Wow, I'm really glad I found this thread! I've recently noticed this issue when temps fall below around -5c here in Ontario, Canada. At first I thought it might be a traction control issue but quickly ruled that out. After a bit more testing I started noticing that power returned after 3rd gear; the issue seemed mostly limited to 1st and 2nd. The acceleration difference is
drastically different and has caught me out a few times when needing to quickly pull out into busy traffic. In my opinion, this is actually a little bit dangerous, as the difference in acceleration isn't minor. You become used to how a car drives and when it unexpectedly doesn't perform or behave how it should, it can be a little frustrating. Canada is cold in the winter. I typically run 94oct, so I expect at or near 250hp, even in the cold.
I have owned two Subaru WRX STis, both tuned by me, and currently driving my wife's old '09 WRX (waiting for the next STI). None of those cars exhibited this issue in the winter, stock or modded. I understand the argument that the ECU tune on the CX-5 turbo is likely attempting to prevent over-boost or protect the engine in some way. The turbo Subarus have a similar feature in the ECU maps called Wastegate Duty Cycle Intake Air Temperature Compensation (or something like iirc). So as the air temp drops, the duty cycle is lowered, allowing more bleed off of exhaust energy. This helps prevent over-boosting when the air is more dense. Now, with that said, even though the boost target and WGDC are lower, the Subarus still drive as expected. My wife's '09 WRX pulls just as hard in 1st and 2nd whether it is summer or winter. The CX-5, not so much.
Mazda should really sort this out or release a technical service bulletin about it. I don't know if it is due to DPT and/or DI, but given the
drastic difference in power
and the fact that there is no official notice or warning anywhere about this could get Mazda into some hot water if someone were to press the issue. We're not talking a 10-15hp drop - I swear when this issue occurs, the car isn't making much more than 160-170hp, until 3rd kicks in and then it's mostly back to normal.
Thankfully, it's my wife's car and mainly meant to be a fun commuter and travel vehicle. I still love almost everything about it, the fit & finish, the driving feel, and the acceleration ... when it isn't being limited.
I'm glad this thread exists though, as I truly thought I was going nuts or that there was something wrong with the vehicle.
Edit:
The really odd thing about this issue is how abrupt the changeover point is. It certainly doesn't feel like the ECU progressively pulls boost (and timing) as the temps lower. The boost-cut seems to occur at a very well-defined air temperature - almost like an all or nothing situation. Now maybe the tables for target boost and IAT compensation don't have a lot of resolution, so the steps between air temp ranges are relatively abrupt...who knows. But it sucks whatever the reason.