Transmission Question

[steve2150]

Have a 2025 Performance with the 9 speed auto. Have about 750 miles on it. Until today around town it would go into 9th gear at about 40mph but today on higheay doing 70mph it would not leave 8th gear, even tried putting it in manual mode, still stayed in 8th and refused 9th. Any ideas??

 

[5amp5on]

If you could not manually shift in to 9th at 70mph I would take it to the dealership to get checked out under warranty.

The transmission will protect you "most times" from making upshifts or downshifts even in manual mode if it would be bad for the car, but at 70 no reason you should not be able to upshift to 9th.

 

[up4speed]

Out of memory, I think I remember it doing funny things like that on mine as well. I think it's related to how you are driving before that. Maybe you accelerated to get on the highway, etc. so the transmission held the gears longer thinking that you may accelerate hard again (or maybe you were on a slight hill, and it didn't upshift, so it doesn't bog the engine). It will hold the gear, then a minute or so later, during constant speeds, it will shift up to top gear. Top gear is designed for MPG, not much else. I have also had different behavior with downshifting. Sometimes it's very gentle, then other times, if I brake hard from speed, the transmission is more aggressive, until I start driving slowly again. That's a good thing though, because you want the transmission in the right gear if you want to play. I usually drive in sport mode because it will tend to become aggressive a little easier, and I prefer that. Sometimes, even in sport mode, it still seems lazy. It's not ideal.
I'm not sure if it makes sense, but I'm trying to say that your car is most likely normal. It's just the transmission trying to predict your actions. The only confusing part is that you couldn't do it manually, but my only guess is that maybe you were going too slowly, or maybe a hill that made the engine strain too much if it shifted. Nissan is just terrible at transmission programming compared to Porsche, or even BMW. Additionally, as you get more miles on it, it will probably improve because it learns your driving style with time. (until you disconnect the battery)

 

[FSUZ33]

Not certain, but I feel like at 40 I’m in 7th. Normal highway in Standard mode it shifts to 9th around 70-75, depending on throttle. Maintaining 70 I’mpretty sure it settles in 9th. Not being able to manually shift to 9th at 70 is a red flag. Was it giving you the “you’re not going fast enough to shift“ signal, or was it not responding at all? And 9th at 40 seems off. She needs a checkup!

 

[steve2150]

Not certain, but I feel like at 40 I’m in 7th. Normal highway in Standard mode it shifts to 9th around 70-75, depending on throttle. Maintaining 70 I’mpretty sure it settles in 9th. Not being able to manually shift to 9th at 70 is a red flag. Was it giving you the “you’re not going fast enough to shift“ signal, or was it not responding at all? And 9th at 40 seems off. She needs a checkup!

Was going a steady 70 on level ground, when I moved the shifter to manual and pushed the paddle just stayed in 8th with no messages. About a 1/2 hr later when going about 55 it went into 9th.

 

[FSUZ33]

Personally, I'd get it checked out. If it is an issue, there are a lot of things that communicate for the car to shift, in auto and manual mode. It could be something simple like a faulty wheel speed sensor, or more major like the TCM or ECM. Not necessarily major, but a pain to find/fix, it could be a wiring short/open somewhere with all of the sensors/communication.

 

[up4speed]

Was going a steady 70 on level ground, when I moved the shifter to manual and pushed the paddle just stayed in 8th with no messages. About a 1/2 hr later when going about 55 it went into 9th.

That does sound strange. If it does it again, you may need to take it in to a dealer. See if you can duplicate it somehow.

 

[TitanZ]

With mine during the first couple hundred miles I noticed it would shift into 9th in the mid 50 mph range when I was breaking it in driving like a granny. But after about 500 miles it seemed to learn my driving and I had a similar experience with it staying in 8th. I would have to switch into manual mode and use the paddle shifters to up shift into ninth, but now I figured it out. I now have over 11K miles in less than 6 month, mostly highway miles so I can confirm that 72 mph is the exact trigger speed for when the tranny will upshift on its own into 9th. I’ve been able to hit 37mpg cruising.

 

[FSUZ33]

Z just broke 5K miles this morning
In both Standard and Sport, flat ground, light throttle (basically maintaining speed) I get upshifts from 8th at 72 and downshifts from 9th at 64.

 

[alienpoker]

I agree- at 70 it stays in 8th. At 72-73 it always shifts to 9th. I think I’ve been able to paddle shift to force 9th when accelerating slightly below 72 maybe at 69-70…
Hitting 9th gear at 40 sounds wrong to me when cruising around town. It must be in a “break-in period” & still learning your driving habits.

 

[FSUZ33]

When it shifts into 9th at 72 it drops to what, 1500 rpm?…less? If we say 1500 rpm, that puts 40 mph in 9th at 850 rpm. That’s idle speed, or lower, depending on conditions. At low rpm in a high gear, it seems like if you stomped on it, it would put A LOT of stress on components that aren’t meant to handle that. Like riding a bicycle up a hill in high gear. If you’ve got the mass of Lizzo and the thighs of The Rock, you’ll break the cassette or something trying to keep it moving. Maybe the car’s smart enough to not let that happen. Maybe I’m full of crap. Idk. Regardless, I’d take it in.

 

[RobotAZ]

When it shifts into 9th at 72 it drops to what, 1500 rpm?…less? If we say 1500 rpm, that puts 40 mph in 9th at 850 rpm. That’s idle speed, or lower, depending on conditions. At low rpm in a high gear, it seems like if you stomped on it, it would put A LOT of stress on components that aren’t meant to handle that. Like riding a bicycle up a hill in high gear. If you’ve got the mass of Lizzo and the thighs of The Rock, you’ll break the cassette or something trying to keep it moving. Maybe the car’s smart enough to not let that happen. Maybe I’m full of crap. Idk. Regardless, I’d take it in.

With 9 gears it’s eager to downshift, which is furthered by enough turbo and drive by wire lag that I cannot imagine it being an issue.

 

[TitanZ]

Just when I thought I had the shifts into ninth figured out at only happening at exactly 72 mph, yesterday it shifted into ninth at 47 mph on two occasions when I had to drive really slow on some really narrow backcountry roads, I think my RPMs were around 1100.

 

[up4speed]

Just when I thought I had the shifts into ninth figured out at only happening at exactly 72 mph, yesterday it shifted into ninth at 47 mph on two occasions when I had to drive really slow on some really narrow backcountry roads, I think my RPMs were around 1100.

It's not only RPM dependent but also load dependent. It's all in the programming. This car is a little weak in that area in my opinion, but not horrible. Definitely responds better when driven hard in Sport+ mode.

 

[RobotAZ]

It's not only RPM dependent but also load dependent. It's all in the programming. This car is a little weak in that area in my opinion, but not horrible. Definitely responds better when driven hard in Sport+ mode.

I agree it is RPM and load dependent, but there is also something related to throttle inputs (aka driving style) that I haven’t figured out. It will hit 9th in the 40’s and 5 minutes later it won’t, in identical conditions (ie flat road, speeds, even attempted throttle inputs).

I mostly drive with boost at 0 psi or less. It’s possible hitting boost above 0 psi adds input to the computer. I haven’t paid attention, but will start.