Prius Traction Control Complaints on the Rise

Seawolf is correct about the tire pressure thing. The higher pressures most people are using (42/40) means less tire conformation with the ground, which means less overall traction. I used to have it set there, but lowered it back to the recommended pressures. Didn't loose any mileage either.

My issue is with the traction control only. I have yet to have a problem with the VSC. That system works fine. the traction control is not though.

 

The last thing I would be concerned with in a Prius is snapping an axle... That requires traction and any car, Prius included, with 500 foot pounds of torque would require "hook" to generate the traction necessary to break drivetrain parts... The tires on a stock Prius will not hold 500 foot pounds of torque, and even if they did... The Prius is not a very "heavy" vehicle... I can't see snapping an axle...

I broke three rears on my Camaro at the drag strip prior to installing a Moser 12 bolt. I never snapped an axle (broke the differentials and gears), and the car was 3600 pounds and had close to 500 foot pounds of torque... (front wheels off the ground)... I just can't see it happening with stock tires in a front wheel drive vehicle like the Prius even if the electric motor was fully unleashed.

 

<div class='quotetop'>QUOTE(Wiyosaya @ Apr 21 2007, 03:17 PM) [snapback]427425[/snapback]</div>

Begging your pardon, I do occasionally have this problem too. The traction control on my Saab 9-5 aero was MUCH less intrusive, and a better system overall. I also used Nokian WR's, and rode snows when we lived in Wisconsin on my Jetta and our Subaru. There is no substitute for snow tires.

I too, wish they would give us the option of turning the bloody TSC off...

Oh, by the way, 25-30 degrees of slope would be about a 33% grade. Our Outback with Nokian's would have trouble managing that in 10" of snow, or snowy weather.

 

<div class='quotetop'>QUOTE(nu2prius @ Apr 22 2007, 08:35 PM) [snapback]428137[/snapback]</div>

That must be that "new" math. A 30 degree slope is over 50% grade. You can figure this without a calculator: the sides of a 30-60-90 triangle are 1, sqrt(3), and 2, and since sqrt(3) is less than 2, the slope has to be over 50%. 1/sqrt(3) is about .58, or 58%. tan(25 degrees) is .46 or 46%.

 

<div class='quotetop'>QUOTE(Wiyosaya @ Apr 21 2007, 02:17 PM) [snapback]427425[/snapback]</div>

The quoted post shows you how lousy the average person is at estimating angles and slopes.

The steepest streets in San Francisco that you can drive up have a slope of 31-32 percent, not degrees. That translates into something around 17 degrees. There is an even steeper street in S.F., but you can only drive down it, not up it. These are among the steepest streets in the world, so it is extremely doubtful your "moderate hill" has a 25 or 30 degree slope.

 

I don't necessarily want the traction control completely disabled, because I think it does serve a valuable protective function for the motors, but with only a bit more programming in the controller, they could implement a real "limited slip" type of algorithm so that the motors and tires are allowed to spin rather than the current behaviour of cutting out completely as soon as slip is detected.. I think this would address most, if not all of the complaints about getting stuck..

As for VSC, I'm still not sure about it.. There have been enough reports of the VSC overriding the steering/wheel power incorrectly and forcing the vehicle to move in the direction of oncoming traffic or off-the-road that I'm sure there is something to it.. It probably does work correctly most of the time, but if there's any chance that it could make the wrong decision, I'd prefer that the car handle predictably in a skid vs. the random variable of what some unknown algorithm is adding to the mix.. Luckily, VSC is easy to disable- simply pull the yaw sensor wire and the VSC will no longer function.

 

<div class='quotetop'>QUOTE(c4 @ Apr 23 2007, 07:05 AM) [snapback]428230[/snapback]</div>

The traction control on the newer models works this way (mostly). If you hold down the gas pedal, the wheels keep turning. It could be better and it's certainly not perfect, but it's much, much better than it was on the older Prius.

I suspect this is a perception issue. The situations where people report something like "VSC took over control and forced me into oncoming traffic" are likely situations where they would have lost control and gone into oncoming traffic anyway. There are physical limitations beyond which no input will control a vehicle. If you exceed these, you are going to go somewhere other than where you intended. Most of the time VSC does its job and you have no idea its even there. If VSC can't keep you out of a skid, you're not going to be able to save it either.

Tom

 

<div class='quotetop'>QUOTE(priusenvy @ Apr 23 2007, 05:47 AM) [snapback]428226[/snapback]</div>

I have no problems agreeing with you about my inability to estimate the angle of the slope.

However, what you point out indicates that the problem can happen on even the slightest of inclines. I note that one other poster to this thread said that they could go nowhere even on their flat driveway.

In my case, the snow was not over 6 inches deep and plenty of other people were able to go up the street at the exact same time under conditions that a Prius could not manage.

IMHO, in some cases, the traction control on this vehicle simply sucks. If it were more of a problem, I would be considering a different model for my next purchase.

Toyota should do something about this.

 

<div class='quotetop'>QUOTE(nu2prius @ Apr 22 2007, 11:35 PM) [snapback]428137[/snapback]</div>

I'm willing to bet that most of the people who were successfully able to make it up the street at the exact same time that my Prius could not manage to go anywhere had something much less capable than Nokian WR's on their vehicles. While the WR's are not snows, IMHO, they are more than adequate for the area in which I live.

I ran tires very similar to WR's, specifically, Vredestein Sno Trac's, for several years on the 94' Integra LS I had before I got the Prius. Under similar conditions, I never had a problem like this where my car simply stopped on an incline because the road was slippery.

IMHO, tires, while they may reduce the symptoms if you go to something other than the stock size, are not the answer to this problem.

And one last thing. I run my tires at factory recommended pressures and adjust tire pressure as required for seasonal temperatures.

 

<div class='quotetop'>QUOTE(priusenvy @ Apr 23 2007, 02:47 AM) [snapback]428226[/snapback]</div>

I guess you're talking about Telegraph Hill?

Anyway, I wondered why he thought 25 to 30 degrees was moderate.

If the coefficient of friction of rubber on ice were 0.4, then the maximum angle you could even park on would be less than 22 degrees. That with all four wheels being braked. If the ice is at all wet, it's going to be much less than that. Under the right conditions (wet ice), I've even found myself sliding backwards in my driveway with just park on. I have to put the emergency brake on too so all four wheels are locked. And that is well under 10 degrees.

Dave M.

 

As the owner of 2 AWD Subarus, I find the overbearing traction control kinda unforgivable. My impreza is fairly torquey (sp?) and it just hooks-up and goes, no matter how wet the street is. The Prius just bogs down and stops on even a slightly wet street. I've only heard about that white stuff..snow? Anyway, a AWD hybrid would be killer, I know the Lexus SUV has it, but don't know how it would work in a Prius. Hopefully Toyota will get it all sorted when the new Hybrid sports coupe is released. One of the best times I had in the Sube, was an autocross where it rained. AWD cars are not that easy to drift, but when it happens..cool. The other side of AWD is that the Subes get only about 25 mpgs on the best of days, double that for the Prius. Oh well.

 

<div class='quotetop'>QUOTE(priusenvy @ Apr 23 2007, 03:47 AM) [snapback]428226[/snapback]</div>

Yup, it's true. As part of a geomorphology class I took in college the professor asked each person in the class to estimate the slope of a well known hill on campus. Most people were throwing out numbers like 50-60 degrees and the like. Then we went out and measured it... 18.3 degrees.

We got tonnes of snow this year and I live on a hilly street. The grade is like 60% or something.

Seriously though, I had some troubles in the prius, mostly the plastic "guards" underneath the car were torn to shreds by the piles of snow. However, it wasn't worse (the traction) than what I experienced with my civic in similar conditions. My front tyres aren't OEM though. They're Toyo something or others (I forget the model). Still they aren't anything special.

 

<div class='quotetop'>QUOTE(tripp @ Apr 23 2007, 02:31 PM) [snapback]428630[/snapback]</div>

Everyone does it. Ask a skier how steep that black diamond run was that they just skied down and they'll throw out a figure so big that snow wouldn't stick to it if it really were that steep. Typical black diamond (advanced) runs are around 30-35 degrees. 45 degrees (100% grade) falls into the category of "extreme". Corbet's Couloir at Jackson Hole is 55 degrees, once you get past the two-story free fall.

Rock climbers do the same thing. 60 degrees is near vertical, 65 degrees is absolutely vertical, and 70 degree is overhanging.

 

<div class='quotetop'>QUOTE(subarutoo @ Apr 23 2007, 03:51 PM) [snapback]428570[/snapback]</div>

This is exactly what I was referring to in my previous post. To me, the Toyota system really barely qualifies as a traction control system. It doesn't do anything that I couldn't do with my foot on the brake pedal.

Like your Subaru, the system in an AWD Volvo or Porsche does not "bog down" when it activates. Sure you may not accelerate as fast as normal, but at least you still are moving. The Toyota simply stops.

Also, someone else posted the VSC being a problem. It's not. When you activate the VSC, you are at the outer edges of control, and the car is doing everything it can to keep you from spinning. If you activate the VSC going around a corner, chances are you were going too fast or too recklessly.

I have yet to activate the VSC in a situation where I wasn't trying to.

 

<div class='quotetop'>QUOTE(dmckinstry @ Apr 23 2007, 11:53 AM) [snapback]428515[/snapback]</div>

I checked and my numbers were a little high. The steepest street in San Francisco that you can drive both up and down is Jones, between Union and Filbert, and has a grade of around 29 percent, not 31. The two streets with 31.5% grade (which you can only drive down) are 22nd between Church and Vicksburg and Filbert between Leavenworth and Hyde.

From http://www.sfgate.com/traveler/guide/transportation/driving/

The Steepest Streets in the City
1. Filbert between Leavenworth and Hyde (31.5% grade)
2. 22nd between Church and Vicksburg (31.5% grade)
3. Jones between Union and Filbert (29% grade)
4. Duboce between Buena Vista and Alpine (27.9% grade)
5. Jones between Green and Union (26% grade)
6. Webster between Vallejo and Broadway 26% grade)
7. Duboce between Alpine and Divisadero (25% grade)
8. Jones between Pine and California (24.8 grade)
9. Fillmore between Vallejo and Broadway (24% grade)
(Source: "San Francisco Almanac")

Also see http://travel.webshots.com/album/556928150JaUQop

 

<div class='quotetop'>QUOTE(DocVijay @ Apr 23 2007, 06:24 PM) [snapback]428664[/snapback]</div>

What I find *very* puzzling is that Toyota is perfectly capable of producing a vehicle with a "real" Traction Control System. I've had my 2007 FJ Cruiser for about a month now, and the Traction Control system in my suv actually does work.

Now that I have two vehicles with Traction Control, the difference is startling. Those of you - I suspect the vast majority - with the Prius Traction Control that actually works well, you should be thankful you don't have a Prius that leaves you stranded.

Sure, it's just a car, you really can't expect 4wd traction in deep snow. But my Dad's 2003 Buick LeSabre had no trouble whatsoever in the same conditions that left my Prius helpless.

http://priuschat.com/Traction-Control-t32150.html

 

<div class='quotetop'>QUOTE(usbseawolf2000 @ Apr 22 2007, 11:20 AM) [snapback]427790[/snapback]</div>

I have an 06 that I got in Jan 06 and have drived in 2 Michigan winters and have never experienced a problem. Maybe I haven't gone up a slippery slope or maybe there is a problem with some but not all traction control. I've had the light blink occasionally when I hit a pot hole, but I've never experienced total shutdown on a slippery surface. I do drive the speed limit but I accellerate gently to try and enhance the MPG. I can't stand flooring it and seeing that yellow bar go to 0.

Steve

 

<div class='quotetop'>QUOTE(IsrAmeriPrius @ Apr 21 2007, 12:35 AM) [snapback]427189[/snapback]</div>

I have a 2005 and I have had no problems in the snow and in the rain.

 

<div class='quotetop'>QUOTE(Bobby @ Apr 26 2007, 11:55 AM) [snapback]430686[/snapback]</div>

Same here with a 2005. I have had more trouble stopping in snow or on wet ice than in going. That was partly because I wasn't expecting it to be so slick and it was on a down grade. There are apparently significant differences, even between 2005s and other 2005s.

Dave M.