CVT

[boqibama]

Can anybody explain why CVT Versa runs with high rpm ( almost 3k @ 40 mph) in the cold morning? Then back to the normal status (almost 1.5k @ 40 mph) once the car warms up?

[xtwoonamatchx]

every car does that... when the engine is cold, it revs higher, dont ask me why, but it does... lol so its not just CVT

[jfanaselle]

It's true that most cars do this. It revs higher so that the oil will circulate faster and the coolant will circulate faster to warm the engine up.

It's more noticable with the CVT because the transmission will alter the Gear Ratio so that the RPM's stay up, unlike a traditional automatic where it'll just idle higher and shift later until it's warm.

[BBISHOPPCM]

The other reason is because internal combustion engines lose horsepower when cold (thermal loss), shifting into a higher gear (or overdrive) when cold would overwork the engine.

[boqibama]

Thanks, guys

[Showcase]

I dont think its the engine that has to warm up, I think the transmission itself has to warm up befor it statrs reving normaly. I live in Alberta and the temp drops to -20 C overnight in the winter quite offen. My engine is warmed up, but it takes a lill longer for the transmission warm up and rev proper on my sentra.

[BBISHOPPCM]

This is true on the automatics, as ATF does thicken in cold weather. To prevent transmission damage, the automakers lock out overdrive and, in some cases, the higher gears until the fluid warms up. I suppose this is also true for CVT fluid.

[Mlody]

In the service manual one of the inputs into the "gear" that the CVT uses is temperature of the transmission fluid. Until its cold it will run at high rpm to warm up as stated before.