DFM shudder/vibration getting worse

[matt grz]

Does anyone else notice their DFM shudder getting worse with time?  

I took my 2020 gmc Sierra with 5.3 and 10 speed to a dealer with concerns about the low rpm shuddering and they told me it’s DFM and they can’t do anything to stop it.  
 

This was the same dealer that resolved my driveline vibration with shims, but this time around I got the feeling they didn’t want to deal with me.
 

To test their theory I installed a pulsar to ensure it is the DFM.  It for sure has to do with DFM because the shudder is gone when DFM is disabled.

 

I took it to a different local dealer with the pulsar installed and he told me that the pulsar will void warranty and wouldn’t even look at my truck.  This scared me so I took the pulsar off right away.  The jag off made sure he noted it in his write up too.  I maybe had the pulsar on for 3 days or so and it ran beautifully with that module installed.

 

I notice the older this truck gets (2020 with 18,000 miles) the worse the vibration gets.  I notice it at all of the speeds I typically drive (25mph, 45 mph, 60 mph) it happens when I just toe into the accelerator to maintain speed.  I feel like something is causing this and it’s not just typical DFM.  It didn’t do it when the truck was new and it’s progressively getting worse.  
 

It almost feels like transmission or TCC related to me, but I’m not a mechanic and I’m not sure if it makes sense that this would be the issue if it doesn’t do the shudder when DFM is disabled.

 

I reached out to the GM customer service people that sometimes replies in this forum, maybe they’ll help me out.

 

Has anyone found a fix for this?  Does anyone know of a solid dealer that will take the time to really look into this issue in the Chicagoland area?  I feel like the dealers around here are easily bothered and just want to get rid of you.  Thank you all in advance.

[Transient]

I have 39,000 on my 2020 Silverado. 6.2 with 10 speed. No issues that I've noticed. 

 

 

 

I use to live in Highland Park (2012-2015). I had Chevys back then, too. Never found a good dealer out there.  Maybe check with GMC or Cadillac dealers since they're more "upscale" and kissing butt is more important to those who spend more money on the exact same product you have. 

 

Dealer that told you the Pulsar voids your warranty is full of crap.  It doesn't.  They'd have to prove it caused a failure to deny warranty coverage.  This is covered in federal law called the Magnuson-Moss Warranty Act.  I recommend reading it and getting familiar with the law so you can call BS on dealers that try that crap.  I've had to drop a copy of that on the service writer's desk a couple of times to remind them of how stupid they are for saying things like that.  I suspect if I didn't move every couple of years I wouldn't have to flex so much with those guys, but it is what it is.  Getting ready to move from California to Florida in a couple of months. 

 

 

 

 

[Z45]

I have a 2021 6.2L/10sp and can't tell when DFM is working.

?Is your truck 100% stock, no oversize tires?

 

 

[matt grz]

3 hours ago, elcamino said:

I have a 2021 6.2L/10sp and can't tell when DFM is working.

?Is your truck 100% stock, no oversize tires?

 

 

I had gmc install the 2” lift and I also had gmc install the Borla exhaust.  Tires are stock.

[Z45]

I wonder if the exhaust is amplifying it??    Making you more aware??  Don't know but seems plausible as I have heard others with AFM engine say it was worse with modified exhaust. 

Edited December 30, 2022 by elcamino

[newdude]

12 hours ago, Matt Grz said:

Does anyone else notice their DFM shudder getting worse with time?  

I took my 2020 gmc Sierra with 5.3 and 10 speed to a dealer with concerns about the low rpm shuddering and they told me it’s DFM and they can’t do anything to stop it.  
 

This was the same dealer that resolved my driveline vibration with shims, but this time around I got the feeling they didn’t want to deal with me.
 

To test their theory I installed a pulsar to ensure it is the DFM.  It for sure has to do with DFM because the shudder is gone when DFM is disabled.

 

I took it to a different local dealer with the pulsar installed and he told me that the pulsar will void warranty and wouldn’t even look at my truck.  This scared me so I took the pulsar off right away.  The jag off made sure he noted it in his write up too.  I maybe had the pulsar on for 3 days or so and it ran beautifully with that module installed.

 

I notice the older this truck gets (2020 with 18,000 miles) the worse the vibration gets.  I notice it at all of the speeds I typically drive (25mph, 45 mph, 60 mph) it happens when I just toe into the accelerator to maintain speed.  I feel like something is causing this and it’s not just typical DFM.  It didn’t do it when the truck was new and it’s progressively getting worse.  
 

It almost feels like transmission or TCC related to me, but I’m not a mechanic and I’m not sure if it makes sense that this would be the issue if it doesn’t do the shudder when DFM is disabled.

 

I reached out to the GM customer service people that sometimes replies in this forum, maybe they’ll help me out.

 

Has anyone found a fix for this?  Does anyone know of a solid dealer that will take the time to really look into this issue in the Chicagoland area?  I feel like the dealers around here are easily bothered and just want to get rid of you.  Thank you all in advance.

 

 

Take the Pulsar off and have the dealer test the torque converter operation.  Specifically looking at the converter slip speed.  During normal operation it should be no more than a 20rpm slip.  If its higher than that, its either a fluid related cause or the torque converter is on its way out.  If its all good, I'd suspect some exhaust amplification of the vibration.  

Also.  Read below.  Hopefully they didn't submit that labor op on your VIN because then you might be SOL.  

 

8 hours ago, Transient said:

I have 39,000 on my 2020 Silverado. 6.2 with 10 speed. No issues that I've noticed. 

 

 

 

I use to live in Highland Park (2012-2015). I had Chevys back then, too. Never found a good dealer out there.  Maybe check with GMC or Cadillac dealers since they're more "upscale" and kissing butt is more important to those who spend more money on the exact same product you have. 

 

Dealer that told you the Pulsar voids your warranty is full of crap.  It doesn't.  They'd have to prove it caused a failure to deny warranty coverage.  This is covered in federal law called the Magnuson-Moss Warranty Act.  I recommend reading it and getting familiar with the law so you can call BS on dealers that try that crap.  I've had to drop a copy of that on the service writer's desk a couple of times to remind them of how stupid they are for saying things like that.  I suspect if I didn't move every couple of years I wouldn't have to flex so much with those guys, but it is what it is.  Getting ready to move from California to Florida in a couple of months. 

 

 

 

Mag-Moss, shmag moss.  Here's what GM says:

 

09-00-89-016G: Warranty Administration – Labor Operation 0600014 – Suspected Tampering or Vehicle Modifications 

 

Tampering is defined as causing intentional modification to a vehicle or vehicle components and is not covered under the terms of the GM New Vehicle Limited Warranty.

Tampering can include, but is not limited to:

• inducing an electrical component and/or system failures
• disconnecting wires or connectors
• intentional contamination of fluids

Non-GM vehicle modifications include, but are not limited to:

• installation of non-GM accessories
• installation of suspension lowering or lift kits
• installation of aftermarket tires and/or wheels
• installation of “power-up chip” and/or non-GM control module calibrations.

 

 

Edited December 30, 2022 by newdude

[matt grz]

4 hours ago, newdude said:

 

 

Take the Pulsar off and have the dealer test the torque converter operation.  Specifically looking at the converter slip speed.  During normal operation it should be no more than a 20rpm slip.  If its higher than that, its either a fluid related cause or the torque converter is on its way out.  

Also.  Read below.  Hopefully they didn't submit that labor op on your VIN because then you might be SOL.  

 

 

 

09-00-89-016G: Warranty Administration – Labor Operation 0600014 – Suspected Tampering or Vehicle Modifications 

 

Tampering is defined as causing intentional modification to a vehicle or vehicle components and is not covered under the terms of the GM New Vehicle Limited Warranty.

Tampering can include, but is not limited to:

• inducing an electrical component and/or system failures
• disconnecting wires or connectors
• intentional contamination of fluids

Non-GM vehicle modifications include, but are not limited to:

• installation of non-GM accessories
• installation of suspension lowering or lift kits
• installation of aftermarket tires and/or wheels
• installation of “power-up chip” and/or non-GM control module calibrations.

 

 

It doesn’t show a labor number, just a note that says inspection found an aftermarket pulsar lt programmer installed to vehicle.  I sure hope they didn’t do that the jerks.  Thank you for the torque converter info.  Hopefully the next dealership is decent.

 

Edited December 30, 2022 by Matt Grz

[GMCustomerService]

9 hours ago, Matt Grz said:

Does anyone else notice their DFM shudder getting worse with time?  

I took my 2020 gmc Sierra with 5.3 and 10 speed to a dealer with concerns about the low rpm shuddering and they told me it’s DFM and they can’t do anything to stop it.  
 

This was the same dealer that resolved my driveline vibration with shims, but this time around I got the feeling they didn’t want to deal with me.
 

To test their theory I installed a pulsar to ensure it is the DFM.  It for sure has to do with DFM because the shudder is gone when DFM is disabled.

 

I took it to a different local dealer with the pulsar installed and he told me that the pulsar will void warranty and wouldn’t even look at my truck.  This scared me so I took the pulsar off right away.  The jag off made sure he noted it in his write up too.  I maybe had the pulsar on for 3 days or so and it ran beautifully with that module installed.

 

I notice the older this truck gets (2020 with 18,000 miles) the worse the vibration gets.  I notice it at all of the speeds I typically drive (25mph, 45 mph, 60 mph) it happens when I just toe into the accelerator to maintain speed.  I feel like something is causing this and it’s not just typical DFM.  It didn’t do it when the truck was new and it’s progressively getting worse.  
 

It almost feels like transmission or TCC related to me, but I’m not a mechanic and I’m not sure if it makes sense that this would be the issue if it doesn’t do the shudder when DFM is disabled.

 

I reached out to the GM customer service people that sometimes replies in this forum, maybe they’ll help me out.

 

Has anyone found a fix for this?  Does anyone know of a solid dealer that will take the time to really look into this issue in the Chicagoland area?  I feel like the dealers around here are easily bothered and just want to get rid of you.  Thank you all in advance.

This is certainly not what we like to hear, Matt Grz.  Please know, customer satisfaction is extremely important to us. Our team would be more than happy to take a closer look into the concerns with your 2020 GMC Sierra. To do so, please send an email to [email protected] with ATTN: Matt Grz/GM Trucks in the subject line.

Please include your contact information, VIN, a brief description of your concern, and the name of your preferred dealership. We look forward to hearing from you. To learn more about GM’s Privacy Policy, please visit https://www.gm.com/privacy-statement.html. The information you provide may be monitored and recorded and is subject to the GM Privacy Statement.
 
Privacy Statement | General Motors
Your privacy is important to General Motors. This Privacy Statement addresses the personal information GM collects and how GM handles that personal information.
www.gm.com

[matt grz]

28 minutes ago, GMCustomerService said:

This is certainly not what we like to hear, Matt Grz.  Please know, customer satisfaction is extremely important to us. Our team would be more than happy to take a closer look into the concerns with your 2020 GMC Sierra. To do so, please send an email to [email protected] with ATTN: Matt Grz/GM Trucks in the subject line.

Please include your contact information, VIN, a brief description of your concern, and the name of your preferred dealership. We look forward to hearing from you. To learn more about GM’s Privacy Policy, please visit https://www.gm.com/privacy-statement.html. The information you provide may be monitored and recorded and is subject to the GM Privacy Statement.
 
Privacy Statement | General Motors
Your privacy is important to General Motors. This Privacy Statement addresses the personal information GM collects and how GM handles that personal information.
www.gm.com

I contacted You guys using a different subject line.  I really hope you guys can help me get this resolved.  Thank you.

[Silverado4x4]

34 minutes ago, Matt Grz said:

I contacted You guys using a different subject line.  I really hope you guys can help me get this resolved.  Thank you.

Taking it to a different dealer is not going to help as what your dealership entered in the comments the system will show at every dealership.

[matt grz]

21 minutes ago, Silverado4x4 said:

Taking it to a different dealer is not going to help as what your dealership entered in the comments the system will show at every dealership.

Yeah but the pulsar has nothing to do with this issue.  The issue was there before the pulsar was installed.  The pulsar just confirmed that the issue is only there when DFM is active.  I’d be real pissed if they pulled some BS about the pulsar.

[Z45]

Unfortunately its makes no difference to them.  Rarely does a dealer or GM back down unfortunately.  Big mistake leaving that on the truck IMO. 

[Amcguy1970]

7 hours ago, Transient said:

I have 39,000 on my 2020 Silverado. 6.2 with 10 speed. No issues that I've noticed. 

 

 

 

I use to live in Highland Park (2012-2015). I had Chevys back then, too. Never found a good dealer out there.  Maybe check with GMC or Cadillac dealers since they're more "upscale" and kissing butt is more important to those who spend more money on the exact same product you have. 

 

Dealer that told you the Pulsar voids your warranty is full of crap.  It doesn't.  They'd have to prove it caused a failure to deny warranty coverage.  This is covered in federal law called the Magnuson-Moss Warranty Act.  I recommend reading it and getting familiar with the law so you can call BS on dealers that try that crap.  I've had to drop a copy of that on the service writer's desk a couple of times to remind them of how stupid they are for saying things like that.  I suspect if I didn't move every couple of years I wouldn't have to flex so much with those guys, but it is what it is.  Getting ready to move from California to Florida in a couple of months. 

 

 

 

 

Um, the Pulsar is a low scale tuner type device, alternating how the vehicle was designed to operate sure can cause warranty issues; so no it isn't BS. People love dropping the "Magnuson Act" like it give complete protection, well it also works the other way for the manufacturers. The Pulsar even states to remove it prior to retain factory warranty. If they know it was on there they can deny your warranty depending on what you are trying to claim. Shoot, going in for a shudder caused by DFM and having a device on there specifically to change DFM, I would deny that too if I knew about it. 

 

Tyler

[matt grz]

12 minutes ago, Amcguy1970 said:

Um, the Pulsar is a low scale tuner type device, alternating how the vehicle was designed to operate sure can cause warranty issues; so no it isn't BS. People love dropping the "Magnuson Act" like it give complete protection, well it also works the other way for the manufacturers. The Pulsar even states to remove it prior to retain factory warranty. If they know it was on there they can deny your warranty depending on what you are trying to claim. Shoot, going in for a shudder caused by DFM and having a device on there specifically to change DFM, I would deny that too if I knew about it. 

 

Tyler

Well when I returned the pulsar to range technology based on what the dealer told me range felt the dealer was misinformed.  I guess we will see how it all plays out.

[Weaverstreet]

My 2019 LT 5.3 with an 8 speed is experiencing the shudder again and the service writer at Covina Hills Chevrolet told me that this time  it's because I had it in 4 wheel auto (It's raining) . The advisor told me that the front and rear axle ratios are not the same and this is the cause when you run it in 4 wheel auto. That sounds very odd to me?  GM's brochure states tht you can leave it in 4 wheel auto continuously. I had a video of it  surging up a hill and they were not interested in watching it whatsoever. Feels like I'm getting scammed or they are trying to  wait until it passes 36K and they can charge me for the repair. This is it's second time it's in for the issue. The first time they held it for a few days saying they couldn't get it to act up before they finally said it was fine after they inspected the pan magnets for metal. It ran fine for a couple of days afterwards and then slowly returned to it's herky-jerky self. Now they want me to miss more work to come and ride around with the technician so he can try to feed me more bs I guess. Now Why would I ever consider another GM product? I miss my 07 now.