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RPMs Jump climbing up a hill

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Malacri1, Mar 6, 2018.

  1. Malacri1

    Malacri1 Junior Member

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    Hi Everyone,
    I am excited to be part of Prius Chat! however what brought me on was somewhat less exciting and a bit concerning.

    2 weeks ago I replaced my 12V battery and drove up the grape vine in California. These mountain climbs are pretty tough, and you see cars and trailers alike overheating on the side of the road. I was going 65 mph with RPMs at 4500 or so according to the scan gauge, and as I continued to climb the mountain, it felt like the car was lunging up the hills, with the scan gauge reporting RPMs jumping between 4200 and 4500 rpms. It kept doing this until the climb was over.
    • The SOC of the battery was nearly full, and did not deplete during the climb
    • The 12V battery was replaced about 2 weeks before the incident. (DIY job)
    • No Check engine light was reported
    • Oil changed at 7500k intervals
    • Transmission oil changed at 90k (DIY)
    • The car has about 101k miles
    • Chevron and Shell gas was pumped. (I did put in some STP fuel cleaner in there) on the way to Yosemite
    • Coolant temperature: 190-200 oF
    • Inverter temp: 50-55 degrees (outside it was about 37 oF)
    when SOC battery is low and the engine is charging, I do hear my engine creaking (valves?) when accelerating, but not when SOC is full and accelerating.


    Overall my MPGs have been taking a hit, under conservative driving i can barely hit 42-45 mpg highway. City is harder to test since my local driving is a 6 mile commute to work, via residential streets and that usually reports anywhere between 36-48 depending on the flow of traffic.


    Could this be a miss fire that the car isnt reporting?
    Does this indicate a dying traction battery?
    Did it not like the new battery?

    I know the Prius engine isnt directly linked to the transmission, so its harder to tell if this is a misfire, and the transmission has no clutches... so it cant be a slipping transmission.

    Thank you,
    All of your input is highly appreciated
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    My hunch is that nothing's wrong. Steep upgrades at 65 mph is going to run the rpm up, and 4200~4500 is not that much of a range. OTOH, it seems like you're describing an odd surging/hunting behavour? Not sure.
     
  3. padroo

    padroo Senior Member

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    Every misfire is not reported to OBDII, it has a certain criteria it has to meet before a code is set. A misfire is more likely at WOT because cylinder pressure is high. Could be a bad plug or coil but without data it would be hard to prove.
    I would think that if the 12 V battery was a problem it would show up in other areas, you could have it tested for peace of mind.
    It sounds like you are on top of maintenance, is the inverter full and is it moving when the car runs?

    By the way, welcome to Prius Chat
     
  4. Raytheeagle

    Raytheeagle Senior Member

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    Welcome to Prius Chat (y).

    A few questions:

    • How many miles on your Prius?
    • How long have you owned it?
    • How many miles have you put on it?
    • Have you done this exact trip before?

    I’ve done the grapevine trip in our 2010 several times with it packed full of things and 4 people :).

    While I have not experienced this phenomenon with our Prius, it might not be an issue;).

    Good luck and keep us posted (y).
     
  5. Malacri1

    Malacri1 Junior Member

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    Thank you everyone for your responses! its so assuring to have such an active forum:

    • How many miles on your Prius?
    • 100,800K
    • How long have you owned it?
    • 5 years
    • How many miles have you put on it?
    • about 60k
    • Have you done this exact trip before?
    • No, but when traveling to San Diego on the 15S bound, similar hills exist and it was doing it on those hills. I travel on those hills many times, but the only difference was a bottle of fuel cleaner, and a newish 12V battery that reports 12.4V after sitting overnight.
     
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  6. Malacri1

    Malacri1 Junior Member

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    Well I did change the 12V battery to a newer one, and usually reports 12.4V under load, and yes the traction battery had full charge. Is this what you refer to as inverter?
    Thanks!
     
  7. jerrymildred

    jerrymildred Senior Member

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    The inverter is under the hood and routes power from between the HV battery and the motor/generators and other systems. I think Padroo meant inverter coolant. When the car is on, you should be able to remove the cap on the inverter coolant tank and see the liquid swirling around a little. And it should be full, of course.
     
  8. padroo

    padroo Senior Member

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    Yes, that is what I meant, inverter coolant. I am guilty of not reading my own posts and its bad enough if I do.
     
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  9. Malacri1

    Malacri1 Junior Member

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    Hahaha well, im glad we are on the same page now. The coolant is a little low, but non the less when going up the grapevine and when the RPMs were jumping around the inverter was just 15 degrees above ambient, and ambient was 37oF. SOC was full as well. Its strange, the car only does it under load, with inclines on the freeway. Ive only noticed it with RPMs around 4000-5000.

    It feels like its lunging up the hills, its the strangest thing. NO CEL.


    Could this be related to my valves creaking when the engine is charging the traction battery, and accelerating with a low battery?
     
    #9 Malacri1, Mar 7, 2018
    Last edited: Mar 7, 2018
  10. Raytheeagle

    Raytheeagle Senior Member

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    Have you changed the transaxle fluid?
     
  11. Malacri1

    Malacri1 Junior Member

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    I changed it myself at 90k.

    Drained it from the bottom plug, closed it, filled it up through the top plug until it leaked out
     
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  12. Raytheeagle

    Raytheeagle Senior Member

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    Did you have the IPM software flash performed?
     
  13. Malacri1

    Malacri1 Junior Member

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    I did, after which i lost MPG.

    Disconnecting the battery shouldnt undo the flash right?
     
  14. Malacri1

    Malacri1 Junior Member

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    Hello,
    So its been about a year or so since I last posted this and I wanted to give an update.
    About two years ago I noticed that my Prius was having a surging problem under high load, like going up a long hill or WOT to gain speed on the freeway. At the beginning of the issue my MPG dropped to 45 mph, then 42, all the way down to 32 MPG on a bad day.
    I would get P0171 randomly, and clear them with my OBD 2 scanner; weeks or months would go by and the code will come back. There was no pattern that I could observe that would trip the code.

    The Research:
    I read a post on this forum about a member who primarily worked on the front end of the fuel delivery system. They changed MAF sensor, his spark-plugs, did the intake cleaning, PCV valve, o2 sensor. In the end of his journey, he mentioned that he had to change his fuel pump, and his P0171 codes went away.
    See article here:
    P0171 System Too Lean fixed on 2010 Prius | PriusChat

    My rational for working on the back End versus the front end:
    1.) My father has a 2014 Prius, and i tried his MAF sensor, the car was still symptomatic.
    2) I performed a vacuum leak test and there was no leak.
    3.) I had a history of adding fuel injector cleaner, and a mixture of E85 with normal petrol.
    4.) In addition, with the OB2 scanning tool, I did notice an irregularity with my Short Term and Long Term Bank Values. My short term values were always within -10-10%, which wasn't too alarming. However, my long term values were in the high +20%. Indicating that the car was running lean for an extended period of time.

    The Repair:
    got a fuel assembly unit from a Prius Scrap yard for about 100 bucks, and the hesitation is gone under WOT and uphill climbing. I was able to change the fuel assembly within an hour. The hardest part was removing the bracket to the unit. The rest was self explanatory. Remove the power to the pump and sending unit, remove the quick connect fuel line. Install new assembly, put back gasket ring.
    Another member below has posted his method for the repair.
    Changing a GenIII Fuel Filter | PriusChat

    The autopsy:
    When I removed the fuel assembly, and looked at the canister, a couple of alarming things stood out as seen in the photos below.
    Without a doubt the fuel system was CLOGGED. This can explain the surging that was felt under WOT. If the system entered an open loop cycle, the engine was demanding fuel it needed to keep up with demands, but the delivery was being restricted!

    Conclusion:
    Since pulling the battery during the repair caused the computer to reset, the current values for the long term trim are below 10%. Currently MPG is still being evaluated, and will be updated when i do an extended trip to San Diego. I hope you find this post useful, and good luck to anyone dealing with P0171 issues.

    IMG_7181.jpg IMG_7188.jpg
     

    Attached Files:

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  15. Raytheeagle

    Raytheeagle Senior Member

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    How dirty was the fuel filter?

    Thanks for following up(y).
     
  16. orenji

    orenji Senior Member

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    Sounds more like a clogged EGR Cooler. Running high RPM and the battery low will cause detonation which is what your hearing. None of this is good.
     
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  17. ChapmanF

    ChapmanF Senior Member

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    OP has already posted a follow-up that resolved the issue, and is fully consistent with the trouble code indicating lean mixture, and with long-term fuel trim values indicating lean mixture.
     
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  18. Grit

    Grit Senior Member

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    Still ain't buyin it, code schmode.
     
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  19. orenji

    orenji Senior Member

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    804D173D-8050-438E-82F8-25D5518C47A0.jpeg
    Bet ya the EGR is clogged. Look what came out of my Catch Can today.
     
  20. Malacri1

    Malacri1 Junior Member

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    It was extremely clogged, I am surprised the car even turned on, let alone gave me ~30MPG.

    I drove it to work today, about 14 miles one way and I averaged 51.8 mpg. I'm back in business with great relief.

    Long term values are reporting at 5-6%, which is more inline with an engine that has 124k miles. Cant expect perfection from a 10 year old car.
    I will be looking at the O2 sensors as preventive maintenance, but i feel it might be unnecessary.

    Thanks everyone and thanks to this community for leading me in the right direction!
     
    #20 Malacri1, Jul 8, 2019
    Last edited: Jul 8, 2019