How to completely disable cylinder deactivation?

[cz5gt]

I have both. My observation is steady highway at up to 65mph the Turbo mpg is 30+ which is similar to the NA.
Above 70 ..well mazda has tuned the turbo model to be running very rich at high speeds and mpg drops to around 24-25.
City driving is low mpg but thats expected in stop and go. For city the Turbo is not the engine one wants for more highway driving its perfect

 

[N7turbo]

I have both. My observation is steady highway at up to 65mph the Turbo mpg is 30+ which is similar to the NA.
Above 70 ..well mazda has tuned the turbo model to be running very rich at high speeds and mpg drops to around 24-25.

I haven't done any data logging to look at AFRs, but at 75mph the engine is turning at 2500 rpm, which is right in the range where the turbo is making good boost. Fuel economy suffers but the passing torque is really nice.

 

[RedBaron]

Above 70 ..well mazda has tuned the turbo model to be running very rich at high speeds and mpg drops to around 24-25.

I would attribute this more to wind resistance (and friction losses) rather than running rich. The ECM will (should) always strive for perfect stoichiometric ratio for emissions reasons.

 

[sinistriel@]

The 2.5t has multiple base fueling maps that it can choose from and then apply all sorts of corrections to, like intake air temp, calculated EGT, ignition multipliers, etc.

Here is a screenshot of one of the base fuel tables. Then a screenshot from when I had my car of what AFR looks like cruising at freeway speed. It does a good job of hitting targets.

 

[tony357]

I could sometimes feel CD engage on my 2020 CX5. It didn't bother me until I had to have the transmission replaced due to the torque converter failing which was caused by CD.

have you tried a transmision relearn procedure. There are vid on Utube on doing this. Its worth a try. or just do a full factory reset of your ECU.

 

[ADS-B]

I have both. My observation is steady highway at up to 65mph the Turbo mpg is 30+ which is similar to the NA.

I cannot, for the life of me, get not even 25 mpg on the freeway. Yesterday I went to San Antonio... I think the best I had was 23, maybe 24 mpg... For me it's such a joy driving the turbo that I can't stay put doing 65 mph. No way Jose!

 

[stickerbush]

have you tried a transmision relearn procedure. There are vid on Utube on doing this. Its worth a try. or just do a full factory reset of your ECU.

Yes, dealer tried this before replacing the transmission under warranty.

 

[N7turbo]

I cannot, for the life of me, get not even 25 mpg on the freeway. Yesterday I went to San Antonio... I think the best I had was 23, maybe 24 mpg... For me it's such a joy driving the turbo that I can't stay put doing 65 mph. No way Jose!

Something is wrong. I come home from some trips like this

But most of the time I'm averaging 23.5 over the whole tank.

 

[ADS-B]

Wrong? I don’t think so. I live in Texas. People here do 85-90 mph on a 75 speed limit regularly. You can’t achieve 25 mpg fuel economy with that speed.

 

[N7turbo]

Wrong? I don’t think so. I live in Texas. People here do 85-90 mph on a 75 speed limit regularly. You can’t achieve 25 mpg fuel economy with that speed.

Very true

 

[Snake]

Wrong? I don’t think so. I live in Texas. People here do 85-90 mph on a 75 speed limit regularly. You can’t achieve 25 mpg fuel economy with that speed.

I feel sorry for you. Here in So Cal the hwy speed limit is 55-65 in the big city and 70 out in the open hwys. Of course, like everywhere else, cars zoom past well beyond the limit but since our limits are lower than yours, it's easier/safer to drive at the speed limit to conserve fuel and improve economy.

 

[ADS-B]

I feel sorry for you. Here in So Cal the hwy speed limit is 55-65 in the big city and 70 out in the open hwys. Of course, like everywhere else, cars zoom past well beyond the limit but since our limits are lower than yours, it's easier/safer to drive at the speed limit to conserve fuel and improve economy.

I appreciate it but you shouldn’t. I enjoy doing 85. It’s a turbo!

 

[Snake]

2026 Gen 3 CX-5 owner here.

Forgive me if this idea has already been covered...

I have seen here how on Gen 2s you can set the info screen to show when CD is engaging and disengaging. I haven't dug too deep into it, but I so far have not been able to bring that up to view on the new 12.9" screen of the Gen 3. I can say however, that I can detect when the engine has switched into CD mode due to the bogging and I can detect when it disengages as I push slightly harder into the gas pedal but to me it doesn't feel a whole lot different than when the trans makes a gear shift.

What I have noticed though is this. I live in the foothills. You're either going uphill or you're going downhill. There is no flatland, period. In the areas where the grade is consistent, I have learned to use the manual shifter to keep it in a gear that makes sense for going uphill in a specific speed range vs allowing the trans to upshift in an effort to increase fuel economy under light throttle. And, it feels to me that having it in manual mode will not allow the engine to go into CD mode. There is not mild jerk or bogging or any different sensation when I am manual shift mode. It simply feels like I am driving a stick shift trans. The idea is to keep the RPMs in a range that isn't pushing the engine too hard or too little or that is blatantly hurting the fuel economy. I aim for somewhere around 1700-2100 RPMS in manual mode. That requires careful observation through listening to the engine sing and it likely does hurt the fuel economy to some degree, but if it does keep the engine out of CD mode, then I think the trade off is worth it in the long run.

I enjoy driving manual transmissions in the vehicles where it is appropriate, so driving my Gen 3 like this in an appropriate situation isn't really a chore. YMMV