Sluggish Acceleration After New 12V, TF change, & TCM

2012 Toyota Prius with approximately 60k miles on it.

Needed an oil change, in the last 4 years I've owned the car got the dang 'Park in Flat surface' warning where the car would not start. Jumping it the first two times fixed it and then it happened 3 times in a week while it was getting the oil changed (also go the transmission fluid changed at this time), but the Toyota dealer couldn't get it to recreate it, so I took it home. Next time it threw that warning it ended up giving me the hybrid warning. Took it in, they said the transmission control module was bad, so they replaced it under certified warranty thank god. They also ended up putting in a new 12V battery in.

Now I've had the car for a few weeks and I swear the acceleration is so sluggish. The other day, the HV battery fan kicked on loudly, which is a rare occurrence for me (yes its 100 degrees where I live currently, but I hadn't heard the fan many times in the last 4 years). I had my foot probably 2/3-3/4 of the way down on the gas pedal and was barely going 10MPH, very very slow to accelerate. In addition the engine is very loud, especially when trying to achieve high speeds and doesn't quiet down until I let off the gas, its comparable to driving a car in third gear while going 55-60 for a noise level comparison.

I just feel like ever since they did all this work something isn't right with my Prius. I just started tracking MPG (hadn't really been concerned before that) this week so I'm still seeing how that is. I'm concerned something more is going on. All the work was done at a Toyota dealer which doesn't necessarily make me feel any better. Thoughts, comments, opinions are all welcomed! Wondering if the HV battery is going bad and dealership is ignoring it because its under warranty?

 

No it’s not an ECO mode. And I drive in POWER mode sometimes but not all the time, it turns off when the car gets shut off. It does eventually reach reasonable speeds, but actually the engine revs pretty hard between 40-70 and when you let off the gas it continues to rev for another second or two before it calms down.

 

Thanks, and that’s kind of what I figured I was driving this morning, mostly interstate with a little city and no problems what so ever. Hybrid battery was almost fully charged, no sluggish acceleration at any point, no loud engine revving. I did notice last night looking under the hood that both coolants were in the lower end, the engine coolant is below low and the hybrid coolant is right at low, could this have any effect?

I can do some work! I realize I’ve had my Prius for 4 years but I’m just realizing how much I didn’t know about it until now. (I grew up driving older Honda civics and my dad was always able to help me out with most issues.)

I’m open to suggestions, but with the issue now being intermittent I’m at a loss. I want to see how it drives this evening after sitting in the heat all day as yesterday when I drove it home from work it was very sluggish at high speeds with a noisy engine the whole way home. I was driving in POWER mode at that time, but didn’t drive in it this AM.

 

Thank you! I’ll purchase it! I’ve been wanting to see the battery function since it’s interesting and I’d like to know how’s its doing.

 

Thanks I’ll do all of this this weekend! I am a little worried they didn’t refill my tranny fluid appropriately? That’s a pain to check but it needs to be done. I do run my AC cold! I’ll check the other stuff, thank you!

 

Oh it’s been like a 100 degrees every day this week, pretty miserable. That’s good to know.

 

Did talk to a technician today and he isn’t for sure but thought it might be a gasket on the engine although he said it would be weird since I have really low miles, but he said he’s been seeing it in 3rd gens recently.

 

I took it in since I had an appointment even though the issue had resolved after the temperature dropped locally (we went from 100+ for two weeks to being in the 70s over the weekend.) They couldn't recreate the issue of course, but they topped off my coolant and I haven't had the issue since, so I feel like it might be heat related but I'm gonna watch my MPG, get the Dr Prius and I put tape on my new coolant level to watch it. Thanks everyone!