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Funny (not really) downshifting for 2008 Frontier

I have noticed some other posters here hinting at this problem with no answer yet.

When down shifting from 5th to 4th gear (Automatic Transmission), i feel my truck downshift, but the engine still revs up 1500 RPM or so (with no increase to the speed). Tried to recreate the situation with a Nissan tech with me driving it for about 15 minutes; no dice.

When i hit the overdrive button, problem solved, but i dont want to be driving with overdrive off all the time.

thanks,

george.

I am not sure I understand what the problem is.

If you shift from 5th to 4th, then you should expect an increase in engine RPM. That’s how it works.

sorry, this is after i let off the gas.
its like the engine surges after i let off the gas when the engine should just be “coasting”. Then when i get back on the gas, the engine’s rpm stays a little too high, and then comes back down. I’ve heard it could be a throttle sensor, but i dont know if that’s the case of not. This is my 5th Nissan, so i know something isnt right.

“When down shifting from 5th to 4th gear (Automatic Transmission), i feel my truck downshift, but the engine still revs up 1500 RPM or so (with no increase to the speed).”

Still very confusing. Are you doing the down shifting here (from 5th to 4th) - or are you assuming that the transmission is? You did say it is an automatic, but you’re talking about it like a manual. You also first said it was “when downshifting” and then said it was after you let off the gas.

When you say rev up 1500rpm - do you mean that it stays at around 1500 rpm or that it goes up by an additional 1500rpm without you being on the accelerator?

Here are just a couple of things - if you are up at cruising speed with constant acceleration and you let off the gas the auto trans won’t downshift. It will downshift only if you get on the accelerator and “ask” it to. If you do let off of the gas suddenly, one thing that might happen is that the torque converter clutch (TCC) will unlock. When it unlocks, the rpms will jump a little - perhaps by 2-300. When you get back on the accelerator and get to steady speed the TCC will kick back in and the rpms will drop back down that few hundred. Hitting the O/D off button will turn off the TCC lockup so that it never locks up. Thus, you wouldn’t get that little rpm jump.

So your description is confusing but I think that you’re watching normal TCC operation. However, if you’re talking about an RPM jump of 1500 (rather and 2-300) then something else is going on.

Its an automatic.
I’m not shifting anything; i can just feel the transmission automatically doing what it needs to do when i let off the gas.
I dont think its normal TCC operation. This jump occurs about 35 percent of the time. I know its not normal operation because whenever i have a passenger and the jump occurs, they are like "what the heck is wrong with your truck?"
Thanks for your help; trying to get this figured out while its still under warranty.

Ho large an RPM jump are you seeing?

the RPM goes up about 1000 to 1500 without being on the accelerator. When i get back on the accelerator, the surging continues and then goes back to “normal” after about 2 or 3 seconds. Again, this whole problem only occurs some of the time, but i’m just trying to figure out if its the root of a bigger problem.
its been scanned for codes at 2 different places, and none were found.

Is it under warranty and that is why you are dealing with a Nissan tech? You need the transmission specialist and it needs to be put on a scanner to find out if any codes are stored and exactly what the thing is doing and when.

sounds like it downshifts while it is coasting, but when you step on it, it shifts back up to OD

I have just bought a 2019 Frontier it is an SV 4x4. What I experience is that, (*Sometimes) when approaching 35mph instead of shifting up into overdrive it will shift down into fourth. After a few seconds if I don’t get on the gas, it will shift back up. This takes it from about 1000 to 1500 then back to 1000.