Traction Control question

Were there any small potholes or bumps in the road? The symptom you describe happens to me all of the time when ABS kicks in and potholes are usually the culprit. It works like this:

-You're decelerating using regenerative braking when you hit a bump.
-The car senses one of the wheels slipping so it goes "oh, crap, time for ABS!" It doesn't take much of a bump for this to happen. (Obviously, just a wet road could do it under the right circumstances.)
-It immediately kills regenerative braking and goes to friction brakes instead, which can be noticed by the driver. Feels like it lets go for a half a second and then grabs.
-You complete your stop under friction brakes and eventually the computer reverts to normal operation with regenerative braking. This can take a minute or two.

Does this correlate to what you experienced?

 

Try lowering tire pressure. What psi do you have now?

 

<div class='quotetop'>QUOTE(Phred @ Jul 22 2007, 04:00 PM) [snapback]483233[/snapback]</div>

The Goodyear Integrity OEM tires are bad. If you still have those, you will get a lot of traction issues. Otherwise, what you described is normal. The Prius was loosing traction during regenerative braking, which is done with the front tires only. Wet pavement, sand, gravel, or bumps can cause the tires to loose traction. We see it around here with the snow and ice in the winter.

Tom

 

<div class='quotetop'>QUOTE(qbee42 @ Jul 22 2007, 06:36 PM) [snapback]483290[/snapback]</div>

I would like to see some experimental evidence to back this statement.

 

<div class='quotetop'>QUOTE(qbee42 @ Jul 22 2007, 03:36 PM) [snapback]483290[/snapback]</div>

I wouldn't go so far as to say they are "bad" tires. I'd say they are good for only about 30,000 miles.
. . . then, when you go out and get new tires (hopefully not Integrities :blink, you will find many of the minor Traction Control occurrences will disappear. At least that was my experience.

Oh, by the way, I too have had the Trac do the same thing on wet hills in San Francisco with the Integrity tires. I'm glad I no longer have those POS.

 

This isn't the traction control, it's the anti-lock brakes. Traction control activates when you spin a wheel under power. It's normal for ABS to cut in -every time- you skid a tire. Time after time, if necessary. The car shudders because a wheel skids, then grips, then skids. Nothing to worry about. If you live in San Fran and are worried about it doing this, get better tires. Rain tires or tires that have a lot of "siping" will work better in this environment. Tire pressure will have only minimal effect.

While a lot of people don't like the Goodyear Integrities, they aren't "bad", just cheap. Most replacements work better. I have only skidded my new Integrities once so far. I do plan to replace them this fall with Nokian WR tires. Now -they- would work well for you on wet roads.

 

ABS and Traction control invoke antilock by "pulse modulating" the brake hydraulic pressure to prevent total lockup of the wheel compared to the other wheels. This causes a "Jittering" effect when this happens. You really have to stomp the brakes hard to make this happen.

As for the Goodyear Integrity, you can read the crappy 460 treadwear value right on the side of the tire. This is about as low as you will see with a major OEM tire. The high end tires have treadwear values of 760 to 800. As far as experimental evidence, they are in a tire dump, since I experimented with Low Rolling Resistance Tires that wore out fast since the treadwear values were never better than 500. After that expensive lesson with fast wearing tires, I learned about treadwear ratings and have been amazed at how long the 740 to 800 rated tires last.