Hello, have been reading this thread with some interest. Just got a 2020 CX5 GTR to replace a 2016 CX5 GT that was totaled.
As some background, I am an automotive engineer that has worked at OEs and done calibration work on turbo engines. Not Mazdas in particular, but I know my way around engine controls and turbos in general.
The idea that Mazda arbitrarily decided that under 20F it could be slippery so power should be limited is absurd. With all of the capabilities of current traction and stability systems, traction is actively managed based on conditions, and you can certainly have more grip below 20F than above based on conditions. The same goes for picking an arbitrary temperature to limit power to prevent damage to the engine or driveline. This is all actively managed. It is more likely that certain conditions occur around 20F that are causing this issue.
When it dipped down to 15F this morning in Maryland I took the opportunity to go for a quick drive to see if I could replicate the problem and collect some data. I was a little unprepared as I did it on a whim, but I found a few things of interest. With more time there are other things I would have looked at, especially after looking at the first pass of the data.
The car was in my detached garage, so it was about 30F when I started out, despite it being about 15F outside. There is a lot of thermal mass in a car, so it takes some time for the ambient and intake air numbers to drop.
Here is the data from 4 runs that I made, in order. The approximate 0-60s are 8.0, 11.0, 10.0, 10.0 and the intake/ambient air temps were dropping (and the coolant temps were going up) as I went. All runs were reasonably flat but there was certainly some variance. Traction was not an issue.
Without getting into too long of an explanation, most modern cars use a "torque model" method of control where the throttle input is used as a "torque demand" from the driver, and the engine control comes up with the parameters to achieve that torque. The Load Value is a good measure of the torque output. That torque demand is sometimes more than what the engine is capable of, but can be less than what the engine is capable of for a number of reasons, usually to do with protecting the engine or driveline. If the limit is the driveline, it may be gear based and only apply in lower gears. On a N/A engine that involves varing things like throttle position, ignition timing, and cam timing. On a turbo engine, the boost pressure is added into the mix. Boost can be hard to control because turbos typically use boost pressure to actuate the wastegate. So you end up in a chicken-and-egg situation. If the turbo starts building boost too quickly, you "need the boost to stop the boost" and the delay in the system can make it hard to stop the boost from building quick enough.
I can't make any conclusions until I collect more data in warmer temps, but my theory based on this initial look is that when the temps get this cold the engine is capable of exceeding the torque demand at full throttle, and the control system is having a difficult time regulating it-- so it ends up taking aggressive measures to keep the torque within limits, and it is slow to recover from it.
This agrees with the thoughts other people had above about rolling into the throttle rather than stomping on in and seeing if there is a difference. Would also be interested in what would happen if you did some runs in the cold starting in manual/2nd gear.
Fortunately or unfortunately, it rarely gets under 20F here in Maryland (unlike when I lived in Detroit...)
As some background, I am an automotive engineer that has worked at OEs and done calibration work on turbo engines. Not Mazdas in particular, but I know my way around engine controls and turbos in general.
The idea that Mazda arbitrarily decided that under 20F it could be slippery so power should be limited is absurd. With all of the capabilities of current traction and stability systems, traction is actively managed based on conditions, and you can certainly have more grip below 20F than above based on conditions. The same goes for picking an arbitrary temperature to limit power to prevent damage to the engine or driveline. This is all actively managed. It is more likely that certain conditions occur around 20F that are causing this issue.
When it dipped down to 15F this morning in Maryland I took the opportunity to go for a quick drive to see if I could replicate the problem and collect some data. I was a little unprepared as I did it on a whim, but I found a few things of interest. With more time there are other things I would have looked at, especially after looking at the first pass of the data.
The car was in my detached garage, so it was about 30F when I started out, despite it being about 15F outside. There is a lot of thermal mass in a car, so it takes some time for the ambient and intake air numbers to drop.
Here is the data from 4 runs that I made, in order. The approximate 0-60s are 8.0, 11.0, 10.0, 10.0 and the intake/ambient air temps were dropping (and the coolant temps were going up) as I went. All runs were reasonably flat but there was certainly some variance. Traction was not an issue.
Without getting into too long of an explanation, most modern cars use a "torque model" method of control where the throttle input is used as a "torque demand" from the driver, and the engine control comes up with the parameters to achieve that torque. The Load Value is a good measure of the torque output. That torque demand is sometimes more than what the engine is capable of, but can be less than what the engine is capable of for a number of reasons, usually to do with protecting the engine or driveline. If the limit is the driveline, it may be gear based and only apply in lower gears. On a N/A engine that involves varing things like throttle position, ignition timing, and cam timing. On a turbo engine, the boost pressure is added into the mix. Boost can be hard to control because turbos typically use boost pressure to actuate the wastegate. So you end up in a chicken-and-egg situation. If the turbo starts building boost too quickly, you "need the boost to stop the boost" and the delay in the system can make it hard to stop the boost from building quick enough.
I can't make any conclusions until I collect more data in warmer temps, but my theory based on this initial look is that when the temps get this cold the engine is capable of exceeding the torque demand at full throttle, and the control system is having a difficult time regulating it-- so it ends up taking aggressive measures to keep the torque within limits, and it is slow to recover from it.
This agrees with the thoughts other people had above about rolling into the throttle rather than stomping on in and seeing if there is a difference. Would also be interested in what would happen if you did some runs in the cold starting in manual/2nd gear.
Fortunately or unfortunately, it rarely gets under 20F here in Maryland (unlike when I lived in Detroit...)