I have a 2023 CX-5 regular engine.
Question about when this functionality is supposed to happen. I would guess engine would reduce from 4 to 2 cylinders when driver is cruising, perhaps on hwy using cruise control. However, when i turn on the dash screen monitor to show the status of the feature (Information > Fuel Efficiency ...), I see the status symbol indicating a change from 4 to 2 and back to 4 repeatedly while driving in city. It seems to deactivate/reactivate much too often. Anyone have input to share on when theirs deactivates? I hope this is NOT a malfunction.


Thanks all

 

Well a CD question - I will first say I have a 23 cx5 approaching 30k miles - Its less than 18 months old so I been taking some road trips - long ones -1500-3000 miles per - I looked into CD function very closely and the fact it goes 4-2-4-2 is normal - If you are not watching the monitor then you should not notice ANY transition blips or power interruption - its seamless/ really quite amazing - and Ive been on long stretches of wide open plains for hours and can get over 45mpg if flat or slightly downhill and save tons of fuel - Many times over 500 -550 miles on one tank (15.3) gallons but gasing up before empty so about 14.5 gallons---- Its amazing for a 4000lb+ AWD vehicle that scoots at 75-80 doing this effortlessly. at about 2750 rpms -at a good power delivery spot for any acceleration- - There were some minor issues with CD back in the 18-21 yrs - only a few - but Mazda retweaked it and 90% of the fleet has it from 22-early 24 on 2.5 NAs - Although they did discontinue it and i-stop in late 23 production , early 24 back, and on top trims only in 25- Its costly to add and there apparently was a parts shortage / so in 2025 you need to go Premium Plus or Carbon Edition NA to get it ---Monrone sticker showing average MPG city/fwy at 28 -----the outboard 2 cylinders get fuel cut but pistons keep pumping and lubricating - as well hydraulic valve adaptors stop valves until they reactivate - CD will never operate in PARK , NEUTRAL or REVERSE - As well the PCM senses speed and power needed to keep that going - and if it can will default to the 2 center pistons driving and 2 outboard no combustion . Another way to disable it is getting up to higher speeds and once there sufficient torque needed to propel the 5 at that a minimum torque prevents deactivation - example - If I go out of Grand Junction( Co) headed to say Vegas - speed limit is 80 - on I-70 you can be pretty sure that going over 75-90 it will not reduce cylinders- if on a grade Ive never seen it kick in anywhere at or over 3000- rpms - if its slower - flat 60-75 use 5th gear and at or above 3k rpms - no deactivation and strangely this engine does well at elevated rpm on gas mileage in 5th - So dont trip - just road trip - Im calculating savings of easily $1000 in fuel since new - just due to CD riding at about 75=80 --and do regular oil changes at 3Kmi - flat - it can stay on if you learn its threshold - I love it - and its reliable -,so far dont know how to disable -,but rest assured - its a software change and someone will defeat - I also suspect that if theres any fault it will default to no CD - which is a guess only -.I would wait until after the drivetrain warranty is gone - but im liking it -,- In city driving I would use manual mode w/ paddles keep rpms over 3 k - no CD= or just drive it and dont worry --ITs a CX5 after all

 

Great information!
Thanks for all of it.

 

I don't think CD is discontinued. I was just offered a 2025 Mazda CX-5 GS CD AWD 6AT last week to replace my 2019 CX5 CD. I didn't notice any difference driving my 2019 CD but I only get 600 km per 47L fill up ( 373 miles per 12.4 US Gallon fill up) How are you getting 600 Miles?

 

I know there were lots of cars without the cylinder deactivation due parts shortages. I forget the exact way to tell, but it's by looking at the VIN number.

 

That's still happening. At my local Mazda dealer it's about a 80/20 split on the 2025s. Of the cars on lot or in transit 12 of them have cylinder deactivation, 4 of them do not have CD according to the online window stickers.

On my 2022 CD is totally smooth and seamless. If monitoring I can also see it switch back and forth from 4 to 2 and back to 4 sometimes as it decides how it wants to proceed. If I tap the accelerator when using 2 the switch back to 4 is never noticeable.

 

Hmm. if you go to the Mazda site they describe the higher trim levels - e.g., Premium Plus - as having CD, but not the lower trim levels. They also say the rated mpg for those cars is about 3mpg higher than those w/o CD. There is no footnote about parts shortages or anything else. So is the 80/20 split you are noting just a matter of trim level?

 

I'm a new Mazda owner of two 2022 CX-5 Premiums and so far I'm quite impressed.
So as long as we're on the CD discussion, I noticed that my cylinder deactivation monitor screen will go from 4 active to 2 active and then 0 active. In other words, all the cylinders in the graphic go dark. That would indicate that none are active. But how is this possible? Does the transmission torque converter keep the engine spinning even though there's no combustion happening? As soon as I touch the gas pedal, all four cylinders light up again.

Thanks!

 

Since the pistons are still working when deactivation occurs, I have to conclude that the valves are held open otherwise there would be an effect similar to a jake brake.
However, in the Mazda blurb and videos, they show that the lifters are deactivated and the valves stay shut.
Wouldn't the pistons be acting similar to an air compressor and thus using energy from the engine to compress the trapped air?

 

That would be my understanding. I see the issue of an open valve. If the exhaust is held open, you're injecting air into the exhaust flow vastly changing the amount of oxygen in the exhaust which is going to affect the emissions. If you hold the intake, you're pushing air into the intake plenum messing up the air/fuel ratio that's been determined by the air flow sensor. However I totally see your point as having two dead cylinders would make the engine run terrible one would think. In the past I've used the trick of pulling a spark plug wire to help find a misfire.

I need to do more research to figure this out.