I wish I could turn off cylinder deactivation

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Fredericton Canada
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2018 CX-5 GT
My understanding is that C.D. kicks in at less than 2000 RPM, and under 80 kph(50 mph), and will stay on unless you accelerate, come to a stop or go up an incline. It supposedly works best with cruise control set to speeds lower than 80 kph(50 mph). Is this correct?? If so I must try this and watch the "Current L/100km" readout on the center gauge, to see if I can notice the reading drop to indicate that C.D. has kicked in.
 
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CX5 GT
torque and rpm are the leading factors. CD can trigger at any rpm in the range.
speed is not relevant.
unless you have the monitor app in the infotainment (2020+ models) or OBDii tool, watching the fuel cinsumption is not very good indicator.

here is the cd range below
1CFD9A20-154C-4E63-8719-DD1B37DDE814.jpeg
 
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2019 CX5 Signature
Glad that I don’t have the stop/start or cylinder deactivation in my 2019 Signature, but I do have CD in our ‘19 Vette. Luckily we’re able to install a Range device (Range Technologies) in that car to prevent the CD from functioning.

Question…in the ‘vette we can also stop the CD from working by putting the transmission in manual mode and using the shift paddles. Can the CD be overridden in the Mazda by shifting similarly?
 
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CX5 GT
based on replies from people who have the monitor CD app in the infotainment, no.
I dont think CD is that much of an issue with the CX5 nowadays. There are hundreds of thousands of cars with it in the past 4 years. Except some issues initially I think Mazda has fixed pretty much what was found in the early models (2018- )
also there are lots of used cars with 100-150k miles already.
 

HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
based on replies from people who have the monitor CD app in the infotainment, no.
I dont think CD is that much of an issue with the CX5 nowadays. There are hundreds of thousands of cars with it in the past 4 years. Except some issues initially I think Mazda has fixed pretty much what was found in the early models (2018- )
also there are lots of used cars with 100-150k miles already.
torque and rpm are the leading factors. CD can trigger at any rpm in the range.
speed is not relevant.
unless you have the monitor app in the infotainment (2020+ models) or OBDii tool, watching the fuel cinsumption is not very good indicator.

here is the cd range below
View attachment 313250
CD has only been around since 2018. How many 2018 owners have been driving 25k - 37.5k miles per year? How about 2019 owners driving 33k - 50k miles per year? Not a lot. Frankly, I don't care what car it is or who made it, the long term longevity of a new generation or drivetrain or significant drivetrain modification requires a lot more than 4 years to assess.

Anyway, how fast do you think you'd have to be driving at 3500 rpm to achieve the relatively low load for CD activation in anything approximating a steady state? Quite fast I'd say, if possible at all, not anything I'd have occasion to test let alone drive any distance. I wonder where that chart came from. If that's from a lab test with no wind resistance it might not be possible at all in practice. If you want to say running up to 3600 RPM at any speed then easing of the gas can get it to drop into CD I'd have no reason to doubt that as RPMs drop to 3500.. Any kind of steady state at 3500 or even 3000 RPM? I'm not seeing it.

In fooling around with it the one constant I've found in getting to a steady CD deactivation, however brief, is light, steady gas pedal pressure at relatively low RPMs on a flat straight road. You have to work at it and in fairly short order gradual deceleration occurs.
My understanding is that C.D. kicks in at less than 2000 RPM, and under 80 kph(50 mph), and will stay on unless you accelerate, come to a stop or go up an incline. It supposedly works best with cruise control set to speeds lower than 80 kph(50 mph). Is this correct?? If so I must try this and watch the "Current L/100km" readout on the center gauge, to see if I can notice the reading drop to indicate that C.D. has kicked in.
As a practical matter you could see cylinder deactivation at expressway speeds with steady gas pedal pressure at relatively steady and low RPMs. You can't really maintain it over any distance. It seems the drag from wind and rolling resistance is the cause of gradual deceleration requiring you give it a little gas to get back to speed, knocking it out of CD mode.

I can't speak to cruise at 50 mph since I don't drive that way and I'm having a hard time envisioning where that would be both practical and safe. In my fooling around with CD the longest I was able to hold CD activation steady was at 50 mphs on a flat straight road for about a mile. After that I started to see gradual deceleration. If you can find a 50 mph flat road where it's safe to maintain that speed on cruise (no bends in the road with good visibility) without other drivers riding your bumper by all means give it a shot.

There's a reason why EPA highway mileage with CD buys you an extra 1 mpg. It's not something that can be maintained for any period of time. Sure, you can add a few more mpgs if you focus on it and milk it but who wants to drive like that except in some mpg competition.
 
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CX5 GT
Well if a person drives 12-13k per year on avg and keeps the car at least 10 yrs thats 120-130k. Not a problem for the engine if the car is maintained properly. And after 10 yrs or so we most likely would be forced to go EV anyway.

I think it buys more than 1mpg. I have seen 35-36 mpg quite often. This engine is most fuel efficient in the 50-65 miles per hour.l, steady speed and less torque. Using the cruise control is a very good option too.
Even the Turbo can go in the low 30s if driven in the range.

This is what I get almost always when driving within the speed limits - 35.8 for this trip
(my city mpg is in the 27-28 as well which is even more than the epa)
4C92772A-4EC5-4754-B3EB-435060E5572A.jpeg
 
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HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
Well if a person drives 12-13k per year on avg and keeps the car at least 10 yrs thats 120-130k. Not a problem for the engine if the car is maintained properly. And after 10 yrs or so we most likely would be forced to go EV anyway.

I think it buys more than 1mpg. I have seen 35-36 mpg quite often. This engine is most fuel efficient in the 50-65 miles per hour.l, steady speed and less torque. Using the cruise control is a very good option too.
Even the Turbo can go in the low 30s if driven in the range.

This is what I get almost always when driving within the speed limits - 35.8 for this trip
(my city mpg is in the 27-28 as well which is even more than the epa)
View attachment 313262
I averaged in the high 35's once over about that same distance, based on the trip data display, for no reason whatsoever. I topped the tank, drove about 8 miles to the expressway, then roughly 60-70 mphs, on a leg I've made many times. I'd never previously seen it above 34 under any circumstance and never since. By the end of the tank it gave me about what I would expect.

I don't trust the display. Doing manual checks I've seen it overstate by as much as 2.5 mpg, other times spot on. I've never seen a complete tank of all-expressway driving registering anything better than 33 on a manual check.

City traffic? It depends how you define that. If I was driving Uber in Manhattan all day (shoot me first) I'd probably be looking at mid-teens.

By the way, you should update your profile to show what model year you have.
 
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18 Mazda CX5 AW
I have a 2018 CX NA AWD

Based on actual measurement of tank and mileage, my highway mileage is usually between 32 and 37 mpg at speeds between 55 and 65 mph. The onboard display is usually pretty accurate, with maybe no more than 1 mpg difference of the actual useage.

My average mpg is only 25 to 26 mpg.

Idling during start and at drivethru's, flooring the gas during merge, air conditioning, and country hill driving all brings my average down.

Noticed that the gauge pegs at 80 mpg during downhill descent, and country drive is usually metered at 20 to 25 mpg(blue line). Acceleration is pegged between 9 mpg(quick acceleration) and 19 mpg(to bring back up to speed acceleration). And cruise control at highway speeds of 55 to 65 mph is needled at 35 to 45 mpg during long flat drives.

I therefore assume that cruise control is in CD mode at the 35 to 45 mpg range.

* My highest actual calculated mpg is 39 mpg with alot of 37 mpg days for highway/freeway only.
 
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2018 AWD GT Premium Red/Black
torque and rpm are the leading factors. CD can trigger at any rpm in the range.
speed is not relevant.
unless you have the monitor app in the infotainment (2020+ models) or OBDii tool, watching the fuel cinsumption is not very good indicator.

here is the cd range below
View attachment 313250
There are no units on the torque axis. Did those get cut off?
 

cx5boo333

2021 Cx5 GT AWD
CC93B19F-F7CE-4560-8737-59BD0724E8B9.jpeg

On a route where I could coast a lot yesterday my readout summarized it to be 43.6mpg, wow. I watched the CD screen part of the time and it only deactivated when I barely asked any power from it (55-70mph)
 

HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
First of all, FWD gets 1 mpg better than AWD, for 2020 anyway. For some posters I can't tell which they are talking about, but lets move on.

It is instructive to know how the EPA actually tests gas mileage:


Click on the chart for the highway mileage test. It runs 12.6 minutes, 10.3 miles, with an average speed of 48.3 mph without exceeding 60 mphs. However it begins from a stop and at the end drops from 60 to 0 over about 40 seconds implying braking. The various zigs and zags along the way imply some braking and acceleration.

This is more typical of the rural two-lane driving in light traffic I frequently do--the 30 mph drop through a village, occasional light braking then reacceleration when a vehicle in front is turning. Lo and behold, I get right around the EPA rated 30 mpgs for those drives, sometimes a little better depending on circumstances.

So, if you enter an off rush hour urban expressway without hills with a 50 or 55 mph speed limit, reset the mpg display, and then are able to hold at the speed limit with no braking, cruise or otherwise, I'm sure it is possible to see significant improvement over the rated 30 mpgs for AWD or 31 mpgs for FWD. Thinking back now to when I lived in a very rural area (the county had no stops lights) there were stretches of straight, flat two lane road with no stops for 10 miles and a 55 mph limit, so there is that possibility.

But that's cheating. In the real world you start from a stop somewhere, drive some ways on surface roads, and then giddy up. The optimal real world conditions would be gassing up at a tollway service center, accelerate to highway speed over something less than a mile, and then cruise for some hundreds of miles before exiting right into another service center to refill.

I'm with @IamVAguy. My more typical expressway scenario is 55-65 speed limits doing 62-72 mph yielding 32-33 when the traffic is free flowing. That's when tanking up, entering the expressway, and driving 200 miles before stopping. That would be consistent with the EPA 30 rating--little or no braking and reacceleration that we see in the EPA cycle more than compensates for the higher speed.

But here is the question: pre-2018 versions without CD would also see significant improvement over the EPA rating under the more favorable or optimal conditions described above in comparison to the EPA cycle. So what does it really buy us?
 
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HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
Then there's the EPA urban (aka "city" cycle):


First there's that run up to 60 mph which is a little bizarre for what we would normally think of as urban. The stops average about every 0.4 miles which seems reasonable for light-to-average urban traffic-- you hit some lights and some you don't. But the idle times are mostly very brief, with several stops amounting to virtually no idle time at all. 7.45 miles over 23 minutes? That's more like suburban rush hour or urban off hours.

Now, if it's 2:00 AM in an urban area with few cars on the road, you could probably do better than the city rating. In rush hour? A lot worse.
 
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HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
On a route where I could coast a lot yesterday....
As an FYI, if you are not already aware, when coasting (foot all the way off the gas), the cylinder deactivation display should show no cylinders operating. That's typical of modern fuel injected engines and not an aspect of the Mazda cylinder deactivation we're discussing here.

The term "cylinder deactivation" as applied to the 2 cylinder operation of this vehicle is something of a misnomer in a couple of respects. First, to repeat, 4 cylinder deactivation when coasting is typical with EFI. Second, all 4 cylinders are always in motion. Deactivation as it pertains to this Mazda engine closes the values and suspends fuel injection to 2 cylinders under the right conditions. Some other makers' engines that "deactivate" some cylinders operate the same way, maybe all of them, I couldn't say, though it strikes me now that suspending cylinder motion would be a very complex design without any benefit I can think of while creating more engine vibration.

This is old hat to many around here but something new to me with this vehicle since I had never previously considered buying a vehicle with a CD feature. In differentiating this engine from the same engine pre-2018 without CD, the tech would be better called "2 cylinder deactivation", or better yet, but too clumsy, "2 cylinder injection deactivation."

Mazda also added a fulcrum to the transmission to reduce vibration in 2 cylinder mode.

That's all old hat or TMI for some, informative for others, I suppose.
 
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erhayes

Contributor
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2022CX5 PP
ON my 2022 PP I've determined that at ~ 50 MPH steady cruise, on level is the switch over from 2 to 4 Cylinders.
 

HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
I stuck the wrong link in my last post which I have now deleted. Here's the one I intended. Some may find this one informative:


The video seems to suggest that in 2 cylinder mode injection switches to a higher pressure mode, not a general characteristic for 2018.
 
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ColoradoDriver

Gen-1 Kodo Design
Contributor
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Denver, CO
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2014 CX-5 Touring
I wonder how much fuel is save with these 4 to 2 returns to 4 Maybe 0.01 gal per 100 miles. This quest for fuel savings via Government is making life more complicated for sure.
Tell me about it. My nephew has I think a 2019 with CD and had to get warranty work done on it as something broke and put it in limp mode. I don't recall the details, but was related to the cylinders.

If something happens to my 2014, not sure what I am going to do. I do not like the newer gens of CX-5's at all, and this is one example why besides the superficial.
 

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