Abnormal up shifting and down shifting.

The Prius doesn't down shift or upshift... The Hybrid Synergy Drive is a planetary gear system with some electric motors that both provide rotational force as well as the ability to generate electricity from existing rotational force.

The closest thing a Prius has to the feel of down shifting or upshifting would be if the battery is drained down or too cold to use more than lightly, causing the gas engine to work harder (higher RPM), which would feel like down shifting. Or when the battery is fully charged and engine power isn't needed as much (lower RPM) which would feel like upshifting.

If there's something wrong with this system an app like Dr. Prius app via a $20 OBD2 reader would give you the data for that.

 

There are NO gears in the CVT. So there is not shifting.
And there is NO flush either. Just drain and refill. But the car must be level so you'll have to
raise the front and rear of the car. And remove the FILLER plug first!!!!

You need to get a good code reader and see if there are any codes.
You could likely have issues with the plugs, or bad fuel.
It sound like you are not getting full power from the engine.

Check your air filter, engine air filter. It could be clogged, or dry rotted.
There are also sensors to clean...

 

Deep cycling NiMH can restore a battery at 50% capacity back up to 96%. Usually needs to be done every 18 months on older packs. It takes lots of patience.

Hybrid Automotive and Maxx Volts sell products to do this. Or you can build your own: Build Hybrid Battery Maintenance Gear For Under $100 | PriusChat

 

It won't go into ev mode over 26mph.
If you suspect the hv battery, you should do a test.
The Dr. Prius app can do that. Or if you have techstream or the D8, those can test it.

You shouldn't randomly discharge/charge the battery. You can't really do that with out the
proper equipment. You can get the Prolong system to do that.
The computers will only keep it between 20-80% state of charge. So unless you turn the car off
when the engine starts, or leave it in neutral, the battery won't get very low.

You should also check the other things I mentioned. Put some fuel injector cleaner in the fuel also.
Since you don't have much mileage, there are several things it could be.

You may have to find a GOOD Prius shop that will go over the car and find the real cause of your issue.

 

Sure, gears don't slide around and mesh and unmesh, but c'mon.

A transmission is a thing that lets the ratio of engine rpm:wheel rpm change. In my last stick-shift passenger car, those ratios worked out to:

• 1st gear: 14.02 (you'd hit 2500 engine rpm at 12 mph. 5300 at 25 mph)
• 2nd gear: 7.561 (2500 at 22 mph, 5300 at 47 mph)
• 3rd gear: 5.295 (2500 at 32 mph, 5300 at 67 mph)
• 4th gear: 3.768 (2500 at 45 mph, 5300 at 95 mph)
• 5th gear: 3.001 (2500 at 56 mph, 5300 at 119 mph)

An engine at 2500 rpm sounds like it's doing good honest work, and at 5300 (top rpm a gen 3 Prius ever uses) it's got a nice howl to it.

In any transmission, whenever the transmission changes <whatever> so the engine revs higher at the same road speed, that's a downshift. When it changes <whatever> so the engine revs lower at the same road speed, that's an upshift.

The Prius transmission can cover that whole range of ratios in a continuously-variable way instead of with 5 fixed steps. But the range of ratios it gives between the engine and the wheels is pretty much the same range, and what you hear when the engine sound goes higher for the same road speed (downshift effect) or lower for the same road speed (upshift effect) is pretty much what you hear in other cars, except it doesn't go in fixed steps.

For example, when I was testing my gen 3's engine braking on a hill in Indiana, it hit 3936 engine RPM down the hill at around 36 mph, and the sound and the feel were about the same as my older stick-shift car would have sounded and felt if I downshifted to 2nd on that hill at that speed, which is about what I would have done in that car.

The nifty details of how our transmission does that inside doesn't mean we have to stop people from saying 'upshift' or 'downshift' when they know what those sound like in other cars and their ears are hearing the same thing.

 

Lol, yet again you're disagreeing with me without actually saying anything that's in disagreement with what I said. Please stop trying so hard to be argumentative!

 

See post #8

 

I wouldn't connect it in any way with the symptoms described here. The oil in a Prius transmission is only there to lubricate things and carry away some heat. In some other automatic transmissions it plays a role in controlling the works, but not in a Prius.

 

When I first got my prius, it was doing the same thing you describe here.

I quickly thought to change out the ATF.
After having that done, the issue was resolved.

Sometimes it is experience with the exact issue, that will help you get to the answer.

 

Certainly.

An opportune time to replace the transaxle fluid is around 10k miles or a year. I've done maybe 3, and with the first, around that interval, the fluid was darker than any of the subsequent drains. The last one I resolved to leave it alone for a good long time. My conclusion: the main benefit is to drain the manufacturing debris, and from then on it's much more stable.

More info in my signature. On a phone turn it landscape to see signatures.

 

08886-81210 Toyota ATF WS

 

There’s a transaxle fluid change link in my signature. (On a phone turn it landscape to see signatures).

Toyota refers to the Prius gearbox as “transaxle”.

Your owners manual stipulates Genuine Toyota ATF WS fluid, and cautions that use of anything else may damage the transaxle.

 

Not just Toyota, that's the industry-wide term for any gearbox that combines the transmission and the final axle drive. Typical on a front-wheel-drive car.

 

Yeah I do notice various spell-checkers auto-complete "transaxle".