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mpg all over the place after rebuild

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by k1ngn0thing, Mar 27, 2018.

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  1. k1ngn0thing

    k1ngn0thing Member

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    my MPG is fluctuating like crazy. prior to HV problems, I was getting 45mpg for 9 months. after replacing a bad module, it's all over the place. this started happening after it threw a code but I thought it would level out after replacing the module. prior to rebuilding, I cleared the codes to make a food run. I am not getting any codes now, but could this be because I cleared them prior to the rebuild? here's a video showing what I'm talking about. is it just relearning/recalibrating? (after parking I keep recording until the ICE shuts off):

    and here's a live OBD readout of another small trip, right around the same time (beeping is passenger seatbelt warning):

     
    #1 k1ngn0thing, Mar 27, 2018
    Last edited: Mar 27, 2018
  2. bisco

    bisco cookie crumbler

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    my mpg's have always fluctuated like that, on all 3 of my pri.
     
    #2 bisco, Mar 27, 2018
  3. k1ngn0thing

    k1ngn0thing Member

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    mine was usually around 45, except when it would jump to 99 during coasting and braking, or lower during heavy acceleration. now, it's not even always at 99 when coasting, I'm guessing because the ICE is running, and I'm not sure why it would be running more often now. I don't ever recall seeing it bouncing around at all of these random numbers.
     
    #3 k1ngn0thing, Mar 27, 2018
  4. bisco

    bisco cookie crumbler

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    how is your 12v health?
     
    #4 bisco, Mar 27, 2018
  5. k1ngn0thing

    k1ngn0thing Member

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    just put a new one in
     
    #5 k1ngn0thing, Mar 27, 2018
  6. bisco

    bisco cookie crumbler

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    what did it measure before installation?
     
    #6 bisco, Mar 27, 2018
  7. k1ngn0thing

    k1ngn0thing Member

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    don't really remember, but I've checked it since and it was over 12v, and held at 12v when in ready mode.
     
    #7 k1ngn0thing, Mar 27, 2018
  8. bisco

    bisco cookie crumbler

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    that is bad.
     
    #8 bisco, Mar 27, 2018
  9. PAUL SCHULTZ

    PAUL SCHULTZ Member

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    I've only had my Prius for a couple months but this looks normal to me. And, your block voltages and delta values look reasonable. I hate to say this but you were monitoring the instantaneous or current mpg. On the other screen you would have your average mpg. What does that screen show?

    Paul.
     
    #9 PAUL SCHULTZ, Mar 27, 2018
  10. k1ngn0thing

    k1ngn0thing Member

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    just checked and it's 12.35 at the terminals
     
    #10 k1ngn0thing, Mar 27, 2018
  11. k1ngn0thing

    k1ngn0thing Member

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    haven't driven enough yet to get a good average. will probably know in a day or two.
     
    #11 k1ngn0thing, Mar 27, 2018
  12. bisco

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    12.35 is bad, really bad for a new battery.
     
    #12 bisco, Mar 27, 2018
  13. k1ngn0thing

    k1ngn0thing Member

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    I probably haven't driven enough to charge it. guess I'll pick up a battery charger. do you think this would affect the current mpg display?
     
    #13 k1ngn0thing, Mar 27, 2018
  14. k1ngn0thing

    k1ngn0thing Member

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    I have one of these, can I charge with it?
     
    #14 k1ngn0thing, Mar 27, 2018
  15. bisco

    bisco cookie crumbler

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    some have reported that the engine runs more to charge the hybrid battery, which is trying to charge the 12v.
     
    #15 bisco, Mar 27, 2018
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  16. PAUL SCHULTZ

    PAUL SCHULTZ Member

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    I use a bluetooth ELM327 adapter and run Hybrid Assistant on my Android phone. It shows so much more and in an easier to review format than the Torque screen/PIDs. What I like is that it shows what "stage" the HSD system is in. I know on my Prius my optimum mpg occurs when in stage 4. It would have been interesting to see what stage your Prius was running in while you were taking that video.

    Paul.
     
    #16 PAUL SCHULTZ, Mar 27, 2018
  17. k1ngn0thing

    k1ngn0thing Member

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    I'll get some data with hybrid assistant on my next drive
     
    #17 k1ngn0thing, Mar 27, 2018
  18. bisco

    bisco cookie crumbler

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    i can't see it. is it for agm and 4a or less? what battery did you buy?
     
    #18 bisco, Mar 27, 2018
  19. k1ngn0thing

    k1ngn0thing Member

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    #19 k1ngn0thing, Mar 27, 2018
  20. bisco

    bisco cookie crumbler

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    i have ad blocker, might be a problem.
     
    #20 bisco, Mar 27, 2018
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