ASC and how one should use it !

[Nigel Worc's]

Hello chaps.

I had "an incident" on Friday, nothing dramatic thanks to the car, but I just wanted to run through ASC and what you're supposed to do if it activates, because I actually do not know.

ABS, is leave it alone to sort things out, but ASC ?

I went around a roundabout (I think it's called the catford interchange, where the A14 starts after you leave the M6), I exited in lane two onto the A14, and used moderate accelaration, as one does, with hgv's on my nearside.

I didn't spot anything other than a wet road surface, as it was raining , but my ASC activated, for about 15 seconds, I just loosened my grip on the wheel, and left things as they were, the car sorted it, and I carried on, if I hadn't had warning from my dashboard, I'd not have known anything was happening.

I can post the "incident" in video form if anyone is bored enough to want to see it.

it's just a "what is the correct procedure" question really.

[powerstroke]

Nigel Worc's said:

Hello chaps.

I had "an incident" on Friday, nothing dramatic thanks to the car, but I just wanted to run through ASC and what you're supposed to do if it activates, because I actually do not know.

ABS, is leave it alone to sort things out, but ASC ?

I went around a roundabout (I think it's called the catford interchange, where the A14 starts after you leave the M6), I exited in lane two onto the A14, and used moderate accelaration, as one does, with hgv's on my nearside.

I didn't spot anything other than a wet road surface, as it was raining , but my ASC activated, for about 15 seconds, I just loosened my grip on the wheel, and left things as they were, the car sorted it, and I carried on, if I hadn't had warning from my dashboard, I'd not have known anything was happening.

I can post the "incident" in video form if anyone is bored enough to want to see it.

it's just a "what is the correct procedure" question really.

Basicly its linked to the ABS and if it is operating it thinks you are pushing on a litle to hard or there was oil or mud on the road causing a loss of traction on one or more wheels !!! I supose the correct procedure would be to slow down and/or drive more smoothly or turn it off and trust you own judgement !!!

[Pints]

We're always bored here, Nigel. It's why we post on PH.

Get the video up.

[Nigel_O]

That particular section of road has been polished smooth by the large volumes of traffic, accelerating up to NSL from the very slow roundabout. In the damp, I can spin my wheels in the first four gears and in the wet, even 5th isn't safe. Next time, try the inside lane where the HGVs have been - it's even worse!

ASC is simply a reverse of ABS - it modulates the power reaching the wheels (by various methods) to reduce or prevent wheelspin. There's no reason why you shouldn't just keep your foot planted and let the electronics sort it out for you. In fact on some brake-assisted ASC, it's a good idea, as the diff will then transfer the power to the wheel with better grip (similar trick employed by off-roaders with open diffs - apply the brakes to regain drive - sounds weird but it works)

I have a much more sophisticated system in my car - it instantly knows when one or both driven wheels is spinning, it chooses whether the grip is gradually returning or gradually worsening and modulates the throttle opening accordingly. It chooses whether to back off completely to regain grip or whether to move off-line to find a better surface. Its the squishy blobby bit between the steering wheel and the driver's seat....

[vonhosen]

Nigel_O said:

I have a much more sophisticated system in my car - it instantly knows when one or both driven wheels is spinning, it chooses whether the grip is gradually returning or gradually worsening and modulates the throttle opening accordingly. It chooses whether to back off completely to regain grip or whether to move off-line to find a better surface. Its the squishy blobby bit between the steering wheel and the driver's seat....

But it can't brake individual wheels.

[GravelBen]

I've heard stories about people confusing stability control systems by correcting themselves at the same time, if true maybe its better to 'think dumb' and let it sort things out itself.

[Trif]

GravelBen said:

I've heard stories about people confusing stability control systems by correcting themselves at the same time, if true maybe its better to 'think dumb' and let it sort things out itself.

My understanding is that you are always want to keep the steering wheel pointing in the direction you want to go. You do not want to over correct as the computer will be trying its hardest to get you going in that direction.

My only experience of stability control is DSC in a Z4 on a car limits day with dreadful weather. Going round the cone far too fast and plenty of right foot (on purpose) it cut all the power and stabilised the car until grip had returned and let me accelerate away.

[Munter]

Nigel_O said:

I have a much more sophisticated system in my car - it instantly knows when one or both driven wheels is spinning,

No your system does not. Your system knows quite some time after. By the time a human can tell it's happening a TC/ASC system would already have delt with the problem

[vonhosen]

Trif said:

GravelBen said:

I've heard stories about people confusing stability control systems by correcting themselves at the same time, if true maybe its better to 'think dumb' and let it sort things out itself.

My understanding is that you are always want to keep the steering wheel pointing in the direction you want to go. You do not want to over correct as the computer will be trying its hardest to get you going in that direction.

My only experience of stability control is DSC in a Z4 on a car limits day with dreadful weather. Going round the cone far too fast and plenty of right foot (on purpose) it cut all the power and stabilised the car until grip had returned and let me accelerate away.

Yep.

It uses the ABS sensor on each wheel to detect differences at each wheel as well as a sensor on the steering wheel (looking at your intent) & a sensor looking at the amount of turn around the vertical axis (the actual yaw rate). It will then brake individual wheels &/or limit drive to wheels in order to try & keep you going where your steering tells it you want to go. That's DSC mind you, ASC is a less sophisticated earlier incantation.

[Nigel Worc's]

So, leave it alone then ..... it did seem ok.....I just wondered.

If you backed off, would/could doing that cause problems ?

It is a wonderful system, what would DSC do better ?

I thought DSC was just a dearer system that must have been specced when new, because, my mate has a 7 series, older than my 5 series, he's had it from new, and he has DSC, where mine has ASC.

I'll post the video ....as suggested...but you wont see a lot, in fact I'll be surprised if you can tell anything is wrong, because if the warning light hadn't of been flashing rapidly at me, I wouldn't have known anything was up.

To my namesake who suggested I switch it off and deal with it myself, why ?, it'll be far quicker and better at it than me ...... and BMW discourage you from doing this, by leaving a big yellow warning triangle illiminated if you do disable it.

[vonhosen]

Nigel Worc's said:

So, leave it alone then ..... it did seem ok.....I just wondered.

If you backed off, would/could doing that cause problems ?

It is a wonderful system, what would DSC do better ?

I thought DSC was just a dearer system that must have been specced when new, because, my mate has a 7 series, older than my 5 series, he's had it from new, and he has DSC, where mine has ASC.

I'll post the video ....as suggested...but you wont see a lot, in fact I'll be surprised if you can tell anything is wrong, because if the warning light hadn't of been flashing rapidly at me, I wouldn't have known anything was up.

To my namesake who suggested I switch it off and deal with it myself, why ?, it'll be far quicker and better at it than me ...... and BMW discourage you from doing this, by leaving a big yellow warning triangle illiminated if you do disable it.

I don't think that ASC has the steering & yaw rate sensors, it just looks to see if one or more of the driven wheels are loosing traction. If one is it applies brakes to that wheel & if both are it reduces power.

DSC however is the BMW version of ESP.

http://dl3.interlake.net/shared/wm/M225693_2007121...

Edited by vonhosen on Sunday 29th April 16:25

[ScoobyChris]

My understanding is ASC only has sensors which detect slip on the driven wheels and shift power/brake as needed. DSC has more sensors and I think works on all the wheels and with yaw sensors allows the car to go in the direction the front wheels are steered.

Some marketing bumpf:
http://www.bmw.com/com/en/insights/technology/tech...
http://www.bmw.com/com/en/insights/technology/tech...

Chris

[james_gt3rs]

Nigel Worc's said:

I didn't spot anything other than a wet road surface, as it was raining , but my ASC activated, for about 15 seconds, I just loosened my grip on the wheel, and left things as they were, the car sorted it, and I carried on, if I hadn't had warning from my dashboard, I'd not have known anything was happening.

That's quite a typo

[Vaux]

Nigel Worc's said:

To my namesake who suggested I switch it off and deal with it myself, why ?, it'll be far quicker and better at it than me ...... and BMW discourage you from doing this, by leaving a big yellow warning triangle illiminated if you do disable it.

Good plan - this is what can happen if you turn the TLAs off (or don't have any):
http://youtu.be/EOQpV1NmYgE (contains swearing)

[Nigel_O]

Nigel Worc's said:

To my namesake who suggested I switch it off and deal with it myself, why ?, it'll be far quicker and better at it than me ...... and BMW discourage you from doing this, by leaving a big yellow warning triangle illiminated if you do disable it.

Sorry - that wasn't my suggestion - I was simply saying that I don't have any kind of electronic aids, other than ABS, so I HAVE to manage traction myself, which I tend to do without too much drama.

However, I have a fair amount of power going through the front wheels - when they spin, its very easy to feel it happening and its even easier to handle it. If I had a decently powerful/torquey RWD AND it had ASC/DSC, I too would use it the vast majority of the time, as the consequences of getting it all wrong usually involve facing the wrong way.

[Nigel Worc's]

Video :

http://www.youtube.com/watch?v=3eZa10IVDlM&fea...

Like I said, without seeing the dash you can't tell it is active, it is active from the moment I begin to accelerate to pass the lorry, until I'm way past him.

I can't see what I'm slipping on either, nothing looks any different to me about the road surface.

[powerstroke]

Vaux said:

Nigel Worc's said:

To my namesake who suggested I switch it off and deal with it myself, why ?, it'll be far quicker and better at it than me ...... and BMW discourage you from doing this, by leaving a big yellow warning triangle illiminated if you do disable it.

Good plan - this is what can happen if you turn the TLAs off (or don't have any):
http://youtu.be/EOQpV1NmYgE (contains swearing)

Good plan if you are a crap driver like the prat in the vid to leave it on..

[powerstroke]

Nigel Worc's said:

Video :

http://www.youtube.com/watch?v=3eZa10IVDlM&fea...

Like I said, without seeing the dash you can't tell it is active, it is active from the moment I begin to accelerate to pass the lorry, until I'm way past him.

I can't see what I'm slipping on either, nothing looks any different to me about the road surface.

That junction is hidious!! pot holes funny cambers and slick tarmac with oil, that bit where you come down from the M6 its marked A14 on the RHL but ends before the bridge and then forces you to merge if you are stupid enough to take notice of the road markings and get in the right hand lane....the camber then the up hill exit from the roundabout at the start of the A14 combined with the press on driving style most likely made the ASC opperate

[Nigel Worc's]

powerstroke said:

That junction is hidious!! pot holes funny cambers and slick tarmac with oil, that bit where you come down from the M6 its marked A14 on the RHL but ends before the bridge and then forces you to merge if you are stupid enough to take notice of the road markings and get in the right hand lane....the camber then the up hill exit from the roundabout at the start of the A14 combined with the press on driving style most likely made the ASC opperate

I've used that junction thousands of times, never had an issue before, there must be some oil on the road surface, I'm not concerned about what caused it, I was looking for advice on what you are supposed to do when you have the ASC active for so long, normally if you activate it, it's a split second or so.

[kaf]

Logic says that if it's on for an extended length of time you are losing grip.

There are only 3 causes.

Too much gas/speed
Too much brakes
Too much steering

Seems in that case that logic is to identify and remove the cause.

At which point the system will no longer be needed.