Bizarre Traction Control Behavior?

TooFolkGR · 06-26-2007, 10:36 AM

I've got a New 2007 Prius with about 3,000 miles on it. The other day (Saturday) I was stopped at what we call a "Michigan U-Turn" here in Michigan. It's where you have to go past an intersection then do a U-turn to turn right at the intersection instead of making your usual left.

Anyway it was a warm day, probably 91 degrees. I had the air conditioning running, but when I stopped at the Michigan U-Turn my engine shut off (which is pretty typical.)

When the light turned green and I pressed on the accellerator, the car started lurching. Really lurching, not unilke a regular car does when it's running out of gas (yes, I have had that happen to me). Of course I had a full tank of gas and wasn't pressing down on the accellerator very hard. It lurched for about 50 feet, at which point one of the orange lights on the display started flashing. I -think- (though I'm not sure) it was the Traction control signal with the wavy lines behind the car.

Any possible explanation for this? It hasn't happened since. The only reason I suspect the traction control is that in a couple other situations (where I went over bumps and one tire left the road for a split second) that light has flashed at me. I don't have any reason to believe I was going over a bump though, and the car lurched as never before.

I am still under warranty; worth getting checked out?

qbee42 · 06-26-2007, 11:27 AM

If it was a yellow indicator, it was probably the traction control. Most likely it was doing what it does, which is keeping the wheels from spinning. There must have been something slippery or loose on the road surface.

Tom

TooFolkGR · 06-26-2007, 11:41 AM

<div class='quotetop'>QUOTE(qbee42 @ Jun 26 2007, 11:27 AM) [snapback]468277[/snapback]</div>

Quote:

If it was a yellow indicator, it was probably the traction control. Most likely it was doing what it does, which is keeping the wheels from spinning. There must have been something slippery or loose on the road surface.

Tom
[/b]

That seems like the most likely explanation to me too, the only thing that gives me doubt was that it lurched along for like 50 feet before it stops. I checked my tires when I pulled into the parking lot to see if I could see anything on them, but there may have been something very fine and granular on the road surface I suppose.

Thanks

priussoris · 06-26-2007, 12:20 PM

The traction control is the only thing that I don't care for in the prius.
We took a trip down to the Ozarks last weekend and had a lot of hilly gravel roads with pot holes and motorgrader grooves etc... it took a while to get up the hills had to go very slow, a little faster and 1 wheel spins and t/c takes over.
But if that is what it takes to keep mg1 in good shape so be it.

donee · 06-26-2007, 01:14 PM

Hi All,

Since I have never seen a wavy line car symbol, I bet that is the VSC symbol, not the TC symbol. And the action of your car tends to confirm that, in my opinion. My car only has the TC.

Get the alignment checked, and I would add a BT Tech plate, or other rear-end stiffening/dampening device. One test is find some open asphalt, and try to pull too tight a turn at say 15 mph. The car should understeer and the tires slide, and scrub off speed. If the car tends to get a mind of its own, and kinda wiggles to the right, in a left hand turn, and not scrub off speed, its probably alignment or rear end flex. Talking a little out of my expertiece here, but give it a try.

What I think happens in tight turns is the back end flexes, and steers the car in oposition to the front of the car. The VSC sensors detect this, and VSC kicks in to try to straighten out the manuever. Of course, your trying to turn. At slow speed, this has a dramatic lurching behavior, as individual friction brakes are being pulsed.

qbee42 · 06-26-2007, 01:23 PM

<div class='quotetop'>QUOTE(donee @ Jun 26 2007, 01:14 PM) [snapback]468369[/snapback]</div>

Quote:

Since I have never seen a wavy line car symbol, I bet that is the VSC symbol, not the TC symbol. And the action of your car tends to confirm that, in my opinion. My car only has the TC.
[/b]

They use the same symbol, plus the VSC chimes if pushed too far.

Tom

TooFolkGR · 06-26-2007, 03:14 PM

<div class='quotetop'>QUOTE(donee @ Jun 26 2007, 01:14 PM) [snapback]468369[/snapback]</div>

Quote:

Hi All,

Since I have never seen a wavy line car symbol, I bet that is the VSC symbol, not the TC symbol. And the action of your car tends to confirm that, in my opinion. My car only has the TC.

Get the alignment checked, and I would add a BT Tech plate, or other rear-end stiffening/dampening device. One test is find some open asphalt, and try to pull too tight a turn at say 15 mph. The car should understeer and the tires slide, and scrub off speed. If the car tends to get a mind of its own, and kinda wiggles to the right, in a left hand turn, and not scrub off speed, its probably alignment or rear end flex. Talking a little out of my expertiece here, but give it a try.

What I think happens in tight turns is the back end flexes, and steers the car in oposition to the front of the car. The VSC sensors detect this, and VSC kicks in to try to straighten out the manuever. Of course, your trying to turn. At slow speed, this has a dramatic lurching behavior, as individual friction brakes are being pulsed.
[/b]

Well what you're saying seems to make technical sense, but I don't have the VSC either (my car is the base package with TRAC only) so I don't think that could be kicking in.

donee · 06-26-2007, 06:59 PM

Oops,

That will teach me to try to post at lunch time from work. I apparently did not review everything before I posted.

I read your other post, about lurching along from 50 feet, after posting my reply. And said - oh oh, I am probably wrong.

The issue then, is that in a tight turn, one of the tires lost normal force, and the torque of the motor snapped it out static friction. The Prius is tall, and does roll somewhat. That rolling action will reduce weight on the inside wheels. The electric motor does have a whole bunch of low-end torque.

There have been other Prius owners that have had VSC kick in during turning situations, and they say its like the car had a mind of its own, trying to steer them the wrong way.

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06-26-2007, 10:36 AM	#1
TooFolkGR Member Join Date: Jun 2007 Location: Grand Rapids, MI Posts: 34 My Car: 2007 Prius Package: Base Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I've got a New 2007 Prius with about 3,000 miles on it. The other day (Saturday) I was stopped at what we call a "Michigan U-Turn" here in Michigan. It's where you have to go past an intersection then do a U-turn to turn right at the intersection instead of making your usual left. Anyway it was a warm day, probably 91 degrees. I had the air conditioning running, but when I stopped at the Michigan U-Turn my engine shut off (which is pretty typical.) When the light turned green and I pressed on the accellerator, the car started lurching. Really lurching, not unilke a regular car does when it's running out of gas (yes, I have had that happen to me). Of course I had a full tank of gas and wasn't pressing down on the accellerator very hard. It lurched for about 50 feet, at which point one of the orange lights on the display started flashing. I -think- (though I'm not sure) it was the Traction control signal with the wavy lines behind the car. Any possible explanation for this? It hasn't happened since. The only reason I suspect the traction control is that in a couple other situations (where I went over bumps and one tire left the road for a split second) that light has flashed at me. I don't have any reason to believe I was going over a bump though, and the car lurched as never before. I am still under warranty; worth getting checked out?

06-26-2007, 11:27 AM	#2
qbee42 Senior Member Join Date: Mar 2006 Location: Northern Michigan Posts: 5,556 My Car: 2006 Prius Package: #7 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 5	If it was a yellow indicator, it was probably the traction control. Most likely it was doing what it does, which is keeping the wheels from spinning. There must have been something slippery or loose on the road surface. Tom

06-26-2007, 12:20 PM	#4
priussoris Join Date: Apr 2007 Posts: 1,005 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	The traction control is the only thing that I don't care for in the prius. We took a trip down to the Ozarks last weekend and had a lot of hilly gravel roads with pot holes and motorgrader grooves etc... it took a while to get up the hills had to go very slow, a little faster and 1 wheel spins and t/c takes over. But if that is what it takes to keep mg1 in good shape so be it.

06-26-2007, 01:14 PM	#5
donee Senior Member Join Date: Aug 2005 Location: Chicagoland Posts: 1,506 My Car: 2006 Prius Package: #2 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Hi All, Since I have never seen a wavy line car symbol, I bet that is the VSC symbol, not the TC symbol. And the action of your car tends to confirm that, in my opinion. My car only has the TC. Get the alignment checked, and I would add a BT Tech plate, or other rear-end stiffening/dampening device. One test is find some open asphalt, and try to pull too tight a turn at say 15 mph. The car should understeer and the tires slide, and scrub off speed. If the car tends to get a mind of its own, and kinda wiggles to the right, in a left hand turn, and not scrub off speed, its probably alignment or rear end flex. Talking a little out of my expertiece here, but give it a try. What I think happens in tight turns is the back end flexes, and steers the car in oposition to the front of the car. The VSC sensors detect this, and VSC kicks in to try to straighten out the manuever. Of course, your trying to turn. At slow speed, this has a dramatic lurching behavior, as individual friction brakes are being pulsed.

06-26-2007, 06:59 PM	#8
donee Senior Member Join Date: Aug 2005 Location: Chicagoland Posts: 1,506 My Car: 2006 Prius Package: #2 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Oops, That will teach me to try to post at lunch time from work. I apparently did not review everything before I posted. I read your other post, about lurching along from 50 feet, after posting my reply. And said - oh oh, I am probably wrong. The issue then, is that in a tight turn, one of the tires lost normal force, and the torque of the motor snapped it out static friction. The Prius is tall, and does roll somewhat. That rolling action will reduce weight on the inside wheels. The electric motor does have a whole bunch of low-end torque. There have been other Prius owners that have had VSC kick in during turning situations, and they say its like the car had a mind of its own, trying to steer them the wrong way.