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      02-12-2019, 10:49 AM   #1
Blue_e82
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E-diff question

If im correct the e-diff uses the abs sensors. If the sensors dont work and cant read any speed at all, does that mean the diff acts as an LSD?

My my car eats away sensors at the moment and they dont read any speed at all. When i jack the car up and spin one of the rear tires they both go in opposite directs like how it would with an open diff, but when i was on a dirt road i got on the gas a bit going in a straight line and both tires lost traction instead of 1. Id like to try it on an actual road but id like my tires to last as long as they can lol

Edit: asked a friend if he knew anything about how the e-diff works and he said it might turn into an LSD after a certain mph but wasnt sure

Last edited by Blue_e82; 02-12-2019 at 11:11 AM.
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      02-12-2019, 10:57 AM   #2
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Quote:
Originally Posted by Blue_e82 View Post
If im correct the e-diff uses the abs sensors, if the sensors dont work and cant read any speed at all, does that mean the diff acts as an LSD?

My my car eats away sensors at the moment and they dont read any speed at all. When i jack the car up and spin one of the rear tires they both go in opposite directs like how it would with an open diff, but when i was on a dirt road i got on the gas a bit going in a straight line and both tires lost traction instead of 1. Id like to try it on an actual road but id like my tires to last as long as they can lol
this sounds interesting
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      02-12-2019, 12:03 PM   #3
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Quote:
Originally Posted by Blue_e82 View Post
If the sensors dont work and cant read any speed at all, does that mean the diff acts as an LSD?
No.

Edit:

You sure you're not confusing the brake wear sensor with the wheel speed sensor? If your wheel speed sensors were messed up you'd be throwing codes left and right. ABS codes, DSC codes, DTC codes, and probably others.
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      02-12-2019, 12:15 PM   #4
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Quote:
Originally Posted by Suprgnat View Post
No.

Edit:

You sure you're not confusing the brake wear sensor with the wheel speed sensor? If your wheel speed sensors were messed up you'd be throwing codes left and right. ABS codes, DSC codes, DTC codes, and probably others.
Yeah im sure its the abs sensors. Have a few dsc codes, traction control and abs is off, speedo cuts off after a certain speed, seatbelt and airbag lights come on when the speedo goes out, etc..

I found some other forum posts about the e-diff and watch some videos and i think i know how it works now but still makes me wonder how it reads wheel speed to apply brakes and act like an LSD.
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      02-12-2019, 12:41 PM   #5
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Quote:
Originally Posted by Blue_e82 View Post
still makes me wonder how it reads wheel speed to apply brakes and act like an LSD.
Without working wheel speed sensors (and the computer), it's just an open diff. On the dirt road you just had equally bad traction on both wheels.

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Originally Posted by Blue_e82 View Post
speedo cuts off after a certain speed
LOL, "What's Behind Me, It's Not Important."

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      02-12-2019, 01:39 PM   #6
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Without the sensors active, it's just an open diff. On gravel, everything is slippery enough that it may have felt like you had both tires doing work for you, but an open diff can't 'turn into' an LSD.
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      02-12-2019, 01:51 PM   #7
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Quote:
Originally Posted by Soterios View Post
Without the sensors active, it's just an open diff. On gravel, everything is slippery enough that it may have felt like you had both tires doing work for you, but an open diff can't 'turn into' an LSD.
Ok makes sense. Now that i understand how it works without the sensors i feel like it was a stupid question. Idk how i didnt figure that put on my own
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      02-12-2019, 02:17 PM   #8
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Quote:
Originally Posted by Blue_e82 View Post
Ok makes sense. Now that i understand how it works without the sensors i feel like it was a stupid question. Idk how i didnt figure that put on my own
Nah. The e-diff thing is weird. Witchcraft, for sure. No stupid questions, here.
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      02-12-2019, 03:27 PM   #9
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Originally Posted by Soterios View Post
Nah. The e-diff thing is weird. Witchcraft, for sure. No stupid questions, here.
"Any sufficiently advanced technology is indistinguishable from magic." A.C. Clarke
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      02-12-2019, 07:39 PM   #10
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The e-diff works by applying the brake on the wheel which is spinning to cause the open diff to put more power to the wheel which is not - thus (poorly) emulating a LSD.

To do this job it needs to know the speed of each individual wheel; thus if it's got insane readings from one or both wheels it will not intervene and act as an open diff.

It's entirely possible to loose traction with both wheels on a dirt road with an open diff, since you have similar levels of grip on both wheels and overwhelming torque which will break both loose at the same time.
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      02-12-2019, 08:30 PM   #11
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I can confirm these cars are very capable of roasting both wheels AND roasting only 1

chris_flies mind posting the 1M DSC settings you used?
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      02-13-2019, 08:34 AM   #12
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I once briefly spun both rear tires on a friends gravel driveway. It was not hard at all. He didn't like it much, however.

I recently replaced brake pads and was surprised that the rears were worn as much as the fronts. Some of that had to be due to the ediff.
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      02-13-2019, 09:22 AM   #13
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I've wondered what the hell this e-diff was that gets mentioned on here. So it's really the traction control creating sort of a virtual LSD ?
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      02-13-2019, 09:32 AM   #14
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Quote:
Originally Posted by gjm120 View Post
I've wondered what the hell this e-diff was that gets mentioned on here. So it's really the traction control creating sort of a virtual LSD ?
Basically yes. The computer just applies braking to the wheel that's slipping to balance it out. It works...ok... you can leave two stripes on the road, but it's pretty pale in comparison to a true LSD.
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      02-18-2019, 10:46 AM   #15
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Quote:
Originally Posted by desertman123 View Post
I can confirm these cars are very capable of roasting both wheels AND roasting only 1

chris_flies mind posting the 1M DSC settings you used?
https://www.1addicts.com/forums/show...642&page=5

This is an entire thread of 135i (and some 128i) DSC settings being compared to 1M settings. The uebersteerung value was one of my favorites to change (sideways-ness ensued).

https://bmw135iblog.wordpress.com/20...track-nannies/

This is a blog post with all sorts of nannies that I, and anyone with the capability/blind determination to code removed.

I wouldn't mess with these until you get your DSC issues fixed, OP.
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