Prius Shuts Down In Snow

<div class='quotetop'>QUOTE(ewhanley @ Feb 4 2007, 11:31 AM) [snapback]385186[/snapback]</div>

Your car seems to behave better than many of the others who are posting about their car's problems, but what you describe is still not a particularly good implementation of traction control.

I posted this link in another thread but it's worth mentioning here. This video shows how a well-implemented traction control system should work. Watch the Jaguar going up the iced driveway. No tire spinning, no slipping, no drama. And this is an incline that could not be driven up with traction control switched off, and tires spinning (also shown in the video).

http://stage6.divx.com/members/222398/videos/1044084

Some of you will not be able to view this, I'll try to upload a version to YouTube before the SuperBowl.

EDIT:

Here is the URL for the lower-resolution YouTube version: http://www.youtube.com/watch?v=1tSy5tHtT1g

It's not there yet but should be there in a few minutes.

 

<div class='quotetop'>QUOTE(popoff @ Feb 4 2007, 02:45 PM) [snapback]385167[/snapback]</div>

A very similar situation occured to me a couple of summers ago. A few of us at the office decided to get together for a fishing trip to a tourist camp for 6 days. The tourist camp is located between Kenora and Dryden, Ontario, near a place called Vermillion Bay.

The road to the camp is a winding affair and - in typical Canadian Shield fashion - rolling with many steep hills. The convoy consisted of one co-worker and his wife in a 2003 Lexus LX300 (The same fellow who recently got a 2006 Range Rover HSE), Yours Truly in the Prius, and another guy in his 2005 VW Golf tdi.

The Lexus awd obviously had no problems, and he was in back as he didn't know where to go. I had a very vague idea, so I was leading. The first steep hill was no problem as I was allowed to get a run, but I remembered thinking something was wrong, the Trac/VSC icon was blinking and I really slowed down, despite flooring it. The co-worker with the Golf actually stopped on the hill as he thought I had stalled. He had little difficulty getting going again.

The next hill I was SOL, there was a very sharp turn right at the bottom before the hill, and I barely made it 1/3 of the way up before the car just stopped on me. So VW Golf and Lexus RX300 have to backup and allow me to back down. In no way was I high-centered, the gravel was firm base, but just loose enough that my Michelin Harmony tires couldn't get a grip.

After several runs, including a wild attack that had the VSC kicking in to *really* kill the power, I actually thought of leaving the damn car right there. My co-worker with the Lexus suggested that he could tow me up, so I used the emergency tow eyebolt for the first time. It actually worked well.

And again, the new hire with the VW Golf tdi stick shift had no trouble at all

 

<div class='quotetop'>QUOTE(donee @ Feb 4 2007, 04:31 PM) [snapback]385212[/snapback]</div>

Well, again let's consider the worst-case scenario of the intersection where one side is glare ice and the other side is reasonably dry pavement. Any car or especially an empty pickup truck with "all season" tires and open differential would be fairly helpless in such a scenario.

With high traction studded snow tires, a very minor amount of wheel spin will allow the studs to "grab" and you can accelerate almost normally. Or if you have a "real" traction control system, the brake will apply on the spinning wheel and torque will be transferred to the motionless wheel, and you can accelerate almost normally.

Now consider the best case scenario: an older 4x4 pickup like my 1984 Ford F-150 “work†truck at my hobby farm. I put a Detroit Locker locking case in the front axle, and for the rear axle I removed the spider/side gears and put in a Powertrax LockRite unit. With either the front or rear axle, they are *always* locked unless making a turn, then the faster wheel overruns the gear and it makes a loud CLICKCLICKCLICKCLICK sound.

Now with that same older pickup truck with around 800 lbs in the box for traction weight, I can drive on an icy road with the center portion bare, and never worry about losing traction. I’ll even leave the front hubs in Free to squeeze out an extra mpg or so. If I stop, then accelerate, the wheel on dry pavement will do the work.

I won’t use my 1984 Ford as a daily driver, though it’s reliable enough and very easy to fix if I break it. It’s downright primitive, is lucky to get 12 mpg, the only “power†accessory is the steering and brakes, no A/C, has an aftermarket 4 bbl carb with handchoke, etc.

I would like to point out again that the one time I did bog down this winter, during our Dec 31 blizzard, I should have been in my Ford truck instead. Next time I won’t even question it, but will happily drive the truck the 5-8 km to visit with a neighbor.

With my new studded winter tires, my Prius is finally acceptable as a winter car in my climate, at least during most weather conditions. That’s why I’m seriously considering a 2007 Subaru Outback 3.0 R Premiere Edition as a second vehicle: has a viscous coupled rear axle, VDC, and the ETC works by applying the brake to the spinning wheel

 

<div class='quotetop'>QUOTE(popoff @ Feb 3 2007, 12:10 PM) [snapback]384869[/snapback]</div>

Toyota has already solved the problem beginning with the '06 models.

This TC scenario is a factor with any vehicle on the road that doesn't have a disable switch for TC. Most do some don't. The Prius doesn't but the problem has been solved electronically.

And life goes on...

 

<div class='quotetop'>QUOTE(DeadPhish @ Feb 4 2007, 05:33 PM) [snapback]385324[/snapback]</div>

Typical Prius Apologist post. And wrong too.

See the video I posted. A Prius could not go up that icy driveway. A car with a well-designed traction control system will. And it doesn't require traction control to be shut off. In fact, it is necessary for it to be on in order to reduce power to the driven wheels.

 

<div class='quotetop'>QUOTE(DeadPhish @ Feb 4 2007, 06:33 PM) [snapback]385324[/snapback]</div>

Do you remember where you saw that it was fixed (or how) for 06? I have an 07 that doesn't seem to have the problem. TRAC is too sensitive to be sure, even now, but it doesn't "shut the car down".


<div class='quotetop'>QUOTE(priusenvy @ Feb 4 2007, 06:43 PM) [snapback]385327[/snapback]</div>

We could have a more productive dialog without the finger pointing and labeling.

 

<div class='quotetop'>QUOTE(donee @ Feb 4 2007, 03:31 PM) [snapback]385212[/snapback]</div>

Thanks for the well thought out and interesting post. I thought I had responded earlier this afternoon but, for some reason, I don't see my post.

I knew the word "slippage" would come back and bite me in the a*s, . I was in a hurry and did not pick my words as well as I might have.

Perhaps "lack of traction" would have been a better choice of words than "slippage."

The response I thought I had posted earlier today was more detailed but it's getting late and I need to get some sleep.

I hope to hear back from you.

<div class='quotetop'>QUOTE(popoff @ Feb 4 2007, 11:52 PM) [snapback]385391[/snapback]</div>

 

Hi Popoff,

The video that Jayman posted illustrates my comment perfectly. When the Jaquar is in the ice shed, any slipping at all and there is no getting up the slope. Control things so that at the meer hint of a slip in the first tire, and avoid loosing traction with the second, and the car recovers traction on the second tire, and the car can make the ice grade.

Not sure if traction is a good term for what you are getting at. Traction is that nebulous available force between the tire and the road. Traction is a function of the road, forces on the tire and tire design. A driver cannot change traction or cause traction to be lost. One can cause slippage by overloading the tire above the available static (rolling) traction. One can drive into an area with poor traction. But traction is between the tire and the road, only.

One possible thing to check out regarding this issue, may be that the Prius control speed. That might be due to the CAN architecture and HSD functions also on the same network, rather than the integrated computer architecture and lower packet traffic on the CAN of other cars. If (I am not an expert on the exact details of the Prius) the TC is a seperate computer, and must signal the rate of slip to the Hybrid ECU so it can drop power accordingly. It does that over a packet data network in the car called a CAN, or controller area network. I am not up on the whole CAN technology either, other than to know its a packetized data network, which I have some amateur experience with. If there is allot going on in the network, like variable driver demand, and control negotiation between the Hybrid, Battery and Engine ECU's to configure the system to that demand, a stray packet from the TC ECU might get dropped by collision, or by a controller that does not have enough extra computing speed to accomplish its primary function, and listen to the network, too. Although one would think that something like a CAN network, from its name, it would be prudent to have a collision detect feature in the technology. Even so, collision detect only frees up network time, and the retry methodology of the TC ECU might not resend imediately, resulting in a delay. In which case, the slip gets going big time, maybe too much to recover from. This is all conjecture however, as I do not know enough of the details of the Prius. I make the comment to see if anybody else with more knowledge can show for if this is not an issue.

This does not jive with the poor standing start comments however. A slow standing start is not going to have allot of packet traffic on the CAN. A packet should make it right through. And indeed people report its like the car is turned off, which implies the control is so fast its hard for people to detect its action.

Would be interesting to see if in these standing start situtions if EV works better. Because the engine ECU would not be communicating over the network, and free up some network time.

The gravel road climbing could be a dynamical suspension issue, which is beyond my technical background to comment on. Could the rear suspension be going into a squat dynamically, in a uphill situation, and result in less down force on the front tires? Did you have the BT Tech plate on at that time Jayman?

I have not had anything like this happen yet, although I have had one-tire spins happen on packed snow and the Prius acted similar to the SL2 as far as I can tell. I have driven slowly over ripply refreeze ice on a flat road, again no issue, TC came on , did its thing, the car did not slow down, but would not accellerate either. Hardly could tell it was on, except for the flashing light. I have Hydroedge tires on the car, which with the silica should be more tacky to an ice surface than fully carbon-black tires.The hydroedge tires also have allot of slits (siping), about every 3/4's of an inch around the outside.

 

<div class='quotetop'>QUOTE(donee @ Feb 4 2007, 11:58 PM) [snapback]385395[/snapback]</div>

Hello again. The technical nature of your post is way over my capability to comprehend.

I really don't know what to say at this point except to make the very subjective comment that I have encountered the situations I've attempted to describe.

My son lives in Naperville. We drive up that way several times a year to visit him. Maybe during one of these visits, you and I can get together and discuss the situation at greater length and in more detail.

I'll PM you with my email address.

 

<div class='quotetop'>QUOTE(donee @ Feb 4 2007, 10:58 PM) [snapback]385395[/snapback]</div>

Looking at the video it appears both tires are on the ice, so they're both controlled equally I would think. What's frustrating is when one tire is on dry pavement, yet you can't move.

Well, I don't have specific knowledge of the data traffic on the Prius CAN bus, but I doubt data collisions/retries are the problem. As an embedded software engineer, this is something reasonably easy to detect, and to control, as Toyota uses the INTEGRITY operating system, a pretty decent real-time system that has controls against resource hogging. (Not "soft" real-time like what comes from Microsoft). I think a much more likely scenario is a mechanical limitation, as occurs on any vehicle without individual traction control for each drive wheel. Remember Subaru's slogan - "transferring power from the wheels that slip to the wheels that grip"? That's not a universal technique, by any means, and I would like to have seen that Jaguar with only side of the car on ice, but they didn't show that. (Perhaps on purpose?)

Going uphill certainly transfers some weight to the back wheels from the drive wheels, but from what I've read, this slipping/stopping is seen on nearly level surfaces with slick ice/mud. It just has to be slick enough, but exacerbated by an incline. (So this thread is really mistitled - snow isn't the problem, bare ice is). Also, isn't the BT plate supposed to primarily improve roll/sway in turns (lateral movement, not front-to-back)?

Normally I don't correct spelling on chat sites, but you seem pretty precise about terminology and otherwise use well-written sentences, so:
"allot" = to allocate, distribute
"a lot" = many (it's two words!)

 

<div class='quotetop'>QUOTE(jayman @ Feb 4 2007, 06:20 PM) [snapback]385297[/snapback]</div>

I've been on some of those back roads near Kenora. A fella could get lost back there and never get back out, especially if you were alone and your car wouldn't get up a hill between you and the exit. It could be a week or two before another person would drive on the road. (We stopped going up there after they posted signs saying foreigners (like Americans) couldn't camp in there. Maybe that policy has changed, it's been awhile. There was some kind of argument over fishing rights going on, as I recall). Beautiful rocky country though, Kenora was really interesting with the stores having docks so boaters could come right up.

Sorry about going off-topic, just brought back some old memories.

 

<div class='quotetop'>QUOTE(jayman @ Feb 3 2007, 09:39 PM) [snapback]385010[/snapback]</div>

For a second vehicle, you certainly don't need the latest and greatest Subaru. Trade in the LeSabre for a similar year Outback Sport (about same trunk room as a Prius) and save a bunch of money and some gas. My '99 Outback handled admirably in the snow - a heavy snowstorm was the only time I could beat other cars from a stop light, but then it was like I was on dry pavement! Changing lanes thru a slush ridge was no problem, and I drove it in snow up to the grill, again with no problem (Legacy Outback version had 8" clearance).

Of course, it got 22 mpg in mixed summer driving, maybe 28 mpg on the highway. I've always driven carefully, so that was probably at EPA or above. If Subaru came out with a good AWD hybrid (at least 40 mpg) or electric, I'd buy it in an instant (well, on the next car purchase). They're working on both electric and hybrids, hopefully it will happen sooner rather than later.

 

<div class='quotetop'>QUOTE(nerfer @ Feb 4 2007, 10:44 PM) [snapback]385436[/snapback]</div>

Braking a spinning wheel to transfer torque to its stationary counterpart is an almost universal technique for traction control systems, as it is so cheap to implement. All the parts are already there to implement it. You have to have a computer and wheel sensors for traction control, and the brakes are already there. It's far less expensive than requiring a electronically controlled limited slip differential.

Bosch traction control uses engine management and braking individual drive wheels, so I don't know why you think the car couldn't make it up the ramp with one tire on ice and one on asphalt. It's a far more impressive feat to make it up that ramp with two tires with no traction than with one tire with no traction and one with a lot of traction. Also, I don't know why you'd think a six minute excerpt from a British television magazine would try to test every possible condition for the traction control.

 

<div class='quotetop'>QUOTE(donee @ Feb 5 2007, 12:58 AM) [snapback]385395[/snapback]</div>

Oops wasn't me, I think you mean priusenvy. I did post some videos awhile back after somebody asked a question about how I liked the Powertrax Lockrite in my '84 Ford F-150. Maybe you were thinking of these?

http://www.richmondgear.com/PTRAX.mpg

http://www.richmondgear.com/PTRAX2.wmv

http://www.richmondgear.com/videos/utv.wmv

<div class='quotetop'>QUOTE(donee @ Feb 5 2007, 12:58 AM) [snapback]385395[/snapback]</div>

I do industrial process control for a living, I'm a systems analyst. Among the protocols I've developed on: ProfiBus DP/PA, AS-I, HART, CANBus, Foundation FieldBus, DeviceNet, and ControlNet. There are some differences among the industrial and automotive implementation of CANBus, but nothing that would suggest the sort of behavior you've described.

Starting around a year ago, a lot of the Agilent scopes with "deep" memory depth and very fast sample rate of +2 Gs-s - such as their vector signal analyzers - have been bundled with software that includes CANBus industrial and automotive. I did manage to "borrow" one of our expensive Agilent VSA's from work for a weekend and didn't see anything that would suggest jabber or collisions.

To help you better understand the timing issues of a CANBus system, I've attached a couple of pdf's



<div class='quotetop'>QUOTE(nerfer @ Feb 5 2007, 02:54 AM) [snapback]385438[/snapback]</div>

There are many logging roads around Kenora, Red Lake, Vermillion Bay, Dryden, etc that should be driven with extreme caution. They're built by the logging company and are poorly maintained - if at all. If you should happen to get stuck, or smack a rock and puncture an oil pan, you're a long way from help.

As of last year, if there even is cellular service in NW Ontario, it's analog only. Doesn't do you much good if you happen to own a Motorola Razr.

<div class='quotetop'>QUOTE(nerfer @ Feb 5 2007, 02:54 AM) [snapback]385438[/snapback]</div>

I know what you mean, only "residents" are allowed camping on Crown Land. A Non Resident pretty much has to stay at a tourist camp. It was a cheesy attempt to bolster the tourist camp industry in that region.

The policy backfired as - let's face it - most of the tourist camps are crappy and WAY overpriced. Like you're supposed to drop +$1,800 a WEEK.

Same as fishing, a Non Resident pretty much has to stay at a tourist camp to get the license. It's a load of horse s***

<div class='quotetop'>QUOTE(priusenvy @ Feb 5 2007, 06:12 AM) [snapback]385452[/snapback]</div>

That's what has me so frustrated! The car already has ABS, even if it's only a three-channel system. It would be almost brainless to apply torque management and pulse the brake on the spinning wheel. My Prius has VSC so it's already capable of pulsing an individual front wheel to "correct" your direction.

 

<div class='quotetop'>QUOTE(donee @ Feb 4 2007, 10:50 AM) [snapback]385126[/snapback]</div>

I agree and disagree with your comment. How's that for an answer?

I agree spinning tires will do you no good on glare ice if your tires are studless. In fact, the small amount of friction from the tire rubbing on the ice will actually make it worse by melting the ice. The liquid on top of the ice makes it even more slippery and compounds the problem. Try holding a fresh icecube out of the freezer versus an icecube that's been sitting in water.

Spinning tires in any type of loose surface (deep snow, mud, gravel, sand) is actually beneficial if you have the right type of tires. Dedicated snow tires have very a aggressive tread pattern with exceedingly deep tread (15/32" typically) designed to handle deep snow. With each rotation of the tire, the tread pattern digs into the snow and can freely evacuate it out of the way. The goal being to reach the pavement underneath to gain optimal traction.

In extreme cases (e.g. deep mud and sand), M/T (Maximum Traction) tires work by having the tires spinning. The best analogy I can think of is a paddle boat. The paddles push the boat forward by displacing some mass (e.g. water). M/T tires work the same way by displacing the mud.

In my situation with the parking lot at my daycare center, I'm certain my problem wasn't being "hung up" on top of the snow. I could easily back up with no problem at all. My problem was the TRAC system preventing my Blizzaks from displacing snow in the snowpile in front of me.

 

<div class='quotetop'>QUOTE(automatic1stdown @ Feb 5 2007, 09:54 PM) [snapback]385929[/snapback]</div>

In many cases, it is not possible, or even necessary to grind your way through the hard pack down to pavement. According to an article I read in Road & Track magazine, if you can't get down to the pavement, the next highest coefficient of friction is snow-on-snow. So in this situation what you want in a snow tire is for a thin layer of snow to adhere to the tire, to take advantage of the snow-on-snow contact.

 

Hi Jayman, Priusenvy, Nerfer and Popoff

Ok. Yea, get too tired staying up late on the weekends to make perfect sense.

Thanks Priusenvy for the video posts.

Ok, if its not packet problems, it might be ECU processor underun, still. My MFD was very wacky today in the cold weather (-10 F startup in the morning - thank God for the block heater). Almost like it got 5 to 10 seconds behind the car. Do you guys up in Canada see that at all? Was sitting at a stop for ten seconds with the MFD telling me the HSD was configured for running down the road. First time I have seen that. The only other weird cold weather thing is that around 15 to 25 F there is a point in the car's warmup that it will glide up to 45 mph, rather than the usual 41 mph limit.

Nerfer, I hope I was not too confusing. I meant to say " recovers traction on the first tire" .

On the BT Tech plate, my thought was that there are significant side loads on the chassis in deep gravel, or on rutted dirt roads. Having had the "wild ride" experience entering a turn too fast in Prius without the BT Tech plate (this was at slow speed), I can only imagine that situation happens allot when the car is crabbing in gravel, or running a wheel down a rut on a dirt road. The VSC would then start going hyperactive trying to control the non-linear stock (BT-less) Prius chassis. I do not have VSC on my car, but know that it uses a yaw sensor and steering wheel sensor, and if the two do not match, it starts up. Jayman did say he had VSC triggering during his episode on the back roads.

 

<div class='quotetop'>QUOTE(automatic1stdown @ Feb 6 2007, 12:54 AM) [snapback]385929[/snapback]</div>

This is very strange. I've never had a problem in parking lots from traction control in any snow conditions. I have had to rock the car or shovel out to get out past a plow snow pile, but it was due to the low ground clearance and not the traction control. When the snow is a foot deep I get out the shovel! 4 inches or a snow pile at 8 inches deep no problem to just push through.

In fact the car has never had a problem in snow. The only times I've seen the traction control kick in and cut engine power was on smooth glare ice that was also wet!

 

well its winter here in norway too, i have not had any serious problems with the winter here in oslo or the much more snowy conditions in the countryside. But the prius "anti-spinn" behave different in when its slippery with ice or simmilar compared to the BMWs i had before.

When the prius 2006 version is moving in a ok low speed , it work very well in snowy slippery conditions.Its the stopping then starting part that sometimes make me a bit nervous. Good winter tires is alfa omega on this car (should be on every winter used car, lol) i use the Nokian hakkapeliitta RSi wintertires, works verywell on this car.

But id prefer that the weels was spinning slowly when its stuck or cant get up a hill instead of not moving. that would prevent the psychological feeling of that it would make it even if it wouldnt.

also id been abit suprised when im starting up from a crossing and im a bit in a hurry, and the road condtion is a bit mixed , good grip and bad grip. if i give the car a bit too much trottle then it might get into the mainroad---then detect its spinning a bit----then turn of power ALOT (but the car is in movement and i moved to grippy road --- then power comes back... feels like its a bit too much power OFF before it tries again...
other cars i had have kinda same problem but havent been that hard on cutting power.....more smooth in a way.

I have a pair of autosock in the trunk just in case (nice for the prius since its all around the tire, no none grip spaces as on chains) but i havent needed them for real yet,, just tested them ...
http://www.autosock.no/ , toyota actually now delivers Snowcap on selceted models, snowcap is made together with autosock.

cheers
Andreas

 

wow, autosocks looks like a cool idea. does the car have to be jacked up to install?