Bora 4mo ESP kicking in at slow speeds

[grtuned]

Also fuse is definatley 5amp for haldex located at number 31 in fuse boxQUOTE=grtuned;702651]This is some data i've found regarding operation of the sensor which i think could be causing these issues[/QUOTE]

[kapowww]

This is some data i've found regarding operation of the sensor which i think could be causing these issues

And in English? lol

Is it saying it's a natural thing under certain conditions, or only if it's faulty?

In my car it feels as if just one rear wheel is dragging, not both the rear wheels. That's why I think it's the rear diff. Feels as if the clutch/spring packs are screwed and when going slow it doesn't have enough torque to over power the clutch in the diff to make it spin the same speed. Maybe I need to look from outside the car because I noticed when my wife dropped me off and turned tight it left skid marks (the rubber kind) but don't know which wheel(s) left them.

Also in regards to me removing fuse 31 to disable the haldex: I asked earlier.. If the fuse is removed then it is only FWD and takes the haldex AND rear diff out of the question?

[popeclement]

Hi jpflorez - in ref to your comment above, there is no clutch in the diff - the haldex coupling is an integral system ahead of the diff.

I know you have said you have had the system refilled with new oil and filter but it may be some components not working such as the electric pump/regulating valve. I think mechanically unless the car has been thrashed it is unlikely to be a diff issue. There are so many inputs into the Haldex controller from speed, accel & yaw sensors, it really requires someone with a good understanding of the codes to figure this out.

I don't believe there are any dealers even though they have the equipment, with enough master techs & familiarity on the system.

Maybe an Audi specialist may have the necessary experience?

[wai]

When I do a u-turn in my Bora 4mo at slow speeds I see the ESP light flash on and off and feel it braking a bit and it gets a bit jolty. I've only had this car for a very short time but since I believe it's similar to my old Audi A4 B6 1.8TQ surely it shouldn't be doing this?

What do you mean by "low speeds"? ESP should only kick in if the parameters of wheel speed, road speed, steering input, accelerator input, etc., all tell it to activate. Get it checked out, and also try and see if there is something else that is causing it to kick in.

[kapowww]

Hi jpflorez - in ref to your comment above, there is no clutch in the diff - the haldex coupling is an integral system ahead of the diff.

I don't believe there are any dealers even though they have the equipment, with enough master techs & familiarity on the system.

Maybe an Audi specialist may have the necessary experience?

Well the car's been checked by 3 mechanics at this stage. One a VW dealer and one is the best Audi/VW mechanic here in Melbourne (according to most on ozaudi.com and I've been seeing him for years). None can get a good answer. He says it's the clutch in the rear diff, not a problem with the haldex. Can you explain what you mean by no clutch in the diff?

What do you mean by "low speeds"? ESP should only kick in if the parameters of wheel speed, road speed, steering input, accelerator input, etc., all tell it to activate. Get it checked out, and also try and see if there is something else that is causing it to kick in.

We've figure out it shouldn't be a problem with the ESP but the ESP light flashes when this problem happens. Too bad the title of this thread is a bit misleading..

[djorkboy]

Here is my understanding of the setup of a Bora 4motion, feel free to correct where I am wrong (I'm used to it, I am married)....

It seems that a lot of people, including mechanics, use the word 'diff" when talking about the Haldex. I think this is partially because the Haldex is bolted to the diff housing.

The Haldex is a Viscous Coupling and contains clutches, but it is a totally separate unit from the Transaxle/Diff that the Haldex is merely bolted to. The diff contains no clutches, it is just a regular diff similar in concept to what you would find in any Commodore, Falcon etc.

In theory you could unbolt the Haldex, install a longer driveshaft connected directly to the transaxle and have a permanant 4 wheel drive system (well, it would be permanant until you drive it around a few corners and the transfer case blows up)

Here's a picture I knocked up in photoshop from a layout of an Audi TT..... (please don't think I'm trying to insult anyone's intelligence here, I know that everybody knows at least 90% of what this picture shows, if not more, I'm just trying to clarify my thoughts)

[djorkboy]

Now, having posted my previous tome, let me move onto my thoughts on this problem, and please bear in mind that I am an idiot and am usually completely wrong (as before, just ask my wife)

If it was the diff, which is purely mechanical, would there not be lots of crunching, grinding and whining if it had a problem bad enough to make the wheel skip?

If it was the Haldex would there not be an error code or light seeing as how the Haldex is so tightly monitored and controlled by the car's computer systems?

So that leaves the ABS. This to me seems most likely. The ABS can lock a wheel completely independently of the other systems. So if it were me I would be looking at the condition of my ABS sensors.

...oh, and I tried to replicate the problem a couple of times with my Bora and could not get it to happen. No matter how tight I turn or what speed I do it at I cannot get the wheels to skip, drag or chirp at all.

[popeclement]

Thanks djorkboy - your explanation v good. I started thinking ABS sensors but as the problem on my vehicle has only just started and can be reproduced doing either a RH or LH full lock turn, why would both sensors fail together - maybe its another common input to the Haldex?

[grtuned]

My understanding of the paragraph is at low speeds like taking of while turning the wheel speed sensors are not accurate so the
longtitudinal sensor compensates for speed input. Which if means if no signal is being transmitted to the abs unit from the wheel sensorsthe longtitudinal sensor may be causing ESP light to flash due to it being faulty. The only way to test would be to change it and see whathappens. like i said earlier post its an expensive test

And in English? lol

Is it saying it's a natural thing under certain conditions, or only if it's faulty?

In my car it feels as if just one rear wheel is dragging, not both the rear wheels. That's why I think it's the rear diff. Feels as if the clutch/spring packs are screwed and when going slow it doesn't have enough torque to over power the clutch in the diff to make it spin the same speed. Maybe I need to look from outside the car because I noticed when my wife dropped me off and turned tight it left skid marks (the rubber kind) but don't know which wheel(s) left them.

Also in regards to me removing fuse 31 to disable the haldex: I asked earlier.. If the fuse is removed then it is only FWD and takes the haldex AND rear diff out of the question?

[djorkboy]

My understanding of the paragraph is at low speeds like taking of while turning the wheel speed sensors are not accurate so the
longtitudinal sensor compensates for speed input. Which if means if no signal is being transmitted to the abs unit from the wheel sensorsthe longtitudinal sensor may be causing ESP light to flash due to it being faulty. The only way to test would be to change it and see whathappens. like i said earlier post its an expensive test

The VW Self Study document that covers the Haldex system says the following about the failure of the longitudinal acceleration sensor...

Without the additional measurement of longitudinal accelleration, it is not possible to determine the true vehicle road speed exactly in unfavourable conditions. The ESP and TCS functions fail. When ESP is activated, the Haldex coupling is opened.

This is a little ambiguous but, it might mean that in "unfavourable conditions" a failed longitudinal sensor could cause an ESP failure. But could this in turn cause the ABS system to get confused and lock a wheel? Is turning a really tight slow corner unfavourable enough for a failed longitudinal sensor to freak out.

Failure of a wheel speed sensor results in "No ABS control" and "No four-wheel-drive control" with the note that "The failure of a wheel sensor does not cause any restrictions to four-wheel drive" which sounds a bit like a contradiction to me. If four-wheel-drive control is lost does that mean the car can still operate in four-wheel-drive but just can't control it? That just doesn't sound right.

The more I read about this the more I agree with grtuned that it is a failed or faulty sensor that is causing the ESP or ABS to lock the wheel.