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

Slightly "Rough" Idle at standstill w. Low Traction Battery

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Canard, Oct 3, 2024 at 8:44 AM.

  1. Canard

    Canard Member

    Joined:
    Sep 2, 2010
    214
    39
    5
    Location:
    Ontario, Canada
    Vehicle:
    2010 Prius
    Model:
    N/A
    I have a bit of an odd one...

    2010, 415k km (257k miles)

    Here's the scenario:

    -Stopped in traffic (vehicle stationary)
    -Engine is hot/warmed up (have been driving for a while)
    -Traction Battery eventually drops down to two bars (low)
    -Engine comes on to charge up traction battery
    -Engine sounds like it is revving at a slightly different rpm than normal idle (maybe a little slower?)
    -Engine sounds a little "rough"

    Once the battery gets up to 3 bars again, the engine shuts off... and if I drive off at any point and the engine kicks on, everything sounds fine/smooth.

    I'm wondering what is causing this slightly rougher idle in this exact specific scenario.
     
    #1 Canard, Oct 3, 2024 at 8:44 AM
    Last edited: Oct 3, 2024 at 9:08 AM
  2. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    56,241
    39,021
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    I’ve experienced the same, would suspect it’s normal.
     
    #2 Mendel Leisk, Oct 3, 2024 at 9:05 AM
    Canard likes this.
  3. Brian1954

    Brian1954 Active Member

    Joined:
    Jan 31, 2021
    998
    358
    0
    Location:
    South Central PA, USA
    Vehicle:
    2011 Prius
    Model:
    III
    This also happened to me a year or two ago when I had the AC turned on. It is not usual for me to be stopped in traffic for long periods of time. It has not happened again, so I am not concerned.
     
    #3 Brian1954, Oct 3, 2024 at 9:38 AM
    Canard likes this.
  4. Canard

    Canard Member

    Joined:
    Sep 2, 2010
    214
    39
    5
    Location:
    Ontario, Canada
    Vehicle:
    2010 Prius
    Model:
    N/A
    I took a look again this morning, and noticed the grey "Hybrid Synergy Drive" cover was rattling around pretty good at this lower-rpm idle, so I'm wondering if it's just a resonance thing that specific engine speed. It went away entirely (cover didn't rattle) when the engine bumped up in rpm slightly after the battery was 3+ bars...
     
    #4 Canard, Oct 3, 2024 at 9:42 AM
  5. BiomedO1

    BiomedO1 Senior Member

    Joined:
    Mar 27, 2021
    1,680
    868
    0
    Location:
    SacTown, Ca
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    Check and clean out your throttle body and air intake pathway. A sticky throttle body flap would cause this. As for the engine 'beauty" cover; I always remove them and store it with my maintenance parts box. I prefer to see problems that may be masked by that cover and takes away the roof of a mouse house.:cool::whistle:

    On my old Prius C, the idle should be slightly faster than normal, when it's recharging a low traction battery. When was the last time the engine was tuned up? You may also have a weak cylinder that can be verified by looking at the spark plug and/or bore scope. That's a pretty objective test. A quantifiable test is compression and leak-down test.

    Hope this helps.....
     
    #5 BiomedO1, Oct 3, 2024 at 12:42 PM
    Canard likes this.
(You must log in or sign up to post here.)