Disable Cylinder Deactivation

HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
I can't feel the transition from 4 to 2 or 2 back to 4. I can assume when it changes, when the load is light, I just can't detect it.
It also goes to zero cylinders. In every test scenario I've performed it kicks to zero cylinders from two or four when taking my foot all the way off the gas--coasting--so long as I'm going over 10 mph.

It may also go to zero cylinders at cruising speed when holding the gas steady or easing off. Possibly I'm feeling I'm holding steady but the system detects a slight easing.

Upon further review I have detected one scenario where the transition is not seamless. Since the system always runs four cylinders under 10 mph and zero when coasting, when coasting down through that threshold there is a slight jerk, akin to a downshift, as it goes from zero to four. I don't think this is something many folks do very often outside a test scenario. Braking while crossing the 10 mph threshold mutes the affect.
 
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HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
Are you sure all cylinders stop firing? Only two are set up to deactivate.
That's what the cylinder deactivation display shows in my US 2020 CX-5 Touring AWD 2.5L gasoline version under the conditions already explained. And when the display shows zero cylinders firing the real time MPG gauge confirms it, burying the needle at 80 MPG.

So, either all cylinders stop firing under the explained conditions or Mazda is perpetrating an elaborate ruse with their displays and gauges. I think it's the former.
CD is designed to work between 25 to 50mph.
As explained I'd have to say that is incorrect, at least in my vehicle as explained earlier.

Maybe somebody who has this 2.5L engine in a 2020 with the display and gauge will get around to confirming what I've been saying. From what I'm reading from other posters evidently not all Gen 2 versions have the cylinder deactivation display and maybe not the real time MPG guage in the right instrument pod for all I know.
 
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Mazda
At 15:45, when the reviewer opens up the fuel economy app, it looks like what all our vehicles have, a generic fuel economy measurement that is not in real-time and indicative of CD activation. Any MPG increases during a particular time interval is purely coincidental because certain criteria must be met before CD will activate.

If you want to have a real-time CD monitoring system, it's present on all 2019+ Mazda 3 models and on the 2021 CX5,

https://www.reddit.com/r/mazda3/comments/bkaa0g
 

HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
At 15:45, when the reviewer opens up the fuel economy app, it looks like what all our vehicles have, a generic fuel economy measurement that is not in real-time....
Just to be clear, that reviewer is driving the GTR with the turbo engine. Other posters repeatedly comment that this engine does not have cylinder deactivation.

As I said a couple of times, the real time MPG monitor in my vehicle (US 2020 Touring AWD 2.5L gasoline) is not a touch screen function. It is in one of the display options in the right pod of the instrument cluster. That pod has four display option. You hit "Info" on the steering wheel until you get to this display:

1602511103262.png

The gauge at the top of the display is buried at zero in this picture because the vehicle is running in park where you get zero mpg. I will not be taking video while driving. I can assure you that as the vehicle is driven that guage bounces around in real time in sync with the cylinder deactivation display. That mpg gauge can be used in lieu of the cylinder deactivation gauge if you have some other use for the screen once you know what to look for which I covered previously.

In my vehicle the cylinder deactivation monitor is displayed on the touch screen by going to Applications > Fuel Economy Monitor, not "Information > Fuel Economy Monitor" as stated by the guy you quoted who has a 2019 Mazda 3. That screen display in my vehicle looks like this:

1602512030630.png


With the engine running and the car in park, the display shows all cylinders firing. As stated earlier, my tests show this is always the case under 10 mph.

Why would it not work above 50 mph? Seems redundant if that's the case.
Wouldn't you want to have it working at highway cruise speeds?
Right. It does work at highway speeds and will go to two or zero cylinders when highway cruising under circumstances previously described unless Mazda's gauges and displays are lying. Whether there is a top end speed where cylinder deactivation is no longer applied I could not say. 75 mph is about as fast as I've been going while testing this stuff out. My guess is if you ran this thing to top speed, whatever that is, then let all the way off the gas into coast, all four cylinders would stop firing at 100+ mph.

I cannot attest to how Mazda has rejiggered gauges and displays from one model to another, one year to another, one market to another, one software update to another. But I think it is fair to say anybody with a US 2020 CX-5 2.5L with current software could reproduce my results.
 
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2010 CX-9 GT
I think most cars on the road stop injecting fuel when you are coasting down or engine braking. That's not really cylinder deactivation, it's just a benefit of electronic fuel injection. When the display says zero cylinders it's just not injecting fuel because there is no load on the engine.
 
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HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
I think most cars on the road stop injecting fuel when you are coasting down or engine breaking. That's not really cylinder deactivation, it's just a benefit of electronic fuel injection. When the display says zero cylinders it's just not injecting fuel because there is no load on the engine.
I don't think so and I'll tell you why.

First, I'm looking at a "cylinder deactivation" display that shows no cylinders active under certain condition. So, the display would have to be lying.

More importantly, the display will show zero cylinders (with the real time mpg gauge jumping to and buried at 80) in situations other than outright coasting. If you are highway cruising and let off the gas enough but not all the way, you can see zero cylinders displayed and mpg buried at 80.

I think I'll stop talking about this until somebody else actually does some testing in a model with the same display features. It's pretty easy to do.
 
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2010 CX-9 GT
I don't think so and I'll tell you why.

First, I'm looking at a "cylinder deactivation" display that shows no cylinders active under certain condition. So, the display would have to be lying.

More importantly, the display will show zero cylinders (with the real time mpg gauge jumping to and buried at 80) in situations other than outright coasting. If you are highway cruising and let off the gas enough but not all the way, you can see zero cylinders displayed and mpg buried at 80.

I think I'll stop talking about this until somebody else actually does some testing in a model with the same display features. It's pretty easy to do.

The Mazda renderings of the valve train don't show that cylinders 2 and 3 are equipped with the hardware required to deactivate the valves, at least on the 2018 version.
 
I don't think so and I'll tell you why.

First, I'm looking at a "cylinder deactivation" display that shows no cylinders active under certain condition. So, the display would have to be lying.

More importantly, the display will show zero cylinders (with the real time mpg gauge jumping to and buried at 80) in situations other than outright coasting. If you are highway cruising and let off the gas enough but not all the way, you can see zero cylinders displayed and mpg buried at 80.

I think I'll stop talking about this until somebody else actually does some testing in a model with the same display features. It's pretty easy to do.
CD and coasting when no load and minimal fuel spray are 2 different things.

All 4 cylinders are not truly deactivated(changing the valves) when coasting.
 
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Mazda
I stand corrected @HardRightEdg

@2001birdowner and @Buzzman12 , the CD used to activate at only between 25-50mph (1st link) but Mazda may have tuned CD to be more aggressive in newer vehicles than older vehicles (2nd link) .


 
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GA prior 16 CX5 GT
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20 CX5 GT + Prem
I have set cruise at 75 mph and going down a slight hill it will switch to 2 cylinders if the grade is the ideal load for 2. I agree that when it shows all four off it is fuel cut mode for the last 2 but I do not know if the first 2 still have the valves closed...
 

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