Jump to content

2021 Silverado DFM/AFM

PClancey
 Share

Recommended Posts

shanemoon Enthusiast

shanemoon

Posted
Posted
On 6/6/2021 at 1:44 PM, EricTheRed said:

Can the dealership do a DFM delete for those of us who don’t want the added noises and shuttering of this “seamless” system? 

???

DFM is not noticeable at all. AFM maybe, but not DFM. You'll never know when it's doing it.

You talking about auto start/stop?

  • Like 1
  • Haha 1
EricTheRed Enthusiast

EricTheRed

Posted
Posted
On 1/5/2022 at 7:18 PM, shanemoon said:

???

DFM is not noticeable at all. AFM maybe, but not DFM. You'll never know when it's doing it.

You talking about auto start/stop?


I can’t tell if you’re joking or just can’t hear your engine well enough, but either way thanks for the laugh.

voided3 Enthusiast

voided3

Posted
Posted
12 hours ago, EricTheRed said:


I can’t tell if you’re joking or just can’t hear your engine well enough, but either way thanks for the laugh.

Agreed, cruising at specifically 31 MPH our truck sounds like a helicopter with DFM active and it feels like a parachute is chained to the hitch when it activates cruising at 55-65 MPH, plus all of the vibration at any speed when it's active. Disabling the system by driving in L7 is the only tolerable way for me to drive it.

shanemoon Enthusiast

shanemoon

Posted
Posted (edited)
14 hours ago, voided3 said:

Agreed, cruising at specifically 31 MPH our truck sounds like a helicopter with DFM active and it feels like a parachute is chained to the hitch when it activates cruising at 55-65 MPH, plus all of the vibration at any speed when it's active. Disabling the system by driving in L7 is the only tolerable way for me to drive it.

 

On 1/7/2022 at 6:47 PM, EricTheRed said:


I can’t tell if you’re joking or just can’t hear your engine well enough, but either way thanks for the laugh.

Dynamic and individualized cylinder deactivation is not perceivable on any vehicle that has it. Or at least not the 20-30 I’ve driven that have it. Most other car reviewers/journalists would say the same. 
AFM and similar technologies from other manufacturers on the other hand, is very noticeable.


I cannot feel or hear DFM on my Silverado even if I try. And I work on cars for a living.
There are plenty of other forum posts that also echo is…that DFM is seamless and it was a huge improvement from AFM where you could feel and hear it every time. 

Either you guys just have a bad batch, or you actually have AFM trucks and you think you have DFM. Might want to check your RPO codes. L84 is DFM. L83 is AFM. 

Edited by shanemoon
  • Like 1
BossTaco2020 Enthusiast

BossTaco2020

Posted
Posted
On 1/8/2022 at 10:53 PM, shanemoon said:

 

Dynamic and individualized cylinder deactivation is not perceivable on any vehicle that has it. Or at least not the 20-30 I’ve driven that have it. Most other car reviewers/journalists would say the same. 
AFM and similar technologies from other manufacturers on the other hand, is very noticeable.


I cannot feel or hear DFM on my Silverado even if I try. And I work on cars for a living.
There are plenty of other forum posts that also echo is…that DFM is seamless and it was a huge improvement from AFM where you could feel and hear it every time. 

Either you guys just have a bad batch, or you actually have AFM trucks and you think you have DFM. Might want to check your RPO codes. L84 is DFM. L83 is AFM. 

Exactly! I can't tell when DFM activates on my 5.3 w/10spd trans. However I do feel vibration, but that's from the crappy DuraTracs that I can't wait to get rid of. I think people just want to hate on any new technology and then there's the "I pAiD fOr A v8 and mUh FrEeDuMz!!!" people...

  • Like 1
KARNUT Senior Enthusiast

KARNUT

Posted
Posted
33 minutes ago, BossTaco2020 said:

Exactly! I can't tell when DFM activates on my 5.3 w/10spd trans. However I do feel vibration, but that's from the crappy DuraTracs that I can't wait to get rid of. I think people just want to hate on any new technology and then there's the "I pAiD fOr A v8 and mUh FrEeDuMz!!!" people...

If you want all the potential failures from the extra technology that gives you 1 mile per gallon at best. Well bless your heart. By the way the 1 mile per gallon is from GM. Every cylinder deactivation vehicle I’ve been in I could feel it and hear it. I’ll never own one. Yup one of those.

Carlos Eduardo Silva Enthusiast

Carlos Eduardo Silva

Posted
Posted

This week I bought a 2022 LTZ (that is the LTD 2021 LOL) and on the Window Stick it doesn't tell anything about the DFM but I also checked my RPO codes and I didn't see the YK9 that someone said that it is the code for engine that has the DFM disabled.

So, I'm not sure 100% sure if my L84 engine has or not the DFM. I hope not.....

 

 

shanemoon Enthusiast

shanemoon

Posted
Posted
6 hours ago, Carlos Eduardo Silva said:

This week I bought a 2022 LTZ (that is the LTD 2021 LOL) and on the Window Stick it doesn't tell anything about the DFM but I also checked my RPO codes and I didn't see the YK9 that someone said that it is the code for engine that has the DFM disabled.

So, I'm not sure 100% sure if my L84 engine has or not the DFM. I hope not.....

 

 

Your truck would have the YK9 code if it was some of the models that came without DFM due to the semi-conductor issues. If that is not on your RPO list, an L84 engine has DFM.

shanemoon Enthusiast

shanemoon

Posted
Posted
11 hours ago, KARNUT said:

If you want all the potential failures from the extra technology that gives you 1 mile per gallon at best. Well bless your heart. By the way the 1 mile per gallon is from GM. Every cylinder deactivation vehicle I’ve been in I could feel it and hear it. I’ll never own one. Yup one of those.

Fair enough...but with that attitude we'd still be using engines from the 70's without any electronics....getting 200HP out of a 8 liter, V8 and getting 7MPG.

Advancement takes trial and error.

AFM and most other "banked" cylinder deactivation were proven to be inferior, so they've developed new dynamic systems that have proven to be very reliable.

KARNUT Senior Enthusiast

KARNUT

Posted
Posted
25 minutes ago, shanemoon said:

Fair enough...but with that attitude we'd still be using engines from the 70's without any electronics....getting 200HP out of a 8 liter, V8 and getting 7MPG.

Advancement takes trial and error.

AFM and most other "banked" cylinder deactivation were proven to be inferior, so they've developed new dynamic systems that have proven to be very reliable.

I don’t have any problems with real advancement. The Frankenstein engines do very little for the costumers. All that extra hardware for 1 mpg. I was interested in the blown 4 cylinder. The had to do cylinder deactivation in that too. My first car was a rotary Mazda. I had a 5.7 GM diesel. 7.3 and 5.9 diesel. The redesign 94 Ram diesel. First in my town with the 94 impala ss and 06 trailblazer ss. New stuff no problem. Frankenstein engines. NO. I buy a V-8 that’s what I want, no tricks. 

shanemoon Enthusiast

shanemoon

Posted
Posted (edited)
19 minutes ago, KARNUT said:

I don’t have any problems with real advancement. The Frankenstein engines do very little for the costumers. All that extra hardware for 1 mpg. I was interested in the blown 4 cylinder. The had to do cylinder deactivation in that too. My first car was a rotary Mazda. I had a 5.7 GM diesel. 7.3 and 5.9 diesel. The redesign 94 Ram diesel. First in my town with the 94 impala ss and 06 trailblazer ss. New stuff no problem. Frankenstein engines. NO. I buy a V-8 that’s what I want, no tricks. 

Every little thing has gotten us to where we are now. 1MPG doesn't seem like alot...but over the course of a year, conservatively that's anywhere from 1300-2000 miles of extra range. Or $400 in gas savings. (also it looks like the L84, 8SPD with DFM delete takes a 2MPG hit to city rather than 1MPG)

And as far as technology goes...it takes small increments to make progress. We don't just jump from getting 7MPG to 25MPG in one generation of engines. It takes time and compounding change.

 

I also don't know that I'd consider cylinder deactivation a "frankenstein engine" lol....the weird Ram E-Torque thing for sure, but cylinder deactivation is mainly software.

 

Almost every car in the coming future will have some sort of cylinder deactivation. Heck they even do it in the Ford GT and most supercar/hypercars now with V8's, V10's and V12's....it just is what it is. It's a pretty proven technology at this point.

 

And it is what has kept GM from going to a hybrid or turbo V6 like Ford and others have. So take your pick....turbo/hybrid V6 or V8 with cylinder deactivation....lol

Edited by shanemoon
KARNUT Senior Enthusiast

KARNUT

Posted
Posted
7 hours ago, shanemoon said:

Every little thing has gotten us to where we are now. 1MPG doesn't seem like alot...but over the course of a year, conservatively that's anywhere from 1300-2000 miles of extra range. Or $400 in gas savings. (also it looks like the L84, 8SPD with DFM delete takes a 2MPG hit to city rather than 1MPG)

And as far as technology goes...it takes small increments to make progress. We don't just jump from getting 7MPG to 25MPG in one generation of engines. It takes time and compounding change.

 

I also don't know that I'd consider cylinder deactivation a "frankenstein engine" lol....the weird Ram E-Torque thing for sure, but cylinder deactivation is mainly software.

 

Almost every car in the coming future will have some sort of cylinder deactivation. Heck they even do it in the Ford GT and most supercar/hypercars now with V8's, V10's and V12's....it just is what it is. It's a pretty proven technology at this point.

 

And it is what has kept GM from going to a hybrid or turbo V6 like Ford and others have. So take your pick....turbo/hybrid V6 or V8 with cylinder deactivation....lol

Turbo hybrid V-6. 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.5k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,924
    Total Members
    8,960
    Most Online
    KirbyCo
    Newest Member
    KirbyCo
    Joined

  • Who's Online   3 Members, 1 Anonymous, 1,442 Guests (See full list)

  • Latest Articles

  • Posts

    • Atlas
      Wow I'm in a pickle. (Broke down truck) and a story.

      By Atlas · Posted

      I will be doing that for sure, but I need to solve who has/ where I can find a bidirectional scan tool that will support OBD 1.5. I'm kicking myself because I ebay'ed a Snap On MT2500 that I didn't think I'd ever need anymore. D'oh!! I'd rather not buy another, so I'll contact a few local shops to see if they have one and how much they'd want to do the procedure. I'd rather have the ability to do it myself... I wish there was a modern tool that could do it all, but I'd have no idea what to buy.   The theory with the pulled timing is that it mimics a rich condition. The delayed spark causes incomplete burn and the O2 sensor picks up low oxygen levels. That's interpreted as a rich condition so the PCM pulls fuel and that shows up in the deeply negative fuel trims.
    • Chuck FB
      Joke Thread

      By Chuck FB · Posted

      An ultra wealthy man had the most beautiful daughter. But, there was a problem. Everything she touched would melt in her hands. No matter what, Metal, Wood, Stone. Anything she touched would melt. She could not feed herself. Because of this, men were afraid of her. Nobody would dare marry her. Her father was despaired. What could he do to help his daughter? He consulted doctors, scientists and anybody who could solve this problem. Finally one of them said, "If your daughter touches one thing that does not melt in her hands, she will be cured." He was overjoyed and came up with a plan. The next day, he held a competition. Any man who could bring his daughter an object that would not melt in her hands would be given billions of dollars to marry her. Three extremely intelligent and handsome young men took up the challenge. The first brought a very heavy steel rod, But alas, when the she touched it, it completely melted in a matter of seconds. He sadly went away. The second brought a beautiful diamond, knowing diamonds were one of the hardest substance in the world and would not melt. But alas, once she held it in her hand, it melted. He too was sent away disappointed. So now, there was one left He was very nervous & sweating. He approached the daughter & said, “put your hand in my pants pocket and feel what is in there." She did exactly what he asked. She felt something very hard. She held it in her hand, squeezing it as hard as she could. It did not melt & remained extremely hard. Her father was overjoyed. Everybody was overjoyed. She was finally cured. Nothing never, ever melted in her hand again. They married and they both lived happily ever after, raising a wonderful family. Question: What was in the the groom’s pants pocket??? Answer below ↓ M&Ms of course! They melt in your mouth, not in your hand. What on earth were you thinking?
    • asilverblazer
      Wow I'm in a pickle. (Broke down truck) and a story.

      By asilverblazer · Posted

      There's a bunch of tea leaves that you've read, but in any case the delayed timing is unusual. Not sure how that relates to the rich at idle vs. 'normal' while driving.   If you're in this deep, might be worth investigating, and re-learning the sensor. What have you got to lose? Plus, it properly fixes the timing cover leak.
    • asilverblazer
      Wow I'm in a pickle. (Broke down truck) and a story.

      By asilverblazer · Posted

      The only problem I have seen this cause is longer crank times. 
    • Atlas
      Wow I'm in a pickle. (Broke down truck) and a story.

      By Atlas · Posted

      Injector is being sent off today for rebuild and I estimate I'll have it back in 10 days or so.   It may not be the injector...of course...now that I've torn down the intake again. But, let's rule out the injector and replace those spider legs that have been almost rubbed through.   The truck has always had negative timing and I'm reading "normal" timing at warm idle should be +16 or so. I'm negative 16 to 25 or more, and it's always been like that since I bought it.   A light turned on upstairs last night in the old noggin. Rare, I know...   This will be wild, if it turns out to be the cause!   In 2001, according to the old service documentation, the muffler was replaced. Why? I have no idea, it wouldn't have been rusted through by then. But they did a crappy job.   In 2019, another shop replaced it and noted the prior install was poorly done on the work order. "Exhaust system vibrates on crossmember". Except...I guess they just left it be? I believe the husband, the couple who were original owners, had passed by then. Maybe she said it's just not worth it to have the exhaust system fixed and declined repairs. Very few miles were driven between 2019 and 2025.   The exhaust system vibrates heavily on the crossmember and you can feel it and REALLY hear it, even today. Not always, but at idle, it gets going pretty good sometimes.   What if....   ....What if that's enough to trigger one or both of the knock sensors? Could it be tricking the sensors into sensing knock, so it's pulling timing aggressively? Pulling timing heavily means it's firing after the piston reaches full height which means incomplete burn which means the O2 sensor is sensing a rich condition, which means I've been chasing my tail, and what I thought was an inconsequential problem (janky exhaust) has been THE issue for this truck for 25 solid years?   That would be wild. Maybe it IS wild.   The service documentation thereafter, for years, shows visits for rough idle, replacing O2's, replacing the cat, replacing plugs and wires, a misfire condition, like they could never solve the issue. The injector has been replaced 4 times in 80k miles, that's just crazy.   The secondary theory....   The engine has clearly had a leak at the front seal for a very long time (the greasy trench...). I think the truck changed hands quickly ~2025 because there's Napa receipts from someone I don't recognize in the ownership history. They apparently replaced the timing cover seal, and they did a terrible job. There's RTV smeared all over and the leak I had reduced to a weep by snugging the front oil pan bolts is now a leak again.   HOWEVER....I read about replacing the crankshaft position sensor. Any time the ckp sensor is disturbed or timing cover is removed, the truck requires relearning, and that can only be done through a bi-directional scan tool. Skippy with the RTV probably didn't do the relearn procedure is my guess. His scan tool is lost in a pile of RTV goo somewhere.   So, it's very possible the sensor has been disturbed and the truck is just running on the old learn data but not setting a code for anything. The distributor has since been replaced and so has the camshaft position sensor, so all bets are off for that thing.   In the theme of one step forward, two steps back, I returned the accumulator for the AC. The gal I've been working with at O'Really's has been great. She refunded it under manufacturer's defect and we compared it to the replacement I ordered, and sure enough, the replacement is machined very differently (and a gauge actually fits on it!).   Got it home, installed it, started vacuuming it down.... and I couldn't get good vacuum.   The high side service port, where I replaced the old GM ball valve suspecting that was a source of the previous leak....well, I've clearly exposed whatever pre-existing crack in the line where the service port is welded, and made it much worse. Blessing in disguise? Except there goes another $25, now I'm waiting for a replacement AC line.   In 10-ish days ALL the parts will be here. Rebuilt injector, new exhaust system, new cat, new high pressure AC line.   Oh, did I mention the squeaking ISN'T coming from the AC pump? The truck still squeaks when started, and there were words after I started it with the new AC pump installed. But, there was more to replacing the AC pump for just a squeak. A truck with good working AC is something of value, for the comfort alone.   I've ordered a new harmonic balancer because, 30 years is a good run for one of those. Rule it out. The squeak may be something more sinister, though. I'm worried about that ckp sensor and if it was shimmed correctly, or if the timing set was installed correctly. The squeak may be coming from UNDER the timing cover.   At this point, once I get it put back together, I'm thinking I'll take a 50 mile victory lap and then promptly put it up for sale. This truck is cursed. Betty, from beyond the grave, doesn't want anyone messing with her Blazer. Or maybe she's getting revenge for 30 years of shop visits with that thing.

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...