Jump to content

DFM yes or no

RSTJohn

By RSTJohn
in Modifications, Wheels & Tires

 Share

Recommended Posts

RSTJohn Enthusiast

RSTJohn

Posted
Posted

Is there a way to do a survey of 5.3 owners that just let DFM work as designed compared to those that delete DFM one way or another?

KARNUT Senior Enthusiast

KARNUT

Posted
Posted (edited)
1 hour ago, RSTJohn said:

Is there a way to do a survey of 5.3 owners that just let DFM work as designed compared to those that delete DFM one way or another?

It’s been done on older cylinder deactivation models. In my case on an older vehicle at 70 mph. There wasn’t enough difference to register. Of course there’s outliers. Some doing low speed testing claim some difference. If you look one some new truck stickers or information the claim is 1 mile per gallon. 

Edited by KARNUT
Bikerjon Enthusiast

Bikerjon

Posted
Posted

My 2021 Trail Boss Custom did not have DFM or Auto Start but if it did I would definitely disable it. There has been a lot of problems associated with DFM.

Z45 Senior Enthusiast

Z45

Posted
Posted

According to GM:

    Internal components related to AFM or DFM function will be present in engines; wiring, connectors, and fuses will be present in vehicles with RPO YK9. The ECM will not be capable of activating the cylinder deactivation technology.

    When diagnosing and repairing concerns with base engine or electrical function which may be related to AFM or DFM related hardware; utilize appropriate diagnostics within SI and replace any needed components as directed by the Electronic Parts Catalog; no changes will occur to AFM or DFM related components.

    Important: Any truck designated with RPO YK9 CANNOT be reprogrammed and changed to “Turn on” the AFM/DFM functionality.

RetCPO Enthusiast

RetCPO

Posted
Posted

2020 AT4 5.3 w/dfm. I always drive in L9 dfm won't engage, but I do lose 10th gear.

I'd rather have 8cyl all the time. Not sure what the mpg loss is on the highway but I'm not worried about it.

CamGTP Senior Enthusiast

CamGTP

Posted
Posted

My parents have a 2021 5.3 with DFM, I've driven it many times and towed with it several times and I can barely notice the DFM working. The AFM trucks are alot more noticeable if you ask me. It's only got like 5,000 miles on the truck and it's been problem free.

  • Like 1
2020RSTBorla Enthusiast

2020RSTBorla

Posted
Posted

I recently added the Pulsar LT.

 

I was getting a mild shudder in certain situations and it was concerning.  Since turning off DFM it has completely disappeared and imo the shifting is much improved.

 

I have the throttle sensitivity set to 3 and I love it!  It took a few days to get used to the new throttle response.  Like when you drive a car that has a sensitive brake pedal and you are used to a more mushy brake pedal.  

 

Turning off Auto start/stop is also a great thing.  Still getting used to not having to turn it off.

 

This thread is about DFM, but I love the Pulsar LT and I love not having DFM on anymore.  It is very noticeable, at least to me.  I have a Borla Touring cat back exhaust with S&B cai.

BossTaco2020 Enthusiast

BossTaco2020

Posted
Posted

2020 TrailBoss LT w/5.3 & DFM. I never notice it and haven't tried to disable it. 37K miles and running like I bought her yesterday.

Street Queen Enthusiast

Street Queen

Posted
Posted

Going from a 2019 Silverado with DFM to a 2022 Refresh TB W/O DFM, I definitely like not having DFM.  If you can snag one w/o DFM I recommend pulling the trigger ASAP B4 DFM is standard again.

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

    342,980
    Total Members
    8,960
    Most Online
    Fishboat
    Newest Member
    Fishboat
    Joined

  • Who's Online   2 Members, 0 Anonymous, 516 Guests (See full list)

  • Latest Articles

  • Posts

    • Grumpy Bear
      AFM Experience

      By Grumpy Bear · Posted

      Question @diyer2 on this line if you please. Are you saying the shudder is the system turning on and off at the frequency of the shudder? Guess I'm asking if you are saying you have seen it do this with the bi-direction scan tool in graph mode? If so have you been able to discern the 'trigger'. Something is telling to cycle rapidly.    My truck just started doing this recently. 197K on the clock. My response has been M5 anything under 55 mph. I treat it like a lugging stick shift. Gear down and let it spin a bit. Engauge M5, then tow mode and then M6 lets the trans stay in 5th but the AFM is active. Smooth like Skippy.    My thought was that as a machine ages the friction gets lower and as the system is load based, the lower friction would allow it to turn on at ever lower rpm until it reaches the lugging point. And yes I am ignorant of any minimum rpm requirement for the system. If you know that would be useful information.    As you know I run a Scan-Gauge II which allows me to watch the On/Off of the signal to the VLOM. While in the shudder mode I'm not seeing is cycle at that frequency or at all for that matter outside the triggers @newdude posted a few years back. Now is it possible that the refresh rate isn't fast enough to catch it? Maybe. It is why I asked my first question about graphing and trigging parameter.     As we have observed from members here the failure point is all over the map miles wise as you note yourself in your opening post. That by itself begs a few questions like fellows that comment on these lifters failing even after the system has been disabled. Long after. 😬   https://www.enginelabs.com/news/tech-tips-replacing-ls-active-fuel-management-lifters-with-melling/   The Gen5 lifters operate the same as the LS versions. In fact they are the same lifter.    https://www.enginelabs.com/tech-stories/sorting-out-gen-v-lt-lifter-failure-with-a-simple-valvetrain-fix/        
    • SwitchBladeSierra
      14-18 Sierra 1500 Heated Steering Wheel Help

      By SwitchBladeSierra · Posted

      UPDATE 2: Steering wheel control backlights and control of the cluster can supposedly be achieved by adding a wire to pin 20 of the cluster and tapping it to pin 2 of the main clock spring harness. I'm going to give it a shot - will update  
    • newdude
      Seems to be Missing a lot of Updates

      By newdude · Posted

      GM Global A pickups 2019-2022 can do OTA programming for the radio.  GM VIP (GM Global B) can do OTAs for almost every module on board.  So a 2022.5 and newer pickup can do OTAs for recalls like the 2.7 fuel flow recall.  EVs get OTAs that improve one pedal driving, radio issues, HVAC issues, updated battery management software, etc.     So age of the vehicle/what GM electrical platform its on will alter what amount of updates can be pushed on OTAs.  
    • Blade8971
      Upgrade to a 2026 AT4 with the 3.0L Duramax

      By Blade8971 · Posted

      Thank You.   So far my new ride is making me look like a genius for going with the 3.0L, as my first fuel refill occurred over three weeks from when I took delivery.  This engine combination is very amazing.  So far no issues and had not done a regen yet.
    • Chuck FB
      Correct way to service 2024 l8t allison trans?

      By Chuck FB · Posted

      I am curious as to how much fluid you put back in the transmission ( assuming you had replaced the filter to compare to my findings ) and then went through the process of warming up the trans before pulling the check plug to drain out the excess and if you measured how much came back out.    I just found it surprising that some claimed a certain amount less fluid being put in and then draining some back out. The attitude of the truck as per if the surface is level and how the trucks stance is would make quite a difference since the check plug is right at the front of the transmission. 

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...