For those interested in the relationship between Quattro, ESP, EDL, ASR and ABS, here is a brief ...
10-05-2003, 07:47 PM
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For those interested in the relationship between Quattro, ESP, EDL, ASR and ABS, here is a brief ...
Overview on how the systems work together.
First, Quattro is a mechanical system that uses a Torsen diff to bias the power transfer front to rear and vice versa. In normal driving condition it is said that the Torsen provides or distributes 50% of the power or traction to the front axle and 50% to the rear.
If there is wheel slippage, the Torsen will correct the situation by biasing the power to the wheels with more traction. It can vary the bias from approximately 64% front to 34% rear and vice versa.
Second, ESP is the electronic system that regulates and controls the EDL, ASR and it uses ABS inputs. All three systems are integrated in the ESP programming. In addition to the previously mentioned systems, the ESP control unit takes in additional data from other sensors that measure the rotational speed of the car about its vertical axis, lateral G force, brake pressure and steering angle. Furthermore ESP operates across the entire speed range in combination with ABS. If the ABS system fails, ESP will shut off and both warning lights will go on. When you deselect the ESP switch (off position), ESP is now out of the loop. The lateral G force sensor, the vertical axis sensor, ASR, steering angle and brake pressure sensors are not functioning. You are down to the basic Quattro and EDL. But note this EDL works only up to a speed of 50 mph (80kph). So with ESP switched off and your car going more then 50mph (80kph) you are basically left with Quattro only. So it is wrong to say that EDL is a function of Quattro, rather it is a function of ESP which is an electronic computer that control various other electronic components. BTW, I believe that on a Front Track A4 the EDL shuts off at a much lower speed.
Now from my own experience driving this car in the winter and testing it with ESP on or off this is what I can tell you happened. I'm not trying to lecture you or anybody else here, just giving out info for the people on this board that may never get the chance to see what this car can do in snowy conditions. It seems a lot of you live in generally warmer climates.
If you accelerate in a strait line on a snow covered/icy road with ESP on, the car will first launch forward, EDL will kick in and if EDL is not enough then ASR kicks in and the car basically dies right there on the spot, figure of speech of course.
Same conditions as above but ESP turned off. Again the car launches forward, EDL starts to kick in but is overwhelm by the fast acceleration and once you pass what is perceived a speed of 50 mph (80kph) it drops out leaving you with Quattro only and boy the fun starts. You can bring the car sideways, power slide it, and do four wheel drifts ECT...
Another test I did with the car was to accelerate with the wheels fully turned in one direction as if you were at a stop sign and you wanted to turn at a 90 degree intersection. With the ESP on, the car again wants to launch forward, the EDL immediately kicks in sensing the power demand continuing to increase, the ESP starts activating the ASR, basically shutting down the power immediately. This is quite dramatic and extremely efficient because the car make and incredible slow and controlled turn.
Same scenario but ESP off. Again the car launches forward, EDL tries to hold it back but is overwhelm by the fast rotational speed of the wheels and drops off line. Now you are in for a ride, the car goes completely in to a four wheel drift and into a 360 degree donut and will spin for ever in this 360 manoeuvre, well almost. Like the big boys in rally, power on donuts.
Lastly I did a test on a snow covered 3 lane highway (nobody around). With the ESP on, I was cruising at give or take a few mph around 60 (100kph) and all I did was give left to right steering wheel inputs as if to break the cars tail end loose, well I can tell you the ASR kick in nicely just cutting off the power until the wheel were straiten, this demonstrated the steering angle sensor and the rotational vertical axis sensor working in conjunction with ESP. Note because of the speed EDL never kick in.
I did the same test with the ESP switched off and nothing happened.
Still to be resolved at this time is a way to disconnect EDL without disabling ABS. Also I'm researching more deeply into the ESP. There is a possibility that ESP might still be on even with the switch deselected to the off position and the warning light illuminated. It appears that it could be in a "passive mode" and once a certain limit is reached or exceeded, it might step in to try to alleviate the problem. So far I have seen nothing official from Audi on this matter, not in the owner's manual and I even have a friend who works for Audi as a technician who says that when deselected to off the ESP is off.
Mike
First, Quattro is a mechanical system that uses a Torsen diff to bias the power transfer front to rear and vice versa. In normal driving condition it is said that the Torsen provides or distributes 50% of the power or traction to the front axle and 50% to the rear.
If there is wheel slippage, the Torsen will correct the situation by biasing the power to the wheels with more traction. It can vary the bias from approximately 64% front to 34% rear and vice versa.
Second, ESP is the electronic system that regulates and controls the EDL, ASR and it uses ABS inputs. All three systems are integrated in the ESP programming. In addition to the previously mentioned systems, the ESP control unit takes in additional data from other sensors that measure the rotational speed of the car about its vertical axis, lateral G force, brake pressure and steering angle. Furthermore ESP operates across the entire speed range in combination with ABS. If the ABS system fails, ESP will shut off and both warning lights will go on. When you deselect the ESP switch (off position), ESP is now out of the loop. The lateral G force sensor, the vertical axis sensor, ASR, steering angle and brake pressure sensors are not functioning. You are down to the basic Quattro and EDL. But note this EDL works only up to a speed of 50 mph (80kph). So with ESP switched off and your car going more then 50mph (80kph) you are basically left with Quattro only. So it is wrong to say that EDL is a function of Quattro, rather it is a function of ESP which is an electronic computer that control various other electronic components. BTW, I believe that on a Front Track A4 the EDL shuts off at a much lower speed.
Now from my own experience driving this car in the winter and testing it with ESP on or off this is what I can tell you happened. I'm not trying to lecture you or anybody else here, just giving out info for the people on this board that may never get the chance to see what this car can do in snowy conditions. It seems a lot of you live in generally warmer climates.
If you accelerate in a strait line on a snow covered/icy road with ESP on, the car will first launch forward, EDL will kick in and if EDL is not enough then ASR kicks in and the car basically dies right there on the spot, figure of speech of course.
Same conditions as above but ESP turned off. Again the car launches forward, EDL starts to kick in but is overwhelm by the fast acceleration and once you pass what is perceived a speed of 50 mph (80kph) it drops out leaving you with Quattro only and boy the fun starts. You can bring the car sideways, power slide it, and do four wheel drifts ECT...
Another test I did with the car was to accelerate with the wheels fully turned in one direction as if you were at a stop sign and you wanted to turn at a 90 degree intersection. With the ESP on, the car again wants to launch forward, the EDL immediately kicks in sensing the power demand continuing to increase, the ESP starts activating the ASR, basically shutting down the power immediately. This is quite dramatic and extremely efficient because the car make and incredible slow and controlled turn.
Same scenario but ESP off. Again the car launches forward, EDL tries to hold it back but is overwhelm by the fast rotational speed of the wheels and drops off line. Now you are in for a ride, the car goes completely in to a four wheel drift and into a 360 degree donut and will spin for ever in this 360 manoeuvre, well almost. Like the big boys in rally, power on donuts.
Lastly I did a test on a snow covered 3 lane highway (nobody around). With the ESP on, I was cruising at give or take a few mph around 60 (100kph) and all I did was give left to right steering wheel inputs as if to break the cars tail end loose, well I can tell you the ASR kick in nicely just cutting off the power until the wheel were straiten, this demonstrated the steering angle sensor and the rotational vertical axis sensor working in conjunction with ESP. Note because of the speed EDL never kick in.
I did the same test with the ESP switched off and nothing happened.
Still to be resolved at this time is a way to disconnect EDL without disabling ABS. Also I'm researching more deeply into the ESP. There is a possibility that ESP might still be on even with the switch deselected to the off position and the warning light illuminated. It appears that it could be in a "passive mode" and once a certain limit is reached or exceeded, it might step in to try to alleviate the problem. So far I have seen nothing official from Audi on this matter, not in the owner's manual and I even have a friend who works for Audi as a technician who says that when deselected to off the ESP is off.
Mike
10-06-2003, 03:44 AM
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Maybe not. Some of the earlier A4s did not come with ESP, check your owner's manual. In my case....
ESP is actually a pita and I'm trying to bypass it.
10-06-2003, 06:43 AM
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ESP became an option on the '01 A4 (last year for the B5 chassis), so yours doesn't have ESP....
However, if you have quattro, then you should have EDL and ABS. Not sure about ASR though, there's a dash warning light on front drive A4's when it is activated, but there isn't one on quattro equipped cars.
All B6 chassis ('02+) cars have ESP as standard, along with all other electronic gadgets.
I too read something about you can't turn ESP completely off. But then I suspect you'd have to do something really stupid to activate ESP that way, in that case, it's probably a good idea to have it take control and safe you butt! ;-)
All B6 chassis ('02+) cars have ESP as standard, along with all other electronic gadgets.
I too read something about you can't turn ESP completely off. But then I suspect you'd have to do something really stupid to activate ESP that way, in that case, it's probably a good idea to have it take control and safe you butt! ;-)
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