Prius Prime Plus in my hands

Discussion in 'Prime Main Forum (2017-Current)' started by bwilson4web, Jan 19, 2017.

  1. GT4Prius

    GT4Prius Active Member

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    Do you have 15 inch wheels?

    How do you find the ride quality with tyres at 10 PSI over? Compared with the Toyota recommended?

    And tyre wear? Its that even across the tread or greater around the centre of the tread?

    And grip? In theory much less rubber on the road.

    Any risk of probs with your insurance co if your car was in an accident and they examined it afterwards?

    (I suppose the alternative, for those who have patience to do it, is to over inflate, set the TPMS, and then reduce the pressure, taking into account the margin of error that they require).

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  2. bwilson4web

    bwilson4web i3 and Prime

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    Yes.

    How do you find the ride quality with tires at 10 PSI over? Compared with the Toyota recommended?
    The tires transmit more of the road surface imperfections. So if driving on gravel roads, a lower pressure might be a little nicer. But my travel is on paved roads and I prefer to lower rolling drag and more precise handling. I'm actually using race car techniques.

    The USA 'racing' magazines have a lot of articles about how to tune tires and suspensions for race day. I use an IR camera to check alignment and tread temperatures:

    [​IMG]
    These are a little difficult to interpret as the rear tire photos are taken from the rear and the front tire photos from the front, flipped 180 degrees. The inserted strip is to compare tread temperatures with the opposite side tire. The "Driver rear, 1/64" and "Passenger rear, 1/32" are the shims I used to take out excessive tire camber that was wearing heating and wearing out the outer treads. I should have used 1/32" shims on the driver side. The passenger side camber is still excessive but requires a different approach.

    And tire wear? Its that even across the tread or greater around the centre of the tread?
    The modern, belted radials, it is all but impossible to get center wear. But as the pressure increases, I tend to take turns a little faster and with the alignment I like to use, it can wear the outer most tread a little more than center but not excessive.

    In the USA we typically use 1/32" (0.03125" or 0.79375 mm) to measure the tread depth (the grove depth compared to the tread surface.) By the time the edges reach the wear bars and local limit ~2/32" (~1.5875 mm), I see the middle grooves in the 3/32" - 4/32" range (2.381 - 3.175 mm). But these are enforced independently by the different States and the ones in Dixie and rural states are more 'casual' about enforcement. You can get a ticket but probably because you pissed off the cop.

    And grip? In theory much less rubber on the road.
    Less rubber but at a higher pressure that can also reduce hydroplaning. But the biggest advantage is the tires flex less reducing the heat build-up. That heat comes at the cost of higher rolling drag.

    Many years ago there was a 'Firestone Ford' problem of big fat tires whose low pressure meant they warmed up too much. This led to a number of fatal, tire blow-out accidents from both too much tire heat and poor Firestone tires.

    Any risk of probs with your insurance co if your car was in an accident and they examined it afterwards?
    Not really as the accident investigation would have to measure the tire pressure soon enough and be able to show in court that it caused the accident. A crashed car is not going to have the same dimensions as the pre-crash version. Usually the 'nut behind the wheel' is the root cause.

    BTW, higher tire pressure shortens braking because the rubber in contact can support a greater braking force. Of course this depends on the road surface and all bets are off with snow and ice. Personally, I think tire chains are the right answer in those conditions but I live in Dixie, a more temperate climate.

    (I suppose the alternative, for those who have patience to do it, is to over inflate, set the TPMS, and then reduce the pressure, taking into account the margin of error that they require).
    My understanding is other countries, especially the EU ones, are more anal about checking vehicles and tire pressures when the police stop them. If your local driving regulations specify a range limit, I would set the TPS to the minimum plus 10 psi and if over inflation is rigorously enforced, reduce it to just 1 psi over knowing it will quickly decay.

    Bob Wilson
     
  3. GT4Prius

    GT4Prius Active Member

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    V v interesting! Thanks Bob.

    Just a thought from what you said about heat. The heat that is generated from greater flexing at lower pressures: is that sufficient to raise the tyre pressure significantly, if so, by how much?

    Also does that mean that the problem is self limiting because as the temp rises, the pressure increases and the flexion reduces?

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  4. Trollbait

    Trollbait It's a D&D thing

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    The tire pressure will increase by 2 to 3 psi with driving. In the case of a low tire, the rubber would fail from heat before the air inside got hot enough to raise the pressure up to normal.

    In the Firestone-Ford case, the failing tires were under inflated, which means severe sidewall flexing. This underinflation happened because most people(in the US) don't check their tire pressures, and an underinflated tire doesn't look much different than one at what the car manufacturer recommends. Having lived with some slow leaks, I've had tires at 25psi that look like the same at 35psi. So now we have TPMS on all cars.

    A set of tires on the HHR suffered center wear out, and IRRC, they were set to about 2 psi over the sidewall 44psi. From an accidental dirt/flour test, I know the outside tread of the rear tires on the Sonic are off the pavement when over 42psi.
     
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  5. bwilson4web

    bwilson4web i3 and Prime

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    Our BMW i3-REx measures both pressure and temperature. Although the pressure does go up, it is not enough to limit further temperature rises nor enough tire pressure to avoid the problem. I'll try to take some before and after pictures later.

    Bob Wilson
     
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  6. bwilson4web

    bwilson4web i3 and Prime

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    Had the transaxle oil changed today, $139.34:
    • $95.96 - labor
    • $40.65 - parts
    They notice the higher tire pressure and asked if I wanted it changed. In contrast, Toyota would just deflate the tires and reset the TPS. I am pleased.

    The sample is more opaque than virgin oil. It smells a little like gasoline but no paraffin odor:
    [​IMG]
    This is with 5,000 service miles.

    Off to the oil testing lab this afternoon.

    Bob Wilson
     
  7. bwilson4web

    bwilson4web i3 and Prime

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    Now I'm pissed at Entunes:

    Trip A - no problem, the current trip:
    [​IMG]

    Trip B - no problem, the current tank of gas:
    [​IMG]

    Odometer - no problem on miles but the MPG is wrong! Last week, ~112 MPG:
    [​IMG]

    Entune "ECO", when I hit "Update", it started a new bar graph and RESET the Odometer MPG:
    [​IMG]
    If it has just started a new bar and left the ODO MPG as a lifetime, no problem. But to reset the ODO too, that made me unhappy.

    Bob Wilson
     
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  8. Prodigyplace

    Prodigyplace Senior Member

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    @Prius Team Bug or feature?
     
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  9. bwilson4web

    bwilson4web i3 and Prime

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    The transaxle oil results are back and I could not be happier:
    • Silicon 59/67 = 88% :: the silicon comes from the case sealant.
    • particle 6/ml 2109/6265 = 33% :: excellent particulate reduction.
    • particle 14/ml 10/49 = 20% :: even bigger particles, sealant beads, are going away.
    • 40C viscosity 2k mi (24.6 - 24.0) / 24.6 = 2.4% shear down
    • 40C viscosity 5.4k mi (24.6 - 23.2) / 24.6 = 5.6% shear down
    Based on these numbers, the next logical change and test would be 25-30k service miles. We've already reduced the particulates significantly which are a point source for oil strain.

    The reduction in boron suggests boron nitride may have been used in assembling the transaxle. The dilution would be expected as the coating material leaches out of the bearing surfaces. Also the calcium and phosphorus levels staying constant suggest these additives are NOT being consumed.

    If you haven't changed your transaxle oil, we could use a sample from at least 15k service miles, more is better. My expectation is we'll see the viscosity shear down closer to 15%, the nominal limit of oil service life.

    Bob Wilson

    ps. Virgin sample metrics: 2003 Prius - Cold Weather and Transaxle
     

    Attached Files:

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  10. GT4Prius

    GT4Prius Active Member

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    #510 GT4Prius, Nov 1, 2017
    Last edited: Nov 1, 2017
  11. jerrymildred

    jerrymildred Senior Member

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    I can see why! It may be that someone doesn't care about lifetime mpg and it would be nice to use ODO mpg for tank by tank mpg and use A & B for other things, but having the lifetime mpg is really cool. Perhaps the car should come with an adhesive warning label that you can peel off once you get the message to not do that. Or, better yet, a pop up warning when you hit "Update" reminding you that it will reset ODO mpg. Then you could confirm or cancel.
     
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  12. bwilson4web

    bwilson4web i3 and Prime

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    I took the car in for a six month warranty service and we found:
    Left Right metric
    1 -0.3 -0.6 front camber
    2
    -0.9 0.6​
    -0.9 0.6
    front specs​
    3 0.11 0.07 front toe
    4
    -0.03 0.15​
    -0.03 0.15
    front toe specs​
    5 -1.5 -1.2 rear camber
    6
    1/64"​
    1/32" rear camber shims
    7
    -1.7 -0.2​
    -1.7 -0.2
    rear camber specs​
    8 0.02 0.02 rear toe
    9
    -0.01 0.18​
    -0.01 0.18
    rear toe specs​

    Based on these metrics, the shims were definitely needed. Per my earlier speculation, I should have used 1/32" on both rear wheels.

    PROBLEMS:
    1. The service center primary tire alignment tool, a Hunter, at Decatur (SouthEast Toyota Region) does NOT have the VIN associated table to take a measurement. To Serra Toyota's credit, they had a senior tech take the measurements manually and not charge me for it!
    2. The rear camber on our Prius Prime Plus was badly off, excessive negative camber. I repaired it with metal shims but I have not figured out how to get this information into the 'powers that be.'
    I wrote it up and e-mailed Toyota using their web interface (#171202-000009). I cited by name the service writer who solved the alignment measurement problem of their Hunter. I also attached a copy of my oil testing results. Hopefully, @Prius Team might take a peek at it too.

    Bob Wilson
     
    #512 bwilson4web, Dec 2, 2017
    Last edited: Dec 2, 2017
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  13. bwilson4web

    bwilson4web i3 and Prime

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    I'm working on adding an Azdome GS63H and ScanGauge II. Although bought via Amazon, the GS63H appears to work reasonably well and their support page has the User Manual. However to extract the GPS data, I'll need their special viewer which so far, only the Windows downloads. As described in their manual, I've sent e-mail requesting it.

    Later today, I'll be working on mounting that hopefully will let me read out the center console screen values, avoid direct sunlight, and some part of the windshield. My first attempt will be mounting on the passenger side, head rest. This solves all three requirements but reading the trip metrics may be a problem. On the dash, I'll have a direct sunlight and cable problem as well as challenge to get any part of the screen.

    Right now, it is "watching TV" so I can get some video test files to make sure I can process them. I'm using 10 minutes per file since that avoids any 'data gaps.'

    The ScanGauge II, upgraded for tire pressure, works except for 'sleep', where it goes into low-power, no display mode. The 'Gas' type is set to 'hybrid' but my 'sleep' tests:
    • COM - stayed on over night, not off.
    • VOLT - turned off while driving, too soon.
    • RPM - uh, it is a hybrid.
    I'll re-RTFM and hopefully figure it out.

    Bob Wilson
     
    #513 bwilson4web, Dec 3, 2017
    Last edited: Dec 3, 2017
  14. bwilson4web

    bwilson4web i3 and Prime

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    Fifth tank: 2176.8 miles for 10 gallons.

    I briefly thought about running the tank dry but I've already done that experiment. I refueled on the "low gas" indicator which suggests ~1.4 gallons remained but other tests have shown closer to 1.0 gallons.

    I also got the correct Xgauge definitions from support:

    Using the following link » X-Gauge Categories » Toyota / Lexus / Scion TPMS Method 2 you will find the XGauges for the Tire Pressure. ...

    Cristina Bollinger

    Thank you Cristina!

    Remember you need the latest firmware which requires shipping it back.

    Bob Wilson
     
  15. bwilson4web

    bwilson4web i3 and Prime

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    Over 90% of the time, dynamic cruise control works great. But something curious happened today on a drive home:

    Use "," to backup a frame and "." to advance a frame. You may want to mute the podcast audio.
    • Car in left lane moved in front, still safe distance. I'm at 63 mph.
    • Brake lights came on, waiting for dynamic cruise control to slow Prius. Speed to 60 mph.
    • "Holy Sh*t" coming close, hit the brakes to regain safe distance and speed 52 mph.
    These automated systems handle a lot but the driver still has to keep alert. Traffic merging from the right, no problem. Just this one case emphasized the driver is still responsible.

    Bob Wilson
     
    #515 bwilson4web, Mar 5, 2018
    Last edited: Mar 6, 2018
  16. DavidA

    DavidA Prius owner since July 2009

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    Curious? Nah. Probably just a whole lot of water interrupting/deflecting the radar signal. I believe that's covered in the manual. This is why automated systems scare the he** out of me.
     
  17. bwilson4web

    bwilson4web i3 and Prime

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    If we number the lanes:
    1. Fastest inner lane and HOV
    2. Next high-speed lane
    3. Lane I'm in, slightly slower lane
    4. Exit and entry lane adjacent to shoulder
    During rush hour, speed and lane discipline falls down. In effect, it is a like a row of sprinters and everyone is going as fast as possible in their lane. Apparently 'the driver' who made my day was in lane #2 but wanted to drive at speeds of lane #3 but not yet ready for lane #4. It may have been been the wet road. Regardless, there is no traffic in front of 'the driver' so they were backing up traffic behind them.

    A large SUV style vehicle had to brake to avoid running into 'the driver.' At this point, they decided to change to lane #3, in front of me. I had been slowly catching up to leading traffic in #3 when 'the driver' signaled and pulled in front. Only now 'the driver' had half the following distance but with a goal of driving slower.

    My expectation was even if the vehicle speed difference was not detected, to see a distance triggered BRAKE warning. It didn't happen. I was also expecting a more aggressive, automated, speed reduction that I'd seen before which also did not happen.

    We were closing at what the video suggests was ~3-4 mph. Manual braking from 60 to 53 mph quickly reversed the closing rate and 'the driver' was soon going further away. When I re-engaged dynamic cruise control, everything worked as expected.

    The optically based, BMW i3-REx had taught me to be alert to sensor induced dropout. I had hoped the radar based, Prime would be more resistant.

    Bob Wilson
     
    #517 bwilson4web, Mar 6, 2018
    Last edited: Mar 6, 2018
  18. Lee Jay

    Lee Jay Senior Member

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    Millimeter wavelength radar doesn't penetrate rain water well at all.
     
  19. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    A system that maybe works is worse than no system at all?
     
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  20. Lee Jay

    Lee Jay Senior Member

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    Not even close. I've used it on virtually every drive for the last 11 months and I've had it fail twice - once in heavy rain, once when the front of the car got covered by a heavy snow/slush mix. Both were predictable, and the other 99.5% of the time it has worked extremely well.
     
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