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Need Help QUICK! MPG dropped BAD and high RPM!

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by F8L, Apr 9, 2011.

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  1. F8L

    F8L Protecting Habitat & AG Lands

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    Me too. I just couldn't believe something like a bad tire could cause so much of a problem.

    I drove for 30 miles on a fairly flat freeway today. Just cruising at 60mph- 65mph and ended the trip at 58.3 mpg. I have about a half mile of surface streets so between a nice off ramp glide and some pulse and glide through the neighborhood the mpg jumped by about 1.5mpg. So there is definitely nothing wrong with the car. The nut behind the wheel is another story. :)
     
    #41 F8L, Apr 15, 2011
  2. Tideland Prius

    Tideland Prius Moderator of the North
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    lol. I just want summer. We were tempted with 59 degree highs on Tues and we just got dumped with 4 inches of wet snow. Ugh.
     
    #42 Tideland Prius, Apr 15, 2011
  3. F8L

    F8L Protecting Habitat & AG Lands

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    Not that our winters compare but we recently started seeing sunny days with temps in the 70s and I got all excited then it turned cold over night and the rain came back. Today was nice though. I'm wishing you warm weather, my friend. :)
     
    #43 F8L, Apr 15, 2011
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    F8L, it would be great if you could have your tire shop examine the interior of the 17" tires and figure out exactly what is wrong with them. I'm interested to know how many tires have a problem and what is the nature of the problem.

    If the fault is visible, please take sharp photos and post.

    You had reported that the tires hold air pressure and do not show sidewall bulging or other obvious damage. Since they were producing noise, maybe a tire was coming apart from within?

    From time to time an owner reports a sudden mpg decrease and the usual suspects don't produce any results. If you can document what is wrong with your tires, that will add new knowledge to the community!

    It would also be good to know how many miles had been logged on those tires at the time that the noise and increased drag started.
     
    #44 Patrick Wong, Apr 15, 2011
  5. F8L

    F8L Protecting Habitat & AG Lands

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    Definitely! I cannot afford new 17" tires right now or the near future but when I have the new ones installed I am going to have the tire shop look the old ones over and I'm going to take pictures or any damage we may find.

    I've had these tires since 2006 so they are a bit long in tooth even though they still have some tread left. I regularly swapped back and forth between the stock setup and the 17's because I can't stand the MPG drop but I love the looks and handling.

    My guess is either a tire is coming apart internally or I bent a wheel and it is not visible. Either way I will find out and document the issue as well as update the first page of this thread.

    Thanks for all your help, Patrick.
     
    #45 F8L, Apr 15, 2011
  6. Hal W

    Hal W New Member

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    Why are you running 17" tires on a a FE machine in the first place? Hal
     
    #46 Hal W, Apr 15, 2011
  7. wick1ert

    wick1ert Senior Member

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    If you're still having the RPM revving issue, maybe you can talk to peef and see if he can ride with you and run some techstream charts, graphs, etc. to see what is actually going on. Not sure if you two are close to each other, but pretty sure he's in CA (I know it's a large state, but never know). I'd offer, but you're 2000 miles away from me.
     
    #47 wick1ert, Apr 15, 2011
  8. F8L

    F8L Protecting Habitat & AG Lands

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    The difference in looks and handling are pretty significant. The handling is so improved that it feels like a completely different car. Taking 30mph curves at 60+mph is cake!

    The RPM issues are gone. I thought it may have happened after I swapped back to the 15s but I think it was due to the elevation change on a section of road. I appreciate your offer though. That's what I like so much about this forum. So many people willing to help each other out. :)
     
    #48 F8L, Apr 15, 2011
  9. Hal W

    Hal W New Member

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    I was going to mention elevation change ,but thought better of it! <grin> Hal
     
    #49 Hal W, Apr 15, 2011
  10. F8L

    F8L Protecting Habitat & AG Lands

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    You're on top of things, as always. :D
     
    #50 F8L, Apr 15, 2011
  11. Tideland Prius

    Tideland Prius Moderator of the North
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    Thanks! I'm aiming for 60 with this car (was close last year) and maybe finally the rated 64mpg city next summer.
     
    #51 Tideland Prius, Apr 15, 2011
  12. F8L

    F8L Protecting Habitat & AG Lands

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    Finally got around to having my wheels and tires checked. I had them put on the balancing machine and its turns out one tire is starting to cup. They must have balanced it because when I put the wheels back on, the thumping noise and vibration is gone. The car drives like normal now. Maybe that wheel was way out of balance?
     
    #52 F8L, May 6, 2011
  13. bisco

    bisco cookie crumbler

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    they aren't nokians, are they?:D
     
    #53 bisco, May 6, 2011
  14. F8L

    F8L Protecting Habitat & AG Lands

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    Nope. :)

    They are cheap Kumho Ecsta ASX. They are also 5 years old!
     
    #54 F8L, May 6, 2011
  15. sipnfuel

    sipnfuel New Member

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    So that was the problem all along?
     
    #55 sipnfuel, May 6, 2011
  16. F8L

    F8L Protecting Habitat & AG Lands

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    I'm afraid to answer that. It is really weird that an out of balance tire can cause those symptoms but it seems fine now. Crazy.
     
    #56 F8L, May 6, 2011
  17. sipnfuel

    sipnfuel New Member

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    It's interesting how much energy was being transferred/lost in that way

    Maybe you lost a weight after so long, especially if it was the self adhesive kind. Maybe it fell off mid-trip.
     
    #57 sipnfuel, May 6, 2011
  18. F8L

    F8L Protecting Habitat & AG Lands

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    The weights are the adhesive type. I wonder if it was so off that it caused the cupping they mentioned. The thump was very pronounced.
     
    #58 F8L, May 7, 2011
  19. savrip

    savrip Junior Member

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    Glad to see your problem work out F8L. I'm having a similar issue, so it was interesting to read through your and look for a solution. Unfortunately I don't have one yet. My issue is ScanGauge II is reporting current MPG about 10MPG less then than the main display is. This is giving me 10MPG average lower, but compare it to the dash monitor and it appears to have no change. From process of elimination it would appear that the ScanGauge needs a reset. I unplugged it yesterday for several hours with no improvement. I guess I'll reset to default next and see if that helps. I wanted to check around and see if anyone else had been seeing this.
     
    #59 savrip, May 9, 2011
  20. F8L

    F8L Protecting Habitat & AG Lands

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    My SGII was working well at the time and my dash display was in sync. Are you having the same problem with the tires going thump thump thump down the road? :)
     
    #60 F8L, May 9, 2011
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