Traction Control Question

[Dave99GT]

Does the traction control system on the 03's measure wheel speed at all four wheels?
I ask because I have my brand new 315/35/17 GSD3's off today (I picked up a screw at the edge of the tread on one of them - I have to replace a tire now after only 100 miles ARGGGGHHH!).
In order to still use the car and get to work today, I threw my snow tires on the rear (235/45/17), but kept my summer tires on the front (275/40/17). When I was driving to work, I had forgotten to turn off the traction control, and when I hit 60 mph on the expressway, all of a sudden the car started to bog and sure enough, a look at the dash told me that the t/c had kicked in. So I quickly pushed the button to turn off traction control and no more problem.
I am assuming that the t/c system must somehow be able to tell the difference in size between the rear tires and front tires, but it did not register as a difference in rotational speed large enough to engage the t/c until I hit highway speed. The difference in diameter on my tires is only .29 inches (25.66" diameter on the 275's compared to 25.37" diameter on the 235's). My guess is that the t/c system measures speed at all four wheels. This is a surprise to me if it is true.
If this is true, then anyone running different size tires on the rear may want to always disengage t/c if you are going to hit the highway...
For example the difference in size between a 285/40/17 on the rear versus a stock 275/40/17 on the front (.32") could be enough to kick in the t/c on the highway, like mine kicked in this morning. The diameter of the 315/35/17 is almost identical to the 275/40/17 (only .02" difference), so that combination should not cause a problem with the t/c inadvertently left on...

 

[bcwang]

I would think it has to measure the speed difference of all 4 wheels, otherwise the traction control would be ineffective if both rear wheels spin on water or ice at the same rate.

 

[FireRed04Vert]

It absolutely reads all four wheels.

 

[silvercoffin]

huh?

Really? I didnt think our traction control was that sophisticated. It doesn't do anything except cut off the power when the back tire spins. I have slid my car across the road before and it didnt activate the TC. I have my traction control disabled with my latest tune..since I never take the car out in the rain or snow anyway so im no expert

 

[PowerWheels]

The only time I would think TC on this car would be any good would be on a trip in the rain. Just in case you have cruise control on and hit some freak oil patch in the road. Otherwise I think it's worthless, and dangerous where entering traffic.

 

[Huachipato]

TC works in conjunction with the ABS system. The ABS is reading the rate of all 4 wheels, and TC looks for one to be spinning much more than the other. Essentially, ABS is limited to when only the brakes are bing applied, and TC takes is one step further and works anytime the engine is running (if it is not turned off manually or by tune). Also, not only does it progressively bog the engine by altering the timing (depending on how much slipping is going on) but it may also apply the brake to the slipping wheel as well.

I am guessing mine is a freak system, as it does allow me to spin the tires in a launch without noticibly bogging the engine down. I know this is not the norm, but I can tell you that I have heard my tires squeeling all the way across an intersection with TC on and not felt the car bog at all even though the TC light comes on. In other situations, I have felt the car bog as most describe happens to them all the time.

 

[bunny_power]

TC works in conjunction with the ABS system. The ABS is reading the rate of all 4 wheels, and TC looks for one to be spinning much more than the other. Essentially, ABS is limited to when only the brakes are bing applied, and TC takes is one step further and works anytime the engine is running (if it is not turned off manually or by tune). Also, not only does it progressively bog the engine by altering the timing (depending on how much slipping is going on) but it may also apply the brake to the slipping wheel as well.

I am guessing mine is a freak system, as it does allow me to spin the tires in a launch without noticibly bogging the engine down. I know this is not the norm, but I can tell you that I have heard my tires squeeling all the way across an intersection with TC on and not felt the car bog at all even though the TC light comes on. In other situations, I have felt the car bog as most describe happens to them all the time.

Mine will let me spin the tires too, its just a matter of how aggressively you apply the gas, too much spin and it activates, just right and you can spin all the way through first.

And yeah, like everybody said, the system measures at all 4 wheels. I just had a front wheel speed sensor go bad and it shut down the ABS and the traction control systems.

 

[WraithCobra]

There is a sensor on the steering column that detects the position of the steering wheel. Ford TC uses a "Power Start" feature that allows a percentage of slip when the steering wheel is straight. Once the wheel is turned to a certain point the system goes into a more aggressive program to stop wheel slip. The system is an "All Speed" traction control system that pulls timing to lower engine output. If that isn't enough it skips fuel injectors, and finally uses the rear brakes (only at lower speeds) to stop wheel spin. It's not a bad system, it works fine in the GT and Mach's, but in our Cobra's the timing can only be pulled back so far before the supercharger bypass has to be opened and injectors get skipped.

 

[FireRed04Vert]

My understanding is the 05 is much more sophisticated and works much much better. The Stability control on my son's Lincoln LS8 is unbelievable and I've heard they are using a version of that.

Silvercoffin...the reason it reads the front sensors is to have something to compare the rears to.