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

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Rachel Lynn, Jul 18, 2019.

  1. Rachel Lynn

    Rachel Lynn New Member

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    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?
     
    #1 Rachel Lynn, Jul 18, 2019
    Last edited: Jul 18, 2019
  2. CR94

    CR94 Senior Member

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    Is it in ECO mode? Did you have it in POWER mode before the work was done?
    Mine has consistently featured sluggish acceleration, but getting over 10 mph is not too difficult.
    Does it eventually reach reasonable speed?
    High battery temperature can limit its contribution.
     
  3. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    I don't think the dealership would avoid warranty hybrid battery replacement; they still get paid, albeit at a more down-to-earth rate? And yeah it does sound like it could be the battery.
     
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  4. schmuber

    schmuber Member

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    Had somewhat similar gremlins last year, also started guessfixing it with the new aux battery… in the end had to replace an integration relay. Not cheap ($250-ish for the part), but it cured the issue.
     
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  5. Rachel Lynn

    Rachel Lynn New Member

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    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.
     
  6. bisco

    bisco cookie crumbler

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    welcome!
    if you're not getting any dash lights, the battery isn't going bad to the point that they will do anything about it.

    i can make a lot of suggestions, but if you aren't going to do the work yourself, you will likely spend a lot of money until you find the culprit.
     
  7. Rachel Lynn

    Rachel Lynn New Member

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    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.
     
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  8. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    Try Dr Prius with a blue tooth adapter, for some insight on the battery? The app is free download and and the adapter's about $20.

    I've just started playing with that (using Carista; there's a static test you can do (all I've done so far), that shows the at-rest block voltage and resistance. There's also a couple of tests that require you to:

    1. accelerate/decelerate hard.
    2. have the car idling within a certain load range

    Those two tests will give more assessment, estimate battery health/life.
     
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  9. Rachel Lynn

    Rachel Lynn New Member

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    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.
     
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  10. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    Maybe put a piece of masking tape on the engine coolant reservoir, mark the level with a black felt marker pen, then monitor.

    There's a good chance it's just gradual drop: I know with ours after about 4~5 years both levels were near the low marks. I purchased a gallon (that's the only size they sell) of the spec'd coolant (Toyota Super Long Life), topped both reservoirs up to full mark, and they haven't budge since.

    On the other hand, if you see a drop in engine coolant level, say within a week or two, that could indicate engine head gasket problems. Still, I suspect not: if that was the case you'd be needing to regularly top it up, would have that gallon of coolant by now, lol.
     
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  11. bisco

    bisco cookie crumbler

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    get a volt meter and test the 12v health. make sure the connections are clean and secure, especially neg to ground.
    make sure the battery cooling fan intake grille is clear and clean, and clean the cooling fan. do you carry any pets?
    check the oil level once a week and the tires pressure.

    check/clean/replace the engine air and cabin filters.

    plug your vin into the toyota owners website and look for open recalls and maintenance records.

    a bit more difficult, make sure they topped up the tranny fluid. if you can get someone to put it on a lift, much easier.
    is the a/c cold enough? always run it high when it is hot outside, it helps the hybrid battery as well as you
     
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  12. Rachel Lynn

    Rachel Lynn New Member

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    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!
     
  13. bisco

    bisco cookie crumbler

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    i'm not saying it's likely, or the source of your problem, but i think it is worth checking. i just don't trust dealerships to do things properly.
    no rush, but worthwhile when you can, i think.
     
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  14. ChapmanF

    ChapmanF Senior Member

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    A Prius will protect its battery if temperatures are extreme, meaning less contribution from the battery, and more work from the engine. Temperatures are pretty extreme here. I don't know what you're seeing in Nebraska.
     
  15. Rachel Lynn

    Rachel Lynn New Member

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

    Rachel Lynn New Member

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    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.
     
  17. bisco

    bisco cookie crumbler

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    oh boy, i hope not. there is a gen3 head gasket problem, but 60k is a little early. usually around 100k.

    now i'm going to have to clean my egr :unsure:
     
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  18. Grit

    Grit Senior Member

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    It sounds like the HV battery is in protection mode due to heat, which shuts off the electric side, and with only gasoline propelling the vehicle. This had happened to me before because of hot inside temp from summer heat. The 3rd gearish type of drive in hot temp is my best guess.
     
  19. Raytheeagle

    Raytheeagle Senior Member

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    Might want to get to know @Bay Stater or @m.wynn a bit better:).

    They’d have your back(y).
     
    #19 Raytheeagle, Jul 19, 2019
    Last edited: Jul 20, 2019
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  20. Rachel Lynn

    Rachel Lynn New Member

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    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!
     
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