Matt230K

There has been lots of talk in the past about how much ESP does after you turn it off. It doesn't cut throttle, but it still applies brakes. Well anyway, today at work, a mechanic had to check an E320 4matic for a wheel bearing noise to see what wheel it was coming from. So he put it up on the lift and I got in and drove the wheels so he could hear the sound.

I had ESP off and even though the throttle was not cutting out, you could feel the brakes pulsing, even through the gas pedal, because the brakes were still interrupting the power delivery trying to stop the wheels. Once it gets going, you don't notice it anymore. You could also see the difference in power delivery to the different wheels with 4matic. At idle, the rear wheels would start spinning and the fronts would hardly move. And as you accelerate, the rears were still moving faster than the fronts.

It would be interesting to try this with a C-class so you can feel the difference between ESP off and dyno mode. It's usually hard to feel the brakes working when you are on the road, but you can hear them sometimes.

Well, just thought I would share this observation.

avlis

This is no secret. It's been known that when ESP is off, there is a program running that brakes a spinning drive wheel to simulate a limited slip differential (STFF for more of Lynn's insight).

Dyno mode turns off this program. When you get throttle-happy in dyno mode, one drive wheel breaks loose and just keeps going until it gains traction on it's own. You end up doing a one-wheel burn out. I doubt this provides better acceleration times then when NOT in dyno-mode. If it did, why would they bother to include it?

AFAIK, most AWD systems do not provide a 50/50 torque split unless it's called for in a low traction situation.

Matt230K

Yeah, I already knew all this stuff and other here probably do also. I just thought it was neat to see it in action. It was kinda hard to get the wheels spinning at first because the brakes were trying pretty hard to stop them. I was trying to be gentle and rev up smoothly and the brakes put up a good fight for a while. But once I got the wheels spinning, I couldn't feel the brakes anymore. I don't know if maybe they give up eventually or what? Maybe just harder to feel.

Another interesting thing I noticed, when I was first doing this, the wheels were about an inch off the ground and the speedo was reading about 35mph at 3000 rpm. Then he put the car all the way up on the lift to get underneath it. I did the same thing and this time the speedo read 10mph at 3000 rpm. I don't know why it didn't shift gears when it was higher up in the air.

MarkL

I think in the past we've said that there are actually two systems, ESP (stability control) and "regular" traction control. Turning ESP off leaves the traction control component active. Traction control simply brakes a spinning drive wheel. ESP brakes the appropriate wheel(s) to stop unwanted vehicle spin (yaw).

MB-BOB

Matt, thanks for sharing this observation. I did not know about this and I'm guessing others are intrigued by the information as well.

ArPoe

So does turning the ESP off makes the car accrelates faster???
and will it damage the car???

Matt230K

Turning off ESP will stop the car from cutting the throttle every time the wheels slip. So if your wheels start to spin and you are on the gas, you will only spin them faster or go sideways. This will make you go slower in these situations.

In dry situations, if you know how to drive, ESP off can make you a bit faster. You might get a bit of wheelspin on the dry, especially when you shift if you are driving hard. But it won't cut the throttle at all. That hurts your momentum. So you can make it go slightly faster.

It won't damage your car, unless you slide into something.

Drew_ML

What probably happened was that when you first accelerated, there were speed differentials between the different wheels. Once 4ETS equalised that, it simply turned off. When 4ETS is active, you will be able to see the triangle blink, even with ESP off. In real world conditions, it really only activates in the first few seconds when starting off from a dead stop. After that it is mostly ESP that activates to control any understeer or oversteer.

The system - ESP/ASR/ABS/4ETS - is actually better integrated (even less noticable) on the C-class 4-matic since it's a newer version compared to the E-class's 4-matic/ESP initegration.