Hello,

I have a 2015 CX5 Maxx Sport AWD Auto that has around 63,000 kms on it. Recently I have noticed that when I drive down hill my RPM's will increase to over 3000.

I drive normally around 50 / 60kmh, I start to drive down the hill, I brake lightly to slow down with the traffic and the RPM's will increase to over 3000 from around 1700, and sounds like the engine is being revved. It will only go back to the normal rev range if I change up manually to a 5th or we get back to the flat. The reason I ask is that I have never noticed this until the last few months. We have had the car for 5 years from new. Mazda service said all okay with the gearbox and clutch.

Thanks for reading.

 

That doesn't sound right but can't say for sure as we've only had our CX-5 for a few weeks. However it's not typical of most automatic transmissions I've experienced. It sounds like the vehicle is in Sport mode, though I don't know if he 2015 models offered this.

The only thing I can offer is that the ECU on modern cars "learn" our driving techniques and adapt over time. Any new drivers in the family? You could try resetting the ECU by disconnecting the battery (maybe try the procedure described here: https://www.mazdaforum.com/forum/gen...setting-31827/)

 

When using the cruise control on my 2016.5, I notice the transmission will downshift when going downhill. It will also downshift if I am braking while going down a hill. I assume it is programmed that way to use engine braking to help hold speed when going downhill.

 

[QUOTE=moparmarc;186836]That doesn't sound right but can't say for sure as we've only had our CX-5 for a few weeks. However it's not typical of most automatic transmissions I've experienced. It sounds like the vehicle is in Sport mode, though I don't know if he 2015 models offered this.

Thank you for the reply. On the last service they mentioned ECU, and I am sure they said that they reset it because it may have learnt the driving style. No new drivers, just me and the wife. I will have a look at the link and try it. It's odd that it up shifts rather than down shift, which I would expect to help with downhill braking. I have only noticed it over the past few months, and you really notice it when it happens.

I rarely use Sport mode, but did check it wasn't on the first time it happenned.

Hoping this isn't the start of something nasty. thanks again.

 

I think you are overthinking it; a number of manufacturers have used a quick downshift to aid in braking for years now. If I recall correctly Honda started the trend back in the 1990s.