Traction Control

[wimpog]

How does the Traction Control work?
The dealer I went to said, if turned off, only one wheel would spin. He couldn't quite explain it in details. Thanks,

[DAVE PARKER]

Here is the easy non engineer jargon answer:
Traction control on the modern VW uses the wheel speed sensors, steering angle indicator, and a yaw sensor to determine orientation of the car, the direction of the car, wheel speed (to determine skids), and vehicle speed. The ABS/Traction control uses this information to process how to apply the individual wheel brakes (no driver input needed) to slow the car and gain more positive traction. There is also a tie in with the Engine management controls of the vehicle (mostly through the throttle control). There is no physical connection between the throttle pedal and the throttle valve, it is a "fly by wire" car. The engine management/ traction control work together to keep the car stable.

VW calls their program ESP (Electronic Stability Program) and it can be "turned off" through the button on the center console. However, it is imbedded in the car's electronics and can not really be defeated. The ESP "off" button just "dumb's it down" some. The program is pretty seamless and most of the time you will not ever feel it working. The exception to that statement is when you have the car in a low traction situation for the front wheels (think ice) and push the throttle to the floor. The ESP will not allow the engine to spool up or the wheels to spin.

There is nothing I have more fun with than a salesperson whom does not know the product that they are selling.

If you have more questions just ask.

cheers
dave parker

[wimpog]

Originally Posted by DAVE PARKER

Here is the easy non engineer jargon answer:
Traction control on the modern VW uses the wheel speed sensors, steering angle indicator, and a yaw sensor to determine orientation of the car, the direction of the car, wheel speed (to determine skids), and vehicle speed. The ABS/Traction control uses this information to process how to apply the individual wheel brakes (no driver input needed) to slow the car and gain more positive traction. There is also a tie in with the Engine management controls of the vehicle (mostly through the throttle control). There is no physical connection between the gas pedal and the throttle, it is a "fly by wire" car. The engine management/ traction control work together to keep the car stable.

If you have more questions just ask.

cheers
dave parker

Thank you Dave for the explanation.
What happens if you turn it off, and why would you? Is it true that when Traction Control is off, only one wheel is spinning?

[DAVE PARKER]

I updated my answer to include your second question.
cheers
dave parker

[Keithuk]

The Electronic Stabilisation Programme - ESP as Dave says just uses sensors to detect wheel slip and takes action to stop skidding and give you optimum traction. Sensors and applying the brakes to one or more wheels and reducing engine power if necessary. You can turn off the ESP but you'll see the annoying light flashing on the dash. This isn't true traction control.

The GTI\GTD have Electronic Stabilisation Programme (ESP) including Electronic Differential Lock (EDL) is not in fact a differential lock, Traction Control (ASR) and Countersteer Support but the GTI has XDS electronic differential lock.

[wimpog]

Originally Posted by DAVE PARKER

I updated my answer to include your second question.
cheers
dave parker

Thanks David.
Is there any way to block the differential, in case you get stuck in the snow?

[DAVE PARKER]

No. Although I have found that these cars do well in snow without any changes to the car. You just need to make the usual modifications to the driver that most Americans fail at, which is the following:
1. SLOW DOWN. I cant say or stress this enough.
2. Leave extra space and increase following distances.
3. Slow down.

Our JSW did great in the snow until the snow got to be about six inches deep, then the JSW started to struggle (which I expected). At that point it was time to crank up the Ford F250 with four wheel drive.
Or stay home.

cheers
dave parker

[speedracer1407]

Originally Posted by wimpog

How does the Traction Control work?
The dealer I went to said, if turned off, only one wheel would spin. He couldn't quite explain it in details. Thanks,

Let me take a shot at explaining the one-wheel-spinning thing, since it seems like the guy at the dealer didn't know what he was talking about.

All cars have differentials. They are the mechanical component that distributes the torque from the output shaft of the transmission to the 2 drive shafts (and therefore the wheels). All differentials in front and rear-wheel-drive cars are designed to let the two drive wheels spin at different speeds. This is because when you turn the car, say left, the left wheels will turn slower than the right wheels. As a result, in low-traction situations while accelerating, if one drive wheel loses traction first and begins spinning, it will spin on its own, and little or no torque will be distributed to the other wheel with more traction. This is true of all cars with the relatively rare exception of higher performance cars that sometimes have a "limited slip differential" that helps distribute power to both drive wheels more evenly.

It is not true, however, that in all low-traction situations, only one drive wheel will lose traction and spin during acceleration. If both wheels have equally limited traction, then both wheels will lose traction in a similar manner.

The VW, and pretty much every new car available today, has a traction management program that uses computers, accelerometers, and other sensors to prevent the loss of traction, or "skidding" in any circumstance, whether braking, accelerating, or turning. Of course, this does NOT increase traction, but merely prevents the loss of control associated with wheels that have lost traction. You can break out the 3 primary functions of this traction management program (that's not an official name or anything) as follows:

ABS: You're probably familiar with this. Uses sensors and computers to detect the lock-up and skidding of wheels when braking, and interrupts the hydraulic pressure in the brake system to release the brakes momentarily to help the wheels start turning again and regain traction.

Traction control: When 1 or more wheels looses traction while accelerating and begins to spin, the computer applies the brakes momentarily and cuts engine power to slow the spinning wheel down and stop it spinning.

Stability control: If you begin to slide sideways in a turn, the system will apply the brakes to individual wheels to try to "steer" the car toward where it thinks you're actually trying to go. If you're taking a hard left turn, and you begin to slide, the system may, for example, apply the brakes to the left hand wheels, thus helping "turn" the car more forcefully to the left.


My 2011 TDI has button that lets you turn off ONLY the traction control part of the program, allowing the wheels (or just one wheel in some circumstances) to spin freely in low traction situations. This is useful when you're really stuck and need a bit of wheel spin to rock the car or power through deep fluffy snow.

It's also worth noting that none of these systems are unique to VW. Pretty much every new car has it, and i'm pretty sure all are federally mandated standard features on all new cars beginning with the 2012 model year. They also work transparently, and very well. I do wish I could turn off the stability control sometimes, for a bit of slip-slidy fun in certain situations.