contains the special additive pack from their diesel oil, but for gas engines) and Wix oil filters (same as NAPA Gold or Platinum). No, I am not a Shell or Wix dealer, just someone who has had to do a lot of research and dealer visits to live with the built-in AFM problems on a meticulously maintained Silverado daily driver.

Edited June 2, 2020 by MaverickZ71

xSHIFTxNASTYx · June 2, 2020

4 minutes ago, MaverickZ71 said:

Cams? Lifters not engaged but getting wear? Did I miss something here? Agreed on the Range V8 module though, it's cheap insurance.

Okay, so.....I'm not the best car guy and not the best at explaining things I am not an expert at, but here goes (funny, I work in an engine plant so I should know this).

Your cams turn, and those cams have these lifters on them, these lifters actuate intake and exhaust valves on your cylinder head. When you're running in V8 mode, all valves are being actuated, opening and closing, no problem there. When you're running in V4 mode, with AFM active, not all of the valves are opening and closing. However, your cams are still turning and your lifters are being beat to ****** on the valves that aren't being actuated. Over time these lifters can wear and eventually you get what is called a "collapsed lifter". The wear and tear is so great that the lifters cannot actuate the valves they're supposed to open and close. This is lifter failure. It can be prolonged by using a Range AFM device or tuning out the AFM setting in your truck. This isn't an end-all-be-all fix but if it helps, you bet your butt I'm goind to do everything I can to prevent lifter failure.

Hope that makes some sense.