1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Mysterious misfire ONLY when low HV battery, but No DTC’s

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Baz2473, Jan 23, 2019.

Tags:
Page 1 of 3
  1. Baz2473

    Baz2473 Junior Member

    Joined:
    Feb 8, 2015
    37
    16
    0
    Location:
    Kent. England.
    Vehicle:
    2010 Prius
    Model:
    N/A
    Hey all. Has anyone else encountered the random, mysterious misfire that only sometimes happens and only ever when the HV battery is low and never throws a single fault code?

    Here’s a little background info on the car.
    2015 last of the gen 3’s
    196,000 miles.
    No loss of oil or water.
    Never ran low on oil.
    Regular services.

    At 195,000 it developed the famous engine knock on startup along with this new mysterious misfire (or at least it feels like a misfire)!

    Stripped out the entire egr system. (Cooler, valve, Pipe & intake manifold) cleaned throughly, replaced the PCV valve, introduced an oil catch can, removed and ultrasonic cleaned the fuel injectors. Replaced all 4 spark plugs. All had no effect on the misfire but did cure the startup knock...

    Anyone have any ideas or experience with this? Any help would be appreciated.
     
    #1 Baz2473, Jan 23, 2019
  2. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,527
    8,429
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    Many have reported the low SOC misfire. Has the car overheated before? Failed water pump/inverter pump?
     
    #2 JC91006, Jan 23, 2019
    Mendel Leisk likes this.
  3. Baz2473

    Baz2473 Junior Member

    Joined:
    Feb 8, 2015
    37
    16
    0
    Location:
    Kent. England.
    Vehicle:
    2010 Prius
    Model:
    N/A
    Never overheated and no apparent problems with either pump.
     
    #3 Baz2473, Jan 23, 2019
  4. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    110,184
    50,069
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    plugs, injectors, throttle, maf?
     
    #4 bisco, Jan 23, 2019
  5. Baz2473

    Baz2473 Junior Member

    Joined:
    Feb 8, 2015
    37
    16
    0
    Location:
    Kent. England.
    Vehicle:
    2010 Prius
    Model:
    N/A
    New plugs. Ultrasonic cleaned injectors, maf untouched.?
     
    #5 Baz2473, Jan 23, 2019
  6. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,527
    8,429
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    So basically you can drive the car trouble free as long as the battery SOC does not go to 2 bars? When I read about this problem 2 years ago, I couldn't figure out how the low SOC would do that to the engine. 2 years later.....I'm still unsure...............

    I did buy a car with the low SOC misfire problem, but that car also had a bad head gasket, that was repaired using some coolant additive. Long story, that car was sold before I even registered it to my name.
     
    #6 JC91006, Jan 23, 2019
  7. Baz2473

    Baz2473 Junior Member

    Joined:
    Feb 8, 2015
    37
    16
    0
    Location:
    Kent. England.
    Vehicle:
    2010 Prius
    Model:
    N/A
    That’s correct. It runs like a dream unless that battery is under the half way mark. The lower it is the worse the misfire?
     
    #7 Baz2473, Jan 23, 2019
  8. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,527
    8,429
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    So the remedy is to not let the car SOC get low. I would recondition the battery now and get it as strong as possible. Then whenever you're at a stoplight and you see the SOC drop low, do a force charge on the car and get the SOC back up (only take 30 seconds or less)
     
    #8 JC91006, Jan 23, 2019
  9. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,527
    8,429
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    I know you cleaned out the EGR valve, I wonder would replacing it help? It's not hard to get to (much easier than the damn cooler)
     
    #9 JC91006, Jan 23, 2019
  10. Baz2473

    Baz2473 Junior Member

    Joined:
    Feb 8, 2015
    37
    16
    0
    Location:
    Kent. England.
    Vehicle:
    2010 Prius
    Model:
    N/A
    That is what I currently do, I was just hoping that there was a permanent fix rather than messing around like that can’t afford a new hybrid battery...
     
    #10 Baz2473, Jan 23, 2019
  11. Baz2473

    Baz2473 Junior Member

    Joined:
    Feb 8, 2015
    37
    16
    0
    Location:
    Kent. England.
    Vehicle:
    2010 Prius
    Model:
    N/A
    Was thinking this myself but wasn’t sure if that could be the reason for the misfire? Do you know if unplugging it would be a way of testing if this would cure it. (If I unplugged it when the valve was closed) ?
     
    #11 Baz2473, Jan 23, 2019
  12. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,527
    8,429
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    I'm going to have to defer to some of the guys that knows this stuff better, I don't really know the answer......in 24 hours, you'll get get some more responses.
     
    #12 JC91006, Jan 23, 2019
  13. tankyuong

    tankyuong Senior Member

    Joined:
    Nov 9, 2012
    1,555
    661
    0
    Location:
    Central MO
    Vehicle:
    2012 Prius c
    Model:
    II
    Mine did the same and finally blew a hole in the engine 2 months later
     
    #13 tankyuong, Jan 23, 2019
    bisco likes this.
  14. Mendel Leisk

    Mendel Leisk EGR Fanatic

    Joined:
    Oct 17, 2010
    56,708
    39,244
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Where was the hole; did you figure out what failed?
     
    #14 Mendel Leisk, Jan 23, 2019
  15. tankyuong

    tankyuong Senior Member

    Joined:
    Nov 9, 2012
    1,555
    661
    0
    Location:
    Central MO
    Vehicle:
    2012 Prius c
    Model:
    II
    The hole was in the block, replaced the engine
     
    #15 tankyuong, Jan 23, 2019
    Mendel Leisk likes this.
  16. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    110,184
    50,069
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    rings?
     
    #16 bisco, Jan 23, 2019
  17. Baz2473

    Baz2473 Junior Member

    Joined:
    Feb 8, 2015
    37
    16
    0
    Location:
    Kent. England.
    Vehicle:
    2010 Prius
    Model:
    N/A
    Thank you for your help.
     
    #17 Baz2473, Jan 23, 2019
  18. Raytheeagle

    Raytheeagle Senior Member

    Joined:
    Jul 1, 2016
    11,257
    15,491
    0
    Location:
    Bay Area, California
    Vehicle:
    2019 Prius Prime
    Model:
    Prime Plus
    What are you using to read codes?

    Have you tried moving the coils around and see what happens?

    Still got the old plugs for comparison?

    No lights on the dash?
     
    #18 Raytheeagle, Jan 23, 2019
  19. Baz2473

    Baz2473 Junior Member

    Joined:
    Feb 8, 2015
    37
    16
    0
    Location:
    Kent. England.
    Vehicle:
    2010 Prius
    Model:
    N/A
    Techstream to read codes. (There is none)
    Swapping coils around made no difference.
    Yes still have old plugs. (See attached pic)
    No warning lights what so ever.
     

    Attached Files:

    #19 Baz2473, Jan 24, 2019
  20. Baz2473

    Baz2473 Junior Member

    Joined:
    Feb 8, 2015
    37
    16
    0
    Location:
    Kent. England.
    Vehicle:
    2010 Prius
    Model:
    N/A
    Ok. So I’ve decided to take off the entire EGR system again including cooler and IM and give it a through ultrasonic clean. Hopefully this will help. ?
     
    #20 Baz2473, Jan 26, 2019
(You must log in or sign up to post here.)
Page 1 of 3