Has Mazda become a no go due to cylinder deactivation?

[t1snwrbrdr12]

Some long threads here about Mazda's with cylinder deactivation trashing their transmission. I struggled to accept, but it's clearly true.

Where do you find this info? Someone came here and said that before, but nobody seems to believe it.

I don’t lean one way or the other (at least pertaining to deactivation trashing the torque converters). But I do believe deactivation on a 4cylinder is ridiculous. Way too many complications to save the slightest bit of fuel.

 

[Nessism1]

Where do you find this info? Someone came here and said that before, but nobody seems to believe it.

I don’t lean one way or the other (at least pertaining to deactivation trashing the torque converters). But I do believe deactivation on a 4cylinder is ridiculous. Way too many complications to save the slightest bit of fuel.

Search "cylinder deactivation" and you will get lots of hits, many about Mazda. Here is one...

L

Thread 'Mazda TSB: 2.5L with CD & 6AT… 3, 6, CX-5, CX-30 owners get in here'

Jun 1, 2024

So, I’m in the market for a newer vehicle and came across this TSB while looking at Mazda recommendations:

https://static.nhtsa.gov/odi/tsbs/2023/MC-10244672-0001.pdf

From this thread:

https://mazdas247.com/forum/t/cx-5-...-on-3-4-upshift-bulletin-05-005-23.123880149/

APPLICABLE MODEL(S)/VINS

NOTE: Vehicles with cylinder deaction have a "M" as the 8th digit in the VIN for the 2.5L with cylinder deactivation.
2017-2024 CX-5 (2.5L with cylinder deactivation and 6AT)
2018-2021 Mazda6 (2.5L with cylinder deactivation and 6AT)
2019-2024 Mazda3...

• ltslimjim
• Replies: 37
• Forum: Automotive General Topics

• 

 

[Al]

I gave upon cylinder deactivation when my Dad's Caddy with the infamous 4-6-8 V8 grenaded 42 years ago leaving us stranded in Scranton, Pa..

Did you sell it to the Flintstones?

 

[zzyzzx]

How difficult is the cylinder deactivation to disable on these Mazda's?
At this point I'd probably just get a Trax.

 

[zzyzzx]

According to Reddit, you can unplug something in the engine and you will have no cylinder deactiviation. You will get an engine light. Possibly no light if you put an appropriately sized electronics component across whatever you unplugged.

 

[IndyIan]

According to Reddit, you can unplug something in the engine and you will have no cylinder deactiviation. You will get an engine light. Possibly no light if you put an appropriately sized electronics component across whatever you unplugged.

I would have no problem doing this on a car out of warranty, but I'd like to keep the warranty on a new car. Maybe there is a sport mode or something that disables cyl deactivation? I would use that some of the time.
I'm sure Mazda's system won't wreck the motor if used rarely. I think its a problem for long hwy trips in flat terrain where the engine has to work relatively hard in 2 cyl mode for long durations where you could run into trouble, as its effectively almost lugging the engine.
If the OP does mostly urban/suburban miles with lots of speed changes, I doubt the system is used enough to matter or damage anything.

 

[Frankrank]

Did you sell it to the Flintstones?

He had the engine replaced with a used one that removed the cylinder deactivation. Worked great until he sold it.

 

[Elkins45]

My issue isn’t with the existence of cylinder deactivation itself, it’s with the presence of the additional mechanical complexity needed to make it happen. Disabling it in software doesn’t remove the extra pieces parts just waiting to break.

Does anyone here know what actually happens under the valve cover to actuate the deactivation? What’s the mechanism?

Also, is it always the same two cylinders that remain active or does the system alternate them to distribute the wear?

 

[rijndael]

Disabling it in software doesn’t remove the extra pieces parts just waiting to break.

True. But in some cases, like the Honda J35, deactivating it is almost as good as if it never existed, since there really aren't any problems with the engines that never had it used with any substantial time. It's not like a GM v8 DoD/AFM issue where the lifters collapsed with normal use.

 

[goblin]

My issue isn’t with the existence of cylinder deactivation itself, it’s with the presence of the additional mechanical complexity needed to make it happen. Disabling it in software doesn’t remove the extra pieces parts just waiting to break.

Does anyone here know what actually happens under the valve cover to actuate the deactivation? What’s the mechanism?

Also, is it always the same two cylinders that remain active or does the system alternate them to distribute the wear?

Deactivation should be all electronic. There shouldn't be any mechanical add-ons other than the vibration dampening thingie mentioned in the Mazda thread linked above.

And that one should get under load only when deactivation is enabled.

The pairs of cylinders in play will definitely be alternated, possibly cycled every x-amount of time.

 

[Elkins45]

Deactivation should be all electronic. There shouldn't be any mechanical add-ons other than the vibration dampening thingie mentioned in the Mazda thread linked above.

And that one should get under load only when deactivation is enabled.

The pairs of cylinders in play will definitely be alternated, possibly cycled every x-amount of time.

How do they electronically decouple the lifters from the cam?

 

[rijndael]

I believe this video shows it:

 

[barryh]

I'm sure Mazda's system won't wreck the motor if used rarely. I think its a problem for long hwy trips in flat terrain where the engine has to work relatively hard in 2 cyl mode for long durations where you could run into trouble, as its effectively almost lugging the engine.

On my 4 cylinder VW there is not a chance of the engine working relatively hard in 2 cylinder mode. It immediately resumes 4 cylinder operation when anything more than a light load is applied. Basically 2 cylinder mode only switches in at a steady cruise on flat roads and it won't engage until a certain RPM is reached so there is no risk of lugging. Like everything else on modern engines all this will be controlled by an algorithm including adjustments to ignition timing, valve timing and throttle position to smooth the transition.

 

[Eddie]

My CX5 non-turbo 2022 has deactivation. However; a ~ 40mph+ on flat road the engine operates on 4 cylinders.

 

[F150]

I have a 2023 CX50 with cylinder deactivation. From what I see on the monitor, it rarely works; there is just not enough power to keep it engaged.

 

[Reggaemon]

Mazda sport mode will deactivate the 2 cyl. mode but it's not a useable fix. The transmission holds gears way too long in normal driving and it will not shift into the highest gear. It feels like your driving around in third gear all the time.

 

[Elkins45]

I believe this video shows it:

That’s not as intrusive as I feared.

There was something in their marketing about designing the transmission to cope with CD by adding a fulcrum. I found that confusing, but then again I don’t understand a lot about what happens inside an automatic transmission.

 

[GaryMX5]

I would have no problem doing this on a car out of warranty, but I'd like to keep the warranty on a new car. Maybe there is a sport mode or something that disables cyl deactivation? I would use that some of the time.
I'm sure Mazda's system won't wreck the motor if used rarely. I think its a problem for long hwy trips in flat terrain where the engine has to work relatively hard in 2 cyl mode for long durations where you could run into trouble, as its effectively almost lugging the engine.
If the OP does mostly urban/suburban miles with lots of speed changes, I doubt the system is used enough to matter or damage anything.

I have a 25 cx30. I can feel the cylinder deactivation system when it reactivates. You almost have to be concentrating on it to really feel it. For the most part I feel it when the car pulls hill or when I add a little acceleration while in cruise control. I rarely feel it on flat terrain. The best explanation is that it feels like a very subtle single engine miss.

 

[OneLonelyBurrito]

My issue isn’t with the existence of cylinder deactivation itself, it’s with the presence of the additional mechanical complexity needed to make it happen. Disabling it in software doesn’t remove the extra pieces parts just waiting to break.

Does anyone here know what actually happens under the valve cover to actuate the deactivation? What’s the mechanism?

Also, is it always the same two cylinders that remain active or does the system alternate them to distribute the wear?

Here is a diagram of it mechanism.

 

[JavierH19]

I would have no problem doing this on a car out of warranty, but I'd like to keep the warranty on a new car. Maybe there is a sport mode or something that disables cyl deactivation? I would use that some of the time.
I'm sure Mazda's system won't wreck the motor if used rarely. I think its a problem for long hwy trips in flat terrain where the engine has to work relatively hard in 2 cyl mode for long durations where you could run into trouble, as its effectively almost lugging the engine.
If the OP does mostly urban/suburban miles with lots of speed changes, I doubt the system is used enough to matter or damage anything.

Do it when it's off and when anything happens undo what you did while it's off to appease the stealer. Computer would be none the wiser.