2010 Revving Before Engine Turns Off?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by 10Prius5, May 30, 2017.

  1. 10Prius5

    10Prius5 New Member

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    I have a 2010 Prius package 5 with ~153k. I have owned it for three years and it's had no problems until now. Forgive me if I don't know all the proper slang as I attempt to explain my issue, but any help is *tremendously* appreciated.

    In the last week or so, when the gas engine is about to cut out to switch to the hybrid battery at low speeds, just before it goes quiet from the battery switching over, the engine revs high (without corresponding foot input from me). The engine will be running fine, but then instead of just falling quiet gracefully like it normally does, it sounds like I'm revving the gas hard for about 5 seconds before the engine turns off. It's a very noticeable change.

    - Doesn't matter if it's hot or cold out
    - Doesn't matter if the car has been driven for 2 minutes or 15+
    - Doesn't seem to matter if a/c is on or not
    - Possibly related, I'm not getting that great of gas mileage for a while now according to the trip computer...on trips at highway speeds, I get up to 52 MPG or so, but once I start driving at lower speeds and around town, it drops my MPG average down to 38-42 or so. So it seems like my city driving is causing me to get crappy gas mileage (by Prius standards), but city mileage is supposed to be where the Prius shines.

    All I've done since I bought it at 125k is oil changes with inspection at the Toyota dealer...I've asked them if I'm due for any maintenance before since I'm into high miles territory and they've never told me anything, just that my car looks new...surely something ought to be wearing out or failing by now?

    Any ideas?
     
  2. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    I've noticed odd rpm spikes for the first drive or two after I've had the 12 volt battery disconnected. I speculate it's the computers relearning something? Maybe, for some reason, you're car's doing something similar.

    Check the 12 volt? Is it still the original?
     
  3. 10Prius5

    10Prius5 New Member

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    I'm pretty sure the 12v battery is due for replacement, I haven't replaced it since I've owned the car and I've had to be jumped off a few times from leaving the lights on inside. That said, I've driven it for ~2,000 miles since the last time that happened and this just started within the last week or so.

    Could an aging 12v have something to do with my symptoms?
     
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  4. DonDNH

    DonDNH Senior Member

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    Yes it could. We've had reports of very strange occurrences when the 12V is failing. It is possible that one of the ECUs is misbehaving due to low voltage and contributing to the high revs.
     
  5. bisco

    bisco cookie crumbler

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    welcome!
    also, you should try to find out what maintenance was done prior to your purchasing. there is a lot the should have been done at 120k. and you may want to consider changing the ecvt fluid.
    all the best!(y)
     
  6. 10Prius5

    10Prius5 New Member

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    Thanks for the advice...if anyone knows of other maintenance stuff I should be doing or if there's anything that commonly fails between 150k-200k, I'd be interested to know. I am considering keeping this car for a few more years, but I'm a little nervous to considering the miles getting higher...I know Priuses are designed to last a long time, but I've never had a car with this many miles.
     
  7. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    Exhaust Gas Recirculation system very regularly clogs up around those miles. Positive Crankcase Ventilation valve is good to change too.
     
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  8. bisco

    bisco cookie crumbler

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    keep a close eye on the oil, some 10's are burners. get the 12v done. if that doesn't solve the problem, you'll have to consider some other potential area's of trouble.
    if you plug the vin into the toyota owners sight, it will give you toyota dealers service history. plugs should have been done at 120k. if you can't find proof, you may want to pull one for a look see.
    150k is getting into trouble territory. if you're not comfortable, you may want to consider something a bit newer with lower miles.
     
  9. 10Prius5

    10Prius5 New Member

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    You're awesome! I had a Lexus IS350 a few years ago and knew they did the owner's site / records thing, but I didn't even think that Toyota would have one....durr >.< .....I just pulled it up and it's pretty much as I remembered from the Carfax when I bought it...previous owner was super meticulous and did everything exactly on schedule and always at the dealership, including the 90k and 120k mile factory services.

    Don't tell me 150k is trouble territory! *fingers in ears* I wanna keep this thing forever! From what I understand a perfectly maintained Prius is a pretty safe bet even into higher miles. I expect some trouble here and there but hopefully nothing costing many thousands of dollars all at once, knock on wood....
     
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  10. bisco

    bisco cookie crumbler

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    probably as safe a bet as any make.
     
  11. ChapmanF

    ChapmanF Senior Member

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    Do you have a sense of how high it revs? Do you have something like a ScanGauge, or the Torque app on a phone, to just watch the RPMs?

    Mine will sound a bit like what you've described, if it has been putting charge into the battery just before it shuts off. The power being taken from MG1 can load the engine down so it is running at low RPM but with significant throttle opening, and when the car decides to stop the engine, it generally tapers off the electrical load first, and the engine with that load taken off naturally idles up a bit while the throttle closes back down to compensate. I wouldn't describe mine as revving high, but it's noticeable. I wonder if it would be more noticeable if your throttle actuator has become a bit slower to close, or there's any unmetered air entering somewhere....

    -Chap
     
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