EDL Ice problem (it may be there)
02-02-2000, 06:59 AM
#42
Guest
Posts: n/a
Yes, all this speculative analysis really bothers me.
This is seeming more and more like the Salem witch trials, and I find the preponderance of speculation and the apparent lack of true technical knowledge and data disturbing, especially given the far reaching conclusions that are being drawn here.
02-02-2000, 07:27 AM
#43
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Introductions...
Hello everyone,
My name is Bob and I was asked by mm to join the conversation and possibly offer some help regarding our AWD system. If you have a question and would like to discuss it, please feel free to ask it.
Also, here is my bio. I'm an engineer for almost 20 years, not automotive. I've been building, fixing, driving (w/some minor racing) Audis since 1980, as a hobby. I've owned countless quattros over the years in many stages of completion. I've owned and worked on other cars too, incl. BMW, MB, Lotus, Alfa, Rover, Hondas, Toyotas. I have a friend who is an Audi mechanic for 10 years, and I know an Audi insider, who I've ask to help us to solve some common Audi problems. Hope I can help.
Regards,
Bob
96 A4QM
86 4KCSQM
My name is Bob and I was asked by mm to join the conversation and possibly offer some help regarding our AWD system. If you have a question and would like to discuss it, please feel free to ask it.
Also, here is my bio. I'm an engineer for almost 20 years, not automotive. I've been building, fixing, driving (w/some minor racing) Audis since 1980, as a hobby. I've owned countless quattros over the years in many stages of completion. I've owned and worked on other cars too, incl. BMW, MB, Lotus, Alfa, Rover, Hondas, Toyotas. I have a friend who is an Audi mechanic for 10 years, and I know an Audi insider, who I've ask to help us to solve some common Audi problems. Hope I can help.
Regards,
Bob
96 A4QM
86 4KCSQM
02-02-2000, 07:45 AM
#44
Guest
Posts: n/a
What we are basically talking about is a situation Jim de Arras experienced...
...in his S4 (below is a link to his description of what happened). There has been a lot of speculation here that his experience may have been related to some form of misbehavior or design flaw in the EDL system in his car.
The concern is that under certain conditions, EDL may be misled into braking a wheel when it should not and that this could lead to a loss or control and/or a spin. The posts in this thread and the prior on where Jim describes his experience should give you a feel for the scenarios and explanations that are being proposed.
I'm not sure to what extent this thread is still actively being discussed, as much of it is from yesterday, but I would still appreciate your thoughts for posterity if nothing else.<ul><li><a href="https://www.audiworld.com/forum/m/s4/34464.phtml">https://www.audiworld.com/forum/m/s4/34464.phtml</a</li></ul>
The concern is that under certain conditions, EDL may be misled into braking a wheel when it should not and that this could lead to a loss or control and/or a spin. The posts in this thread and the prior on where Jim describes his experience should give you a feel for the scenarios and explanations that are being proposed.
I'm not sure to what extent this thread is still actively being discussed, as much of it is from yesterday, but I would still appreciate your thoughts for posterity if nothing else.<ul><li><a href="https://www.audiworld.com/forum/m/s4/34464.phtml">https://www.audiworld.com/forum/m/s4/34464.phtml</a</li></ul>
02-02-2000, 08:02 AM
#45
Guest
Posts: n/a
There is always quaiffe...
You can get a quaiffe for the rear. That should reduce the differential causing the edl to kick in, but unplugging the abs is the only way to eliminate edl so far (maybe possible to reprogram).
You must be *really* flying to get the edl to kick in at speed. At the most I get a slight clunk when edl cuts in, never a bang. What kind of noise are you getting ice?
You must be *really* flying to get the edl to kick in at speed. At the most I get a slight clunk when edl cuts in, never a bang. What kind of noise are you getting ice?
02-02-2000, 08:07 AM
#46
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Posts: n/a
Re: Introductions...
Great,
Since I started this discussion, I'll give you mine. I am also an engineer, but since there is more money fixing networks than fixing cars, networks were my source of income. I have done all my own auto repairs for 25 years, and two dealerships have offered me a jobs after I have fixed problems they could not. I have 1 million accident free miles under my belt with no tickets. I also am an avid off-roader, and depend on understanding how my vehicle works. I have spent lot of miles on ice, mud, and off camber situations.
The whole jest of this boils down to the question, Will EDL engage when you are using engine braking to slow the vehicle down on low friction, split MU surfaces. If it does there is a potental stability issue, as edl will be braking the wheel providing directional stability in a De-acceleration situation.
Take care
Russ
(pull the fuse) grin
Since I started this discussion, I'll give you mine. I am also an engineer, but since there is more money fixing networks than fixing cars, networks were my source of income. I have done all my own auto repairs for 25 years, and two dealerships have offered me a jobs after I have fixed problems they could not. I have 1 million accident free miles under my belt with no tickets. I also am an avid off-roader, and depend on understanding how my vehicle works. I have spent lot of miles on ice, mud, and off camber situations.
The whole jest of this boils down to the question, Will EDL engage when you are using engine braking to slow the vehicle down on low friction, split MU surfaces. If it does there is a potental stability issue, as edl will be braking the wheel providing directional stability in a De-acceleration situation.
Take care
Russ
(pull the fuse) grin
02-02-2000, 09:45 AM
#48
Guest
Posts: n/a
Re: Introductions...
Hi Russ,
Typically, EDL _should_ not engage in these conditions that you describe. I am basing my response on traction control system design specifications that I have been privy to in the past, as well as my experience and the experience of others with Quattro IV EDL and other TC systems. I am not saying that this situation did not occur to you. There are many outside influences at work here. But this situation you describe has been addressed with modern TC systems. As you probably know, EDL is a 2-wheel TC program (times 2) added to the Bosch ABS system. It is an off-the-shelf Bosch "add-on" with many hours of testing. Audi did this for many reasons, including cost, and liabiity issues. As we all know, Quattro IV does not have stability control as of yet. Quattro can't correct stability or yaw problems. So it is easy to get into a bad situation even though traction and traction control is superb. No flames intended here, but I have driven BMW's stability control system and Quattro IV on the same stretch of road, and under certain conditions, the car with the stability control performed "better". Again, an argument can be made here.
Also, mm posted one of my responses below that relates to your discussions. Please take a look at it (but ignore the grammatical errors ;-)
Regards,
Bob
96 A4QM
86 4KCSQM
Typically, EDL _should_ not engage in these conditions that you describe. I am basing my response on traction control system design specifications that I have been privy to in the past, as well as my experience and the experience of others with Quattro IV EDL and other TC systems. I am not saying that this situation did not occur to you. There are many outside influences at work here. But this situation you describe has been addressed with modern TC systems. As you probably know, EDL is a 2-wheel TC program (times 2) added to the Bosch ABS system. It is an off-the-shelf Bosch "add-on" with many hours of testing. Audi did this for many reasons, including cost, and liabiity issues. As we all know, Quattro IV does not have stability control as of yet. Quattro can't correct stability or yaw problems. So it is easy to get into a bad situation even though traction and traction control is superb. No flames intended here, but I have driven BMW's stability control system and Quattro IV on the same stretch of road, and under certain conditions, the car with the stability control performed "better". Again, an argument can be made here.
Also, mm posted one of my responses below that relates to your discussions. Please take a look at it (but ignore the grammatical errors ;-)
Regards,
Bob
96 A4QM
86 4KCSQM
02-02-2000, 10:12 AM
#50
Guest
Posts: n/a
Re: Hmmm
I probably shouldn't have played the EDL/ABS card in my post above. The basic point was that engine braking *alone* can put a car out of control under the right conditions. Since I have experienced exactly this in a car with no EDL/ABS (but with the same Bridgestone tires -- different size), I think the episode under discussion may have been caused by this alone.