DFM disable?

Transient · October 20, 2021

On 5/1/2020 at 9:43 AM, Thomcat said:

Early AFM systems developed oil burning problems caused by the discharge oil spray in the sump on nearby cylinders clogging the oil rings.In addition there were problems with the collapsible lifters of time oil problems at 60K+ and lifters at around 100K miles. Solenoids were never the problem, in fact the LOMA manifold with its own screen clogging problems, exclusive to AFM engines also uses them for the 4 AFM cylinders. Post 1/11 AFM production has addressed these problems with modified valve cover, modified PCV system, baffle over the AFM oil discharge valve, and a new gen of collapsible lifters less prone to damage caused dirty oil. Later volume increase of 5.3l sump capacity from 6 to 8 qts has also helped to extend oil life.

Here's my .02 opinion, take it for what it is worth. Had AFMs on my 3 Avalanches and '16 Silverado and by comparison the DFM system is totally seamless. I used the Range device in my '07 Avalanche because it had the early system with valve cover, lifter, PCV and AFM discharge problems. Never used it on the later ones nor will I use one on the '19 DFM because as far as I'm concerned there is no long term data on the new DFM system, talking years not accelerated studies, on use of a defeat device vs. use without one. Got to figure it has to be pulled periodically whenever car is taken for service, State inspections, grabbing codes for the EL, etc. Dealer spots it and no more electrical warranty.

The AFM and DFM engines are designed for operation on a varying number of cylinders and the solenoids along with the collapsible lifters are designed to flex thousand of times during each drive cycle. So I'd like to know what the effects would be of keeping the oil control solenoids idle or maybe worse open under constant voltage for an extended period....heat buildup?, varnish deposits inside tappets?....and what happens to collapsible lifters that remain in the one position for very long periods when the device is removed for inspection or service and they expand/collapse and jamb with accumulated varnish buildup in a static area? And what of variability of vehicle builds and that any particular gizmo will play friendly with each and every module programming in your particular vehicle as equipped ?.

I don't know and I don't think GM knows either since a DFM engine is barely 2 years old plus was not designed for usage in that manner......but I don't have to because system works just fine as is, plenty of pep and seamless operation.......and it makes no sense to fix something that isn't broken.

This is the nice way to put it. Glad you wrote this post. I'm not as forgiving. I'm more blunt. Why would anybody buy the truck if it has a design from the factory you think will fail? Are Nissan, Toyota, Ford, and Ram even worse? I doubt it, therefore people are just complaining for the sake of complaining.

KARNUT · October 20, 2021

7 hours ago, Transient said:

This is the nice way to put it. Glad you wrote this post. I'm not as forgiving. I'm more blunt. Why would anybody buy the truck if it has a design from the factory you think will fail? Are Nissan, Toyota, Ford, and Ram even worse? I doubt it, therefore people are just complaining for the sake of complaining.

They wouldn’t, once burned. My whole family was GM in the 60s and 70s. The 5.7 diesel drove some away. The 6.5 in trucks drove the rest. We drove 7.3 and 5.9s after. The we went back to gas after the emissions on diesel. My parents still have theirs. I started driving GM trucks again in 2001. The cylinder deactivation drove me away. I honestly don’t know what I would buy if I needed a new one. There’s only one real V-8 left. Never drove a Nissan. I’m not afraid of new things. My first car was an RX3.

Grumpy Bear · October 20, 2021

On 4/29/2020 at 12:39 PM, Orlick82 said:

Is it true you have to change the internals of the motor if you’re going to delete DFM?

No. Chip shortage anyone?

On 4/30/2020 at 7:15 PM, 175vTrailbossLT said:

There’s a plate with solenoids that are pressurized off of oil pressure. If the solenoids fail or there’s an issue with oil pressure, well there you go- a good way to burn off a cylinder or head..block..whatever.

is this controlled by software or is a physical mod required that voids warranty?

Software solution. Chip shortage anyone?

On 5/1/2020 at 11:43 AM, Thomcat said:

So I'd like to know what the effects would be of keeping the oil control solenoids idle or maybe worse open under constant voltage for an extended period....heat buildup?, varnish deposits inside tappets?....and what happens to collapsible lifters that remain in the one position for very long periods when the device is removed for inspection or service and they expand/collapse and jamb with accumulated varnish buildup in a static area?

Varnish is not a cycling of components issue. It's an oil MAINTENANCE issue. Maintain the oil in accordance with the oils abilities and there will never be any varnish and darn little wear. As far a a lifter not cycling for long periods of time...Humm....ever break a coat hanger by bending it back and forth past it's elastic limit? What happens if you don't bend it?

When the system is idle the solenoids are not under power. They will not overheat. They are inactive.

Chip shortage anyone?

Material science is not Voodoo. Accelerated studies are valid. Doesn't matter if the paint wears through by mother washing the walls over 20 years or a machine does the rubs of 20 years worth of cleaning in 10 minutes. One rub is one rub. Ditto cycle testing solenoids, valves, connecting rods. It's how GM developed the SBC rods in the early 50's for infinite life cycles. (Peterson Publications, Hot to Hotrod the SBC) Even today on those that are operated inside the test loads NEVER fail. Only the abused do.... D'ho...you mean it wasn't designed to be spun 10,000 rpm with 20 pounds of boost? :idiot:

shakenfake · October 20, 2021

You do have to change the internals of the engine to delete it. It's only the camshaft and lifters though. That was on the AFM though. AFM would fail because of hardware issues. A lot of people would have AFM failure even though it was deleted since day one or shortly thereafter.

This new DFM system I am not sure I have heard of anyone with a failure that doesn't have the chip in it. Could it be that they figured out how to keep the hardware from failing and now just have software failures? Hmmmm

milkmaster · October 20, 2021

This discussion makes me feel good about buying a 2021 Sierra SLT chip shortage truck. No DFM or at least it is deactivated. Some have mentioned the parts are still there, but that's ok. I still am happy with it so far. The truck was built in June at the Mexico plant according to the sticker. It's got a little over 2k miles on it since July with no complaints about anything. I hope it stays that way.

Transient · October 21, 2021

15 hours ago, milkmaster said:

This discussion makes me feel good about buying a 2021 Sierra SLT chip shortage truck. No DFM or at least it is deactivated. Some have mentioned the parts are still there, but that's ok. I still am happy with it so far. The truck was built in June at the Mexico plant according to the sticker. It's got a little over 2k miles on it since July with no complaints about anything. I hope it stays that way.

Your truck may have been built in Mexico, but the engine was likely built in New York.

Transient · October 21, 2021

20 hours ago, KARNUT said:

They wouldn’t, once burned. My whole family was GM in the 60s and 70s. The 5.7 diesel drove some away. The 6.5 in trucks drove the rest. We drove 7.3 and 5.9s after. The we went back to gas after the emissions on diesel. My parents still have theirs. I started driving GM trucks again in 2001. The cylinder deactivation drove me away. I honestly don’t know what I would buy if I needed a new one. There’s only one real V-8 left. Never drove a Nissan. I’m not afraid of new things. My first car was an RX3.

People always find failures they justify as a means for them to give up. Nobody ever finds praise to remain loyal. Seems like society focuses on the glass being half empty the majority of the time.

As for Nissan's, I've found the slightest touch of the gas peddle moves the vehicle suddenly and quickly. I think it's a little too aggressive. That's just my opinion, though.

Btw, given the topic of the thread, I read an article Google suggested that was about oil consumption. Abridged version: Don't own a vehicle from MY2010-2012. Seems like everybody has the issue. Acura, Audi, Honda, Volkswagen, etc all suffered from oil consumption. If they can find a way to fix the problem, so can GM. In another article I read, GM is focused on reducing Green House Gas emissions. Their goal next year is greater than 10% reduction. They already achieved over 5%. Killing off the 4.3 V6 and the 5.3 AFM is believed will help achieve this goal. They indicated such in the Q3 2021 investors call.

Edited October 21, 2021 by Transient

KARNUT · October 21, 2021

1 hour ago, Transient said:

People always find failures they justify as a means for them to give up. Nobody ever finds praise to remain loyal. Seems like society focuses on the glass being half empty the majority of the time.

As for Nissan's, I've found the slightest touch of the gas peddle moves the vehicle suddenly and quickly. I think it's a little too aggressive. That's just my opinion, though.

Btw, given the topic of the thread, I read an article Google suggested that was about oil consumption. Abridged version: Don't own a vehicle from MY2010-2012. Seems like everybody has the issue. Acura, Audi, Honda, Volkswagen, etc all suffered from oil consumption. If they can find a way to fix the problem, so can GM. In another article I read, GM is focused on reducing Green House Gas emissions. Their goal next year is greater than 10% reduction. They already achieved over 5%. Killing off the 4.3 V6 and the 5.3 AFM is believed will help achieve this goal. They indicated such in the Q3 2021 investors call.

The first failure was the 5.7 diesel as stated. If it was one no problem things happen. It was 4 out of 4. GM at the time was gee we haven’t heard of that. The 6.5 was a little better. The first one lost an injection pump under warranty. The dealer this time said we’re seeing failures around 80K miles. We had 3. I had 91 Ram diesel at the time. It was a beast. We stayed with those with the exception of my moms 2000 7.3. She still drives it. My father 98 Rams still around. I’m the only one that went to GM. I had a 01, 04. 06, then I strayed for awhile. Bought my 14 for retirement. Saw the cylinder deactivation. Joined this forum read up on cylinder deactivation. And passed. My 14 was the quietest, quickest, hands down best truck I ever owned. Love it, except for that Frankenstein engine. Not about an half full cup. I was about to put serious mods on the engine and replace my blown 92 Chevy. I sold the 14 keep the 92 another 5 trouble free years. Fool me once…….

fastk9dad · October 21, 2021

Just as a counterpoint to some of the concerns in this discussion...

I had a '09 Tahoe 5.3 w/AFM. Traded in at 219k. Mobil1 & AC Delco filters through out its life & only switched to high mileage M1 once over 200k. Oil changes were generally done when OLI was around 20%, except for last year where it sat more than it moved and I changed it after 1 year. No AFM issues and TBH I didn't even know there were potential for issues until I had about 210k on it. I eventually got a Range device for it as a precaution but it saw less than 3k/9 months of use before I traded the Tahoe in, now it's just a paperweight on my desk.

DFM doesn't bother or scare me, I barely even notice it unless I'm looking for it. Although I do like hypermiling when taking long highway trips, or at least try to.

Greyhound6.2 · October 25, 2021

I saw a comment recently about putting the trans in L and limiting the gears to L9 to disable the DFM, I have been doing that for a couple weeks now I have no way of knowing if it actually disables the DFM but it does idle smoother being in L9. in normal D (auto stop disabled) when I come to a stop light the engine almost hesitates a bit and goes to slightly "rough idle" It has not done this since I started playing in L9