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How I improved my MPG - 2010 Gen 3 IV

Discussion in 'Gen 3 Prius Fuel Economy' started by SmithPriusIV, Feb 21, 2023.

  1. SmithPriusIV

    SmithPriusIV Junior Member

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    Back story, got hit a few times, front and rear collisions.

    MPG was as low as 32mpg at worst.

    1) new 12V battery. Noticeable positive change.
    2) new PCV valve. Noticeable positive change.

    If you're burning oil, you've probably got a bad PCV valve.

    3) new spark plugs and packs. Noticeable positive change.
    4) new LiFePO HV battery from Dr Prius. Gave new life to the car.
    5) new engine air filter.
    6) ethanol fuel system treatment. ICE runs much more smoothly.

    I have 183k and get 43mpg and it's still improving. I can go 40mph on just battery for, I think, about 10 miles. Not ev mode, just cruise control.

    I've also added a new water pump and did a coolant flush.

    I think the remaining mpg to recover may be found in inspecting my exhaust system. I suspect low back pressure, but not sure.

    Over all, for a gen 3 that's had a few bumps, I'm happy with how it runs and it's reliability.
     
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  2. nicoj36

    nicoj36 Active Member

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    If your car is 10+ years old and have 183k miles. Clean the maf sensor with crc maf cleaner and I guarantee you you will get at least 4-5 mpg more. Maf is oftentimes overlooked because they look clean visually but there are dusts and oils sticking on there from years and miles of use.
     
  3. douglasjre

    douglasjre Senior Member

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    EGR circuit might yield some benefit too.....
     
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Probably too late, but yeah. Toyota won’t warn you, advocate preemptive cleaning; that’d be acknowledgment they screwed up. Yeah do a cleaning, post pics of the EGR interior if possible. See top two links in my signature.
     
  5. CR94

    CR94 Senior Member

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    I've never done anything on your list except replacing the 12-volt battery 8 years ago, and have never seen less than about 55 mpg.
     
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  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Mpg depends a lot on your driving needs. Short trips, if that’s what it is, no way around it, you’re not going to see the higher end of the bell curve. But that’s ok. You still can possibly: curtail super short trips (walk), consolidate trips and so on. And don’t loose any sleep over it, ultimately you might be burning less gas.

    I’m rambling…:rolleyes:
     
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  7. Paladain55

    Paladain55 Active Member

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    i vote you disassemble your brakes and clean and lube the sliding pins. You will probably be back in the high 50s when its warm out and weather isn't a factor like me and CR.
    Also I would just unplug your egr valve electrical connector until you get your egr system cleaned. You're in the danger zone my boy
     
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    How would that help?
     
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  9. Paladain55

    Paladain55 Active Member

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    The car won't blow the head gasket
     
  10. Mendel Leisk

    Mendel Leisk Senior Member

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  11. ASRDogman

    ASRDogman Senior Member

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    After 8 years, it's probably time to replace the 12v battery....
    The inverter works harder and longer to charge the battery...
    The engine runs longer to keep the hybrid battery charged so it can
    supply power to the inverter...

     
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  12. douglasjre

    douglasjre Senior Member

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    I'd be interested in hearing from re: how the car operates when you do this
     
  13. Paladain55

    Paladain55 Active Member

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    It does great. Its been disabled on my car year round for about a year and a half now. The only slight difference is minimum throttle is a bit more throttle than with the egr running. So it is slightly not as smooth at minumum throttle above the halfway bar to keep the car from kicking the engine off on steady state crusing at 45 mph on my in town highway trips where i notice it. I'm being picky though on my observations a standard car user wouldn't notice though. So interestingly it will accelerate a bit quicker at 2000 rpm without egr. I have the egr system working though so I did run the car with both on a mixed in town city highway trip and mpg was the same, but the noticeable difference was the car would stick to 80-85% load with egr enabled and without it enabled it would stick to 70-75% load. Theoretically the more open throttle body should return higher efficiency but it my real world it didn't. Maybe if you did a lot of traveling between 45-65 it would matter more.
    But yeah I still get great gas mileage with and without EGR so i just decided to fix it up and disable in case i need it in the future. Running it just seems risky in my head for little return. I had always heard of the Brazilian and Japanese (i think) prius coming without EGR so i figured it was possible with Toyotas oem tuning.

    I've actually helped friends do it and lurkers here and there have messaged me saying they tried it with success and their engine shuddering they had instantly went away as well which was my original reason for trying it as well.
     
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  14. Paladain55

    Paladain55 Active Member

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    I actually found the gen 3 prius that came without EGR photos. Sorry to hijack thread but thought it was interesting. 1.jpg 2.jpg 3.jpg 4.jpg
     
  15. Mendel Leisk

    Mendel Leisk Senior Member

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    I'd suspect a 3rd gen Prius that came from the factory without EGR system would be tuned differently. Say different cam lobes, ignition timing, whatever. And where EGR is present, the engineers are exploiting it and counting on it to function properly.

    What's the story on that Prius, or did you explain earlier?
     
  16. Paladain55

    Paladain55 Active Member

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    Brazilian prius comes without EGR. I would be careful making those assumptions on changes without proof though. We already see the prius here that comes with EGR will run without EGR.
    I wish we could get someone to send us a brochure for that local model to read lol
     
    #16 Paladain55, Mar 13, 2023
    Last edited: Mar 13, 2023
  17. Mendel Leisk

    Mendel Leisk Senior Member

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    I like that bit.
     
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  18. douglasjre

    douglasjre Senior Member

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    I like that you like it lol
     
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  19. KamiKKazi

    KamiKKazi Member

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    If your wheel bearings are old they will affect the gas mileage. I would replace with OEM but I have had good luck with aftermarket mevotech wheel bearings.
     
  20. Che_Flo

    Che_Flo New Member

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    I followed your example when I first got the death knock back in September. As soon as I unplugged it, the rattle disappeared. Ive also had no issues since and I've probably put done around 2k miles. So thanks for the tip! I was wondering though, since you've been with it longer, if you had any thoughts on its success on a cross-country road trip? Sorry if I derailed this thread, I'm new to the chatboard