MPG 4MPG lower after Software upgrade/Recall

Discussion in 'Gen 3 Prius Main Forum' started by jl2013Prius, Jan 14, 2019.

  1. jl2013Prius

    jl2013Prius New Member

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    Last week I had my 2013 Prius III at the dealer for the 70Kmile service. Besides the normal items, I had the transmission fluid changed. And then the Hybrid System Software Update for NHTSA Recall 18V-684 was applied.

    I filled the tank last Friday and reset the trip/mpg counter. Normally in the winter I get a reading of 46-47MPG from the trip display; in the summer I get 50-52. After 90 miles, it's showing a reading of 42.3MPG. I checked the tire pressure, the two front tires were at 28, I inflated them back to 35. I added a couple lbs to the rear tires. I doubt that is the answer to the total difference. I suppose it could be bad gas, but I doubt it; its from an Exxon station I use regularly.

    The other thing that is noticeable from the display is that it doesn't go into EV mode as quickly as before, based on the display with the power chart that goes back and forth. What I am used to is within a second of taking my foot off the gas, the EV indicator comes on. Now I have to coast 5+ seconds before it comes on. If I switch to the display that shows the Engine and Battery and the direction of electric flow, it does show the engine shutting down within a second or two of releasing the pedal.

    Anybody else have this recall performed and noticed the same thing?
    If not, what else may it be?

    Thanks
     
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  2. bisco

    bisco cookie crumbler

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    welcome!

    yes, quite a few. unfortunately, there doesn't seem to be a fix. you might request a do over, in case they botched it, but i don't recall that fixing it for anyone.
     
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  3. Grit

    Grit Senior Member

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    The software update you mentioned Is to fix the non limp mode. Sounds like an accumulative upgrade which consist of previous software upgrades was part of it also; the one that reduces inverter uptime and more gas time.

    There’s a PC member here that has recall documents piled up &yet to be completed, I have the same pile also.
     
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  4. bisco

    bisco cookie crumbler

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    <raised hand emoji>
     
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  5. Johnny Cakes

    Johnny Cakes Active Member

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    So do you suggest telling the dealer NOT to do the upgrade, if the car is there for some other work?

    I wonder whether they can follow that instruction or are required to do the upgrade -- i.e. would refuse to work on the car if permission for the upgrade is declined.
     
  6. audiodave

    audiodave Active Member

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    I'm sure everything is reset like when battery is disconnected so may take a tank to improve.

    Posted via the PriusChat mobile app.
     
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  7. Bay Stater

    Bay Stater Senior Member

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    Prius engine management system has to relearn?? As @audiodave has already mentioned, give it a few tanks. Keep us posted.;)
     
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  8. audiodave

    audiodave Active Member

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    Once battery is disconnected there is some adjusting the computer needs to do. That's on all computer controlled cars.

    Posted via the PriusChat mobile app.
     
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  9. bisco

    bisco cookie crumbler

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    i refused the gas pedal haircut and floor mat zip ties, they just note it in your records in case the car kills you.:cool:
     
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  10. amos

    amos Active Member

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    Would you please describe the non limp mode? What fix is needed?
    Last week ( about 1000 miles ago). dealer changed HV battery in my car and did s/w upgrade. I was sure my mpg will go higher but instead lower .now city avg is 40mpg and fwy is abuut 47. My tires are on 40psi
     
    #10 amos, Jan 15, 2019
    Last edited: Jan 15, 2019
  11. Mendel Leisk

    Mendel Leisk Sidewalk Supervisor

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    I doubt a battery disconnect is gonna throw off the car's mpg. I purposefully disconnect when doing brake work, and the only odd thing I notice is a distinct rev-up, at the next 2 or 3 start ups, like it's recalibrating throttle response or something.

    I would contact the service manager regarding that fiasco. Also, it could be a factor in your mpg drop. And 90 miles post service visit is not much: per other responders, give it at least a full tank, might just be short trips.

    There have been mpg issues with that, back when the first inverter software update was being applied.
     
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  12. ChapmanF

    ChapmanF Senior Member

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    If some brave souls who are going to have the recall applied (I think I will, just waiting for dealer to get the hang of it first) can use Techstream and note down their current calibration IDs before going in for the update, as described over here, we'll have more and better information.
     
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  13. jack black

    jack black Member

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    this could be easily your answer. prius' MPG reacts to tire rolling resistance out of proportions. i noticed that when i went from stock tires to less LRR tires.
     
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  14. edthefox5

    edthefox5 Senior Member

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    Dealer will lower the tire pressure to door placard lbs. Plus they leave the doors open the whole time they work on the car so the 12 volt battery gets hammered.

    Every time my car has been at the dealer it gets terrible mileage for quite a while.Like audio dave says it takes a while to get it aback to where it was.
     
  15. ChapmanF

    ChapmanF Senior Member

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    They have your battery on a 12 volt shop supply the whole time so it can't get hammered in the middle of reflashing an ECU. Nobody wants to brick the car....
     
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  16. Jeffrey Lee

    Jeffrey Lee New Member

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    YES! I had the exact same issue and question. I lost about 5 mpg after the update. I'd really like to know what the update did.
     
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  17. ChapmanF

    ChapmanF Senior Member

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    Did you retrieve and save the old calibration version numbers from your HV ECU before taking the car in for the recall?

    If not, you'll never know....
     
  18. Jeffrey Lee

    Jeffrey Lee New Member

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    No, you are not required to take the update. They will ask if you want but you can decline with no issue.
     
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  19. Sporin

    Sporin Prius Noob

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    I'm really surprised you guys refuse all these updates and recalls. Be careful out there.

     
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  20. m.wynn

    m.wynn Senior Member

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    As of present, the manufacturer is obligated to notify the owner of a recall but the owner is not obligated to have the recall performed. Simply tell your dealer service writer yay or nay on the recall. She will still gladly take your money for whatever non-recall work you want done.

    Survey: Not Everyone Wants to Require Owners to Get Recalled Cars Fixed
     
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