BREAKING: GM is officially recalling the L87

[KMeloney]

Yup, impossibly stupid just 1 cylinder!! And not just the same 1 cylinder every time, it jumps around, but unclear really how random it could be.

I have also seen reference to running on 2 cylinders.

So you tell me what this means "but DFM actively turns off any number of cylinders in a variety of combinations"

There is not as much information out there about 100% how the DFM operates other than is has like 17 different operation modes.

I do know for sure that under DFCO (Decel with Fuel Cutoff) they do seem to shut all cylinders down with DFM, or at least in some order this does occur because I have watch the cylinder deactivation counts.

DFM Operation

DFM Overview

I didn't see in my quick review of those articles (thanks for them, btw) where the engine could operate on as low as 1 cylinder. Do you have something else that states this? I get that AFM was either 4 or 8, but I don't see where DFM can be as little as one. I'd think that there would always be at least 2 (opposing) cylinders activated at all times... But that's me trying to think logically.

 

[e2360]

Time for an oil analysis so you can have results back to take when they do an "Inspection" Metal levels may be beneficial if wanting a replacement or challenge their"inspection".

 

[jfoj]

By the way, where did you get the information about the constant load on the engine in the city of 70-80%? Here is the load schedule, I am now driving around the city in the mode of 10-20-30 miles per hour. 70% is the peak when I accelerated a little, and so the average load is 25-30%
When you release the gas pedal, the engine stops supplying fuel to the cylinders at all, haha, you confuse DFM work with forced idling, or this is known as coasting. This was done on carburetor engines)))

Maybe you did not follow all the info I provided or if you needed to translate it did not come over correctly. I have NEVER indicated the engine was operating at 70%+ load in the city, non of my graphs I have posted showed this. All the 70%-100% loading was done on at highway speeds primarily in 10th gear, sometimes in 9th when the transmission downshifts. This is usually when pulling very slight to mild grades, nothing steep at all.

These seem to also be the typically conditions when these engines have failed/locked up as well, almost always traveling somewhere between 60-75 MPH from all the reports I have seen.

As for the tool you are using, based on its format and size I really do not think you have the ability for that tool to actually monitor cylinder deactivation. More advanced tools will show what cylinders are active/deactivated and will also typically give a running counter of how many times each cylinder has been deactivated. I think the running counter is actually stored in the ECM, the tool just has the ability to display these values.

I am not confusing DFM with what you refer to as forced coasting. I am quite familiar with DFCO (Decel With Fuel Cutoff), this typically turns off the fuel injectors and sometimes the ignition coils. This has been going one for probably 30+ years, nothing new about that. I am sure your tool can show you this, but in addition to DFCO it appears for some reason DFM also collapses the lifters during DFCO as well or at least under some conditions.

Not sure if this was done on the AFM vehicles, never spent much time with these. Prior to cylinder deactivation on any manufacturers platforms, DFCO was used, may have tweaked cam timing a bit if that capability was available, but each manufacturer would implement some form of DFCO how they saw fit. Sometime even transmission control could also be implemented. Depends if the manufacturer expects as full of a coast mode or if they want to introduce any engine braking.

Lots and lots of moving parts, probably too many moving parts. All this extra crap does nothing for the end users as far as reliability, it just costs us a lot of money and down time when it fails. AFM and DFM or any cylinder deactivation was never intended for performance and if the engineers thought it would help reliability they were clearly confused.

 

[jfoj]

I didn't see in my quick review of those articles (thanks for them, btw) where the engine could operate on as low as 1 cylinder. Do you have something else that states this? I get that AFM was either 4 or 8, but I don't see where DFM can be as little as one. I'd think that there would always be at least 2 (opposing) cylinders activated at all times... But that's me trying to think logically.

Now just think about what is going on with the rotating engine mass when all the magic is happening. What is going on with the crankshaft torsional twist, crankshaft fore and aft loading, changes in bearing loading. It just is not an ideal situation and it is really not needed. At least with AFM, you had 4-6-8 cylinder behavior, and always the same cylinders, far more balanced and less chaotic.

We all were provided AFM/DFM for the sole reason to meet some arbitrary government standard that made in a dark corner with little to no input from people that have technical experience.

Non technical politicians and bureaucrats making technical decisions will not end well. We are all victims of this mess.

 

[NoYukonYet_1Jeep]

Trying to keep up here. I’m on my 2nd 2023 yukon Denali 6.2L. First one blew the motor at 3600 miles. Did full vehicle replacement. 2nd one has 32k on it and at the (Chevy) dealer right now for oil change. They pulled my codes and I have the loss of propulsion L87 one (see pic) but not the P0016 ppl were referencing. Took a stab at requesting 0w-40 but they wanted to charge close to double so I didn’t throw a fuss. Praying at this point my vehicle doesn’t get marked as condemned and unable to leave the dealer after they swap my oil. Godspeed my fellow 6.2 liters

 

[DanielAndVictoria]

I have a 2022 High Country with about 57k miles. About 3 weeks ago while I was doing about 75 miles an hour on the highway. I heard a little clicking noise. Then the engine just completely died and I was forced to coast over to the median. Car would not restart at all. Thought it was an alternator issue at first. But now we know what the real culprit is. I had complete engine failure. Luckily it will get replaced under the power train warranty regardless. The stupid thing is they told me it would be at least eight weeks before they can even look at the vehicle. And they don’t even offer a loaner vehicle or a rental. Even though they’re replacing this under warranty. Now I don’t care because I have two other vehicles. But this is a major issue for people That this is their primary vehicle and they’re still making payments on it.

 

[jfoj]

Trying to keep up here. I’m on my 2nd 2023 yukon Denali 6.2L. First one blew the motor at 3600 miles. Did full vehicle replacement. 2nd one has 32k on it and at the (Chevy) dealer right now for oil change. They pulled my codes and I have the loss of propulsion L87 one (see pic) but not the P0016 ppl were referencing. Took a stab at requesting 0w-40 but they wanted to charge close to double so I didn’t throw a fuss. Praying at this point my vehicle doesn’t get marked as condemned and unable to leave the dealer after they swap my oil. Godspeed my fellow 6.2 liters

Your vehicle has clearly been recalled and should have the 0W40 oil. The Service Advisor probably does not know this. The dealer will not likely hold your vehicle unless they see a Pending P0016 code. I have seen few cases of a P0016 code before an engine failure.

The remedy not available means they most likely do not have the 0W40 oil fill cap, but they may.

 

[NoYukonYet_1Jeep]

Your vehicle has clearly been recalled and should have the 0W40 oil. The Service Advisor probably does not know this. The dealer will not likely hold your vehicle unless they see a Pending P0016 code. I have seen few cases of a P0016 code before an engine failure.

The remedy not available means they most likely do not have the 0W40 oil fill cap, but they may.

I considered going to an alternate service(external to GM) location and requesting the 0W – 40, or even bringing my own, but I thought that might have an impact on the warranty since they then could not verify that the oil change took place. My opinion was I’ve been running it for 32,000 miles with 0W – 20 and we haven’t died yet. So what’s another few thousand miles. More or less just waiting to see how this all unfolds with the recall. I need my car. I hope that GM is setting up a fleet of loaner vehicles. I wouldn’t mind testing out one of those Silverado EV‘s to be honest.GM.. if you’re listening ..

 

[NoYukonYet_1Jeep]

I have a 2022 High Country with about 57k miles. About 3 weeks ago while I was doing about 75 miles an hour on the highway. I heard a little clicking noise. Then the engine just completely died and I was forced to coast over to the median. Car would not restart at all. Thought it was an alternator issue at first. But now we know what the real culprit is. I had complete engine failure. Luckily it will get replaced under the power train warranty regardless. The stupid thing is they told me it would be at least eight weeks before they can even look at the vehicle. And they don’t even offer a loaner vehicle or a rental. Even though they’re replacing this under warranty. Now I don’t care because I have two other vehicles. But this is a major issue for people That this is their primary vehicle and they’re still making payments on it.

The story is all too familiar. It’s pretty sad that I’m actually impressed You made it to 57,000 miles. I didn’t even make it to 4K . What a nightmare / joke of a scenario. Good luck with the motor swap

 

[jfoj]

I considered going to an alternate service(external to GM) location and requesting the 0W – 40, or even bringing my own, but I thought that might have an impact on the warranty since they then could not verify that the oil change took place. My opinion was I’ve been running it for 32,000 miles with 0W – 20 and we haven’t died yet. So what’s another few thousand miles. More or less just waiting to see how this all unfolds with the recall. I need my car. I hope that GM is setting up a fleet of loaner vehicles. I wouldn’t mind testing out one of those Silverado EV‘s to be honest.GM.. if you’re listening ..

Fresh 0W20 would be better than oil with 5k+ miles on it. To be honest I have no interest in allowing my OLM to go below 50%.

For the recall, all that is needed is for the dealer to check for a P0016 code, I think remove the oil filter and cut it open to look for metal, then if no code or metal, put OW40 in the engine, install a new oil filter and put an oil cap that has 0W40 printed on it. Pretty simple, but maybe GM has not provided the dealer info on cars that are not in inventory?