Thanks for everyone's input. Seems like some had really bad experiences and others a wonderful experience. I guess when ever i buy another vehicle ill see if it has it and if it's worth using..
Cylinder deactivation?
- Thread starter mpack88
- Start date
- Status
AZjeff
$50 Site Donor 2023
Disabling it with a tune of some sort is kind of a bandaid, the parts are still in the engine. It seems best practice is good oil and conservative OCIs.
It's not only additional parts that can fail, it is the types of failures.
So on Chevrolet, the way the system works is that there are solenoids that alter the oil pressure on 4 of the 8 cylinders, eventually what happens is that the lifters fail. Sometimes for no reason at all even if you have followed the manufacturer's recommended OCI's.
So on Chevrolet, the way the system works is that there are solenoids that alter the oil pressure on 4 of the 8 cylinders, eventually what happens is that the lifters fail. Sometimes for no reason at all even if you have followed the manufacturer's recommended OCI's.
The new thought from numerous teardowns is the plastic lifter tray design being the biggest weakpoint. It allows the lifters to rotate in place and crunch...byeeeeeeee.
Even the new DFM has been destroying lifters. One guy with a new 2020 GMC AT4 with like 4500 miles had to get new lifters/other stuff.
I did some reading and quickly confirmed that you are right. What is perplexing to me is that the 'eco' light can go on and off under moderate load, and the transition is transparent to me. I assumed (wrongly) that this was a 6 cylinder mode. With the 'eco' already on, and starting down a slight grade, or slowing down a bit, the engine seemingly switches modes again to 4 cyl mode, and runs with an annoying rumble and light vibration. If I press the accelerator a bit, it will kick (with a bit of a clunk) out of that mode and back to being smooth, with the 'eco' light still on. I thought I had it figured out, but I need to do some more research.
Edited to add; 'MDS and the ECO light are not tied together. You can get the ECO light on when in 8 cyl mode and you can tell when MDS is on by the sound and feel.' Found several posts similar to this one on various forums. Makes sense now.
Last edited:
Cylinder deactivation, start/stop, and CVT transmissions. The unholy trinity for many BITOGers, including me.
I have a ‘15 GMC Sierra with cylinder deactivation (8 to 4) and I can’t tell when it happens without looking at the instrument panel display. It has the 6.2L. OTOH, I can definitely feel the start/stop on my ‘19 VW GTI. It tends to shudder a bit on shut down.
My 21 Camaro SS has it and it's flawless to transition. I never even know when it drops four cylinders unless I look down at the display. Only occurs in cruise at constant RPM. When you floor it, the car instantly reacts with no lag I can tell. I was worried it may bog down or shudder in and out of the 4 cylinder mode, but thankfully not an issue.
Long term, who knows what it may influence reliability wise. But given this tech isn't really new at this point, I assume they got it worked out. Feels like they do, at least. Its tuned very well.
Just my experience though... I'm far more annoyed by rental cars I've driven that shut off at red lights (non hybrids). That is a horrid feature that just feels clunky and unrefined. Can't stand it!
Long term, who knows what it may influence reliability wise. But given this tech isn't really new at this point, I assume they got it worked out. Feels like they do, at least. Its tuned very well.
Just my experience though... I'm far more annoyed by rental cars I've driven that shut off at red lights (non hybrids). That is a horrid feature that just feels clunky and unrefined. Can't stand it!
Ah, go to Mazda3Revolution and see if Mazda owners complain about CD - Cylinder Deactivation. A sizable number of owners of the 3 DO have very significant prbs with it. There is a fix - different rad-mounts and reprogramming that mitigates the issue, though not 100% of the time. I personally have zero use for it; it is an engineering abomination.
JTK
$100 Site Donor 2025
I've experimented with MDS on and off over full tanks of fuel on my 2019 Ram 1500 classic. It's about a 10% fuel economy gain with it with my usage, but I do a lot of light highway travel.
It is super annoying at lower speed driving, especially with hills involved.
Like said above, I just toggle it off during those conditions. It's amazing the amount of Ram 1500 owners I've spoken with that never knew you can do that.
For sure I'll take cyl deactivation over start/stop, but I don't think we'll have a choice as time goes on. They'll all be DI, start/stop w/cylinder deactivation and have 10speeds or CVT.
It is super annoying at lower speed driving, especially with hills involved.
Like said above, I just toggle it off during those conditions. It's amazing the amount of Ram 1500 owners I've spoken with that never knew you can do that.
For sure I'll take cyl deactivation over start/stop, but I don't think we'll have a choice as time goes on. They'll all be DI, start/stop w/cylinder deactivation and have 10speeds or CVT.
- Joined
- Dec 28, 2014
- Messages
- 3,001
Yes, and quite honestly it’s very much hit or miss with the GM’s. There’s threads a mile long on the truck forums, yet there is an equal number (or more) that never have an issue with the lifters collapsing. The transmissions are a different story - they have a real problem there - the torque converters can’t seem to handle the constant shifting back and forth to accommodate the V4-V8 switching.
- Joined
- Dec 28, 2014
- Messages
- 3,001
There’s a little pin inside the lifter, when it comes out it must engage a little “ramp” or grove inside the lifter. When that ramp/grove wears away, the linter stays collapsed.The new thought from numerous teardowns is the plastic lifter tray design being the biggest weakpoint. It allows the lifters to rotate in place and crunch...byeeeeeeee.
Even the new DFM has been destroying lifters. One guy with a new 2020 GMC AT4 with like 4500 miles had to get new lifters/other stuff.
Quite honestly I hear there are a couple reasons why this will fail...infrequent oil changes, low oil level...but what is most discerning...frequent use of the AFM system (easy responsible driving, causing it to frequently engage V4 mode). Ouch. There is also a little mesh screen on the VLOM that can get clogged (because of infrequent oil changes). Some people change that screen out every so often. I swear the people who never have a problem on these trucks beat the crap out of them and don’t even realize they have cylinder shut off.
The V6 Chevy trucks with the cylinder deactivation are much smoother...they activate V4 mode half as less. It’s actually (in my opinion) a much smoother and enjoyable driving experience.
4WD
$50 site donor 2025
Well, I will say again our 5.3/6L is smooth as silk and it would be very hard for a V6 to be a more enjoyable driving experience in a 4WD Tahoe …
I have driven many miles with the display on because otherwise you will not know the mode. In town there is only one road it does V4 on and that’s at 50 mph and low RPM. On the interstate - anything north of 70 it’s V8 … Speed limit is 75 and you need to do that or be ran over
I have driven many miles with the display on because otherwise you will not know the mode. In town there is only one road it does V4 on and that’s at 50 mph and low RPM. On the interstate - anything north of 70 it’s V8 … Speed limit is 75 and you need to do that or be ran over
Last edited:
4WD
$50 site donor 2025
I noticed on my Chevy rent cars you can select N and the engine stays on. With my new Jeep … that S/S override will be the 1st button with the paint wore off. There are some black box fixes … not cheap for now
I agree with you but some time ago I read a review of Honda VCM in the Odyssey that stated these motors got almost 18 % mpg better than the Toyota equivalent. Not minimal. Don't know accurate this is. Just saying..
4WD
$50 site donor 2025
Well … folks like CAFE bashing here … but it’s not going away because “help is on the way” …
I did not ask for any of this … but if it helps keep vehicle choices like they are longer, deal with it.
For me to “proactively“ have a perfectly good engine torn apart to remove gremlins can’t be drastically cheaper than doing all that after it fails.
Same thing on my '16 Tahoe with the 5.3.
Whyn would it change the world?
- Status
Similar threads
