Sudden snap oversteer - no warning

[Voltigeur]

Originally Posted by Ateam

See that is the part I am wondering, how does mdm make it a more "lively" car. It does not effect, throttle, engine, braking, suspension or anything other than letting more yaw changes without intervening. Just curious how this brings more fun? (honestly am asking you and curiosu

Bit mystified but in my experience the car - not just MDM mind - as per my 1st post - when set up w/ throttle/steering/MDM is more responsive. Oh, I see your point: yes, MDM is just DSC-light, I was using it as shorthand for the other settings.

To your specific question: the car feels lighter on its feet and more precise; in some respects I regard it as a safer setting than all-nanny mode. In any case, on this day I did not in any way 'push' hard where the oversteer + correction in MDM was engaged. Frankly, not how I want to commute and as I got closer to the city I normally disengage it.

[Voltigeur]

Originally Posted by El_Duderino

+1
I apologize if I have misinterpreted the OP's previous posts, but your summer tires will NOT grip at 40F, regardless of how many miles you've driven on them prior to the oversteer incident occurring. This is a property of the rubber used in summer performance tires and no amount of warming up the tires will change their tendency to lose traction in cooler weather.

OK. I've driven my car 28k - and during winter in colder temps - without this reaction. BUT, not disputing the analysis: indeed, just the colour I was looking for. No worries.

Now I'm going to go back and research some good 4-seasons.

[Ateam]

Sorry if you meant MDM as in "m settings" than of course the car is more fun to drive with the throttle tweaked, gearbox shifts tweaked and steering tighter" Sorry for the confusion-I was using it in terms of dsc-light!

[DivideBYZero]

I've had this happen with MDM on. I was provoking the rear end while turning right, back stepped out, caught it with too much correction, got into a tank slapper, but caught it after going left, right, left. I too thought there was something wrong, but now I'm pretty much at ease with the idea that the e92 lets go more suddenly than my E46 M3 ever did. I guess that's the price you pay for such amazing turn in.

My tyres are Goodyear Eagle F1 Asymetric, temp was cool, maybe 8c, tyres were probably still cold as only 5 minutes into my drive.

Another thing to bear in mind is that MDM doesn't really help on the ROAD. It's a track mode, and it clearly states in the manual that you are likely to have an accident with this mode on as it allows large amounts of latteral slip.

My M button it set to Sport+, Steering to max and regular DSC. At this time of year with cold damp roads and diesel spills I could do without playing Drift Hero in heavy traffic!

[gthal]

Originally Posted by Ateam

You seem to lack basic reasoning and common sense.

Boy... you are a character for sure. I love internet tough guys

Something like this could happen to any of us. The point of the OP raising the issue here was that it was outside of the norm for the car to react this way. He wasn't being "irresponsible" or racing which is why it caught him off guard. Even with MDM on, the car shouldn't step out like this absent a failure of the system or something on the road or in the conditions. It is possible that even with DSC fully on, the result would be the same. My bet is either something on the road or the cold weather... or a combination.

To the OP... great job not losing control. Many arm chair racing experts you find trolling forums and bashing others would have not recovered.

[bigjae1976]

Originally Posted by username11

The point that is being made is that it is IS the norm for the car to behave this way.

Step 1) Drive with summer tires in 40 degree temperatures where they have very limited traction by design.

Step 2) Turn DSC into a mode that allows a large degree of lateral slip.

Step 3) Make surprised post that car allowed large degree of lateral slip.



No, that's what MDM is supposed to do. Did you read the manual? People think MDM is a DSC plus a little bit of fun; no, you can still crash and the manual explicitly states driver correction is mandatory.



Really now? So in this case the driver selects a mode that is designed to allow the car to go sideways. It does, and you think it is malfunctioning? Then you think the mode which would NOT allow the car to go sideways would not work. Logical.

DSC does not save stupidity. Of all people, you should be made fully aware of that based on your posts.

DSC will not save you in every situation. It is very good but not a cure all.

[gthal]

Originally Posted by username11

The point that is being made is that it is IS the norm for the car to behave this way.

Step 1) Drive with summer tires in 40 degree temperatures where they have very limited traction by design.

Step 2) Turn DSC into a mode that allows a large degree of lateral slip.

Step 3) Make surprised post that car allowed large degree of lateral slip.



No, that's what MDM is supposed to do. Did you read the manual? People think MDM is a DSC plus a little bit of fun; no, you can still crash and the manual explicitly states driver correction is mandatory.



Really now? So in this case the driver selects a mode that is designed to allow the car to go sideways. It does, and you think it is malfunctioning? Then you think the mode which would NOT allow the car to go sideways would not work. Logical.

I won't bother getting into this with you... Suffice it to say I have read the manual and do know how MDM works. It is supposed to allow more slippage than full DSC but even that is limited. Spend some time on the track with the car in MDM and you will know what I mean. It is very hard to rotate this car even with MDM mode on. To be clear, you CAN spin the car even with full DSC. Physics outweighs stability systems on all accounts.

[gthal]

Originally Posted by username11

It will do a (much) better job of preventing lateral slip than driving the car in a mode designed to allow limited lateral slip.

slight modification to your post.

[gthal]

Originally Posted by username11

I think you missed the point. It will do a (much) better job of preventing lateral slip than driving the car in a mode designed to allow lateral slip.

No one said it wouldn't do a better job. What I was saying was that if the situation was severe enough ... Say oil on the road... Then he may have slip even with full DSC. MDM, if you haven't tested it on a track yourself, still limits rotation a lot. Yes, less than DSC fully on but many experienced drivers would still say it interferes early and in a meaningful way. What I was saying is that MDM should reel the car back in in all but the worse scenarios or because something else (loss of traction due to temp, road condition, whatever) interfere and in that case even full on DSC may not have helped. If the tires are sliding and without traction then it may not matter what mode the car is in. I'm sorry if you don't get this.

[DivideBYZero]

Originally Posted by gthal

No one said it wouldn't do a better job. What I was saying was that if the situation was severe enough ... Say oil on the road... Then he may have slip even with full DSC. MDM, if you haven't tested it on a track yourself, still limits rotation a lot. Yes, less than DSC fully on but many experienced drivers would still say it interferes early and in a meaningful way. What I was saying is that MDM should reel the car back in in all but the worse scenarios or because something else (loss of traction due to temp, road condition, whatever) interfere and in that case even full on DSC may not have helped. If the tires are sliding and without traction then it may not matter what mode the car is in. I'm sorry if you don't get this.

Can't you discuss this without getting snarky?

[Ateam]

Originally Posted by DivideBYZero

Can't you discuss this without getting snarky?

he is always on the defensive and a know it all so the answer to that is no

[smmmurf]

Originally Posted by username11

Stupid.

40 degrees and PS2 or CS3s = very limited traction especially in the rear. Why would you be driving around on public roads, temperature too cold for your summer tires, with DSC partially off (MDM)? This thread is evidence that what should have been the expected result was not expected. Missed Darwin award.

I personally think that OP's story is perfectly reasonable driving in 40 degree weather with summer tires. It's not like it was fucking snowing.

DSC was ON. Even if it is in MDM, it will not allow 40 degrees of slip on normal operation...

Originally Posted by Voltigeur

You may not have read the all prior posts [tires were not 'cold']. And if someone on this board thinks someone should die ["missed Darwin award"] from a mishap, then that speaks to something less than stupid. Good on ya mate!

[edit] I most certainly have done very some risky things is my life including sliding a car near a precipice in a 3rd world country - which I would not repeat under any circumstances. But this was not one of those times.

Shit happens: in this case, I was surprised by the 'shit' which motivated the post.

+1.

[gthal]

Originally Posted by DivideBYZero

Can't you discuss this without getting snarky?

I tend to respond in a manner consistent with how I and others are being addressed. I get annoyed, and respond like this, when people start throwing insults, name calling (like telling someone they have no common sense), commenting on "darwin awards" relative to long standing and respected members, etc. It irks me and I get snarky myself... My bad.

Having said that, you are correct and I should have taken a different approach.

[gthal]

Originally Posted by Ateam

he is always on the defensive and a know it all so the answer to that is no

:

[SROC3]

Just chiming in:

I agree though that MDM should only be used on the track. I see no point in risking tail-kick and the possibility of kissing a railing because I thought it was cooler to be on MDM. Even if you drive aggressively on public roads, MDM is not necessary at all.

Having said that, if anyone does drive like that on public roads where they feel that MDM gives them more "yaw" and lateral movement, then that is just idiotic. If you hurt your car, then that's fine (your wallet). You hurt an innocent family in a minivan cause you're too-cool-for-school then how effective do you think "oh I'm sorry" is going to be?

So to directly address the OP and the gist of his post - i think that it could have been oil, poop ar any other variables that may have caused your slippage. Now since you did experience that, make sure your DSC is on at all times to minimize it turing into a nasty incident

[smmmurf]

Originally Posted by gthal

I tend to respond in a manner consistent with how I and others are being addressed. I get annoyed, and respond like this, when people start throwing insults, name calling (like telling someone they have no common sense), commenting on "darwin awards" relative to long standing and respected members, etc. It irks me and I get snarky myself... My bad.

Having said that, you are correct and I should have taken a different approach.

gthal is right. DSC full on and DSC MDM both limit the rotation of the car and it is not possible to access the full capability of the car with the system engaged in any way. Many people lack the skill and/or experience to do so, hence DSC on is a good lowest common denomenator for street driving.

Originally Posted by Voltigeur

Bit mystified but in my experience the car - not just MDM mind - as per my 1st post - when set up w/ throttle/steering/MDM is more responsive. Oh, I see your point: yes, MDM is just DSC-light, I was using it as shorthand for the other settings.

To your specific question: the car feels lighter on its feet and more precise; in some respects I regard it as a safer setting than all-nanny mode. In any case, on this day I did not in any way 'push' hard where the oversteer + correction in MDM was engaged. Frankly, not how I want to commute and as I got closer to the city I normally disengage it.

Perfectly reasonable, and my experience as well. All DSC modes limit acceleration and it is possible to encounter a situation in which DSC cutting power would prevent one from accelerating out of the way of an obstacle or another driver.

Originally Posted by username11

Let me clarify my suggestion of the "Darwin" award. Not that I think someone should die (really, no) from any sort of mishap. But choosing to turn off (or limit) an important safety device, choosing to activate a mode that allows a particular behavior (lateral slip), and then saying oh shit! the car did *exactly* what I just told it to do -- seems pretty dumb. Not sure why that dosen't make more sense to people. Driving with MDM on with summer tires in 40 degree weather is akin to driving with MDM on in pouring rain.

Honestly, given the OP's description of the events, I would think that even DSC on would have allowed the car to slip like that.

It sounds like he hit oil or something. I would have been surprised too driving across dry pavement at above freezing temperatures and having the car oversteer suddenly. I think most people would be. Good thing he recovered it.

The analogy to using launch control into a garage is not nearly comparable and the suggestion of a Darwin Award is unwarranted.

[adc]

OP, also check the tire pressures and see if there are any differences left to right. I did so recently and found about 8psi difference which in 40F weather could make a difference.

I also think I've noticed that the diff can have "off" days - does yours generate any wheel hop? Or did you ever do the full lock turning test at low speeds, to see if you get the grabbing/catching sound?


And to the other guy - I don't have MDM so I tend to disengage DSC completely in the dry and when I'm on my own. DSC stays on when it rains or if I have passengers (also because I am liable to be more distracted then). The reason I disengage it is because it tends to intervene aggressively and cut power even when pointing straight, and I profoundly dislike that.

It is most definitely *not* criminal negligence to turn off DSC, so relax.

[smmmurf]

Originally Posted by adc

OP, also check the tire pressures and see if there are any differences left to right. I did so recently and found about 8psi difference which in 40F weather could make a difference.

I also think I've noticed that the diff can have "off" days - does yours generate any wheel hop? Or did you ever do the full lock turning test at low speeds, to see if you get the grabbing/catching sound?


And to the other guy - I don't have MDM so I tend to disengage DSC completely in the dry and when I'm on my own. DSC stays on when it rains or if I have passengers (also because I am liable to be more distracted then). The reason I disengage it is because it tends to intervene aggressively and cut power even when pointing straight, and I profoundly dislike that.

It is most definitely *not* criminal negligence to turn off DSC, so relax.

+1000.

I do get some wheelhop when going straight and encountering wheelspin (not usually when the car has a lot of yaw in it. The diff has been pretty consistent for me across various surfaces/temperatures and running PS2's and PSS's.

[klammer]

I will second the summer tires in cold temps scenario. I too have on/off ramps I frequent, and about a month ago as I entered the highway, caught a bit of a "tank slapper", first time I've ever encountered it on the street. New it was cold out (high 30's low 40's) and pretty much blamed it on the tires as most other variables were consistent. Put on the winters a week later. Oh.... and contrary to what the media and apparently the public at large think, yes shit does happen, and somebody doesn't always need to be blamed. Happy motoring

[Blue92]

Originally Posted by adc

OP, also check the tire pressures and see if there are any differences left to right. I did so recently and found about 8psi difference which in 40F weather could make a difference.I also think I've noticed that the diff can have "off" days - does yours generate any wheel hop? Or did you ever do the full lock turning test at low speeds, to see if you get the grabbing/catching sound?


And to the other guy - I don't have MDM so I tend to disengage DSC completely in the dry and when I'm on my own. DSC stays on when it rains or if I have passengers (also because I am liable to be more distracted then). The reason I disengage it is because it tends to intervene aggressively and cut power even when pointing straight, and I profoundly dislike that.

It is most definitely *not* criminal negligence to turn off DSC, so relax.

My vote for a very plausable reason for your "ride". Obviously, the likely cuplrits are the rears...

[von_zoom]

Well, I am late joining in, but an observation:

MDM on
More sensitive throttle on
steering too

With your MDM settings as shown, your car is set up for abrupt response and subsequent action. When your throttle is set to a "more sensitive" level, it then becomes more of an ON - OFF switch, and becomes away from normal in throttle application. Even on the track, I discourage this setting from being sensitive, rather, going the other way so feathering the throttle becomes easier with slower weight shift occuring in the car. It is the shift of weight resulting in an unbalance configuration that leads to loss of traction.

Now, I will not say that this setting caused you unpleasant experience, but may have contributed to the combination of possible causes. Cold tires, sensitive steering and throttle, and not ruling out attention to driving, MAY have contributed to the event. Happy you, your car, and others did not experience any bad results.
vz

[soberin]

I don't see what the fuss is about. I never use MDM or de-activate the DSC unless I'm tracking the car or autocrossing. During street driving there is no reason to use MDM or turn off the DSC unless you like to do stupid things with your car.

Who knows what actually happened in this case? It was a situation due to power-oversteer, as a result of loss of rear wheel traction. Maybe the higher intervention threshold of the DSC in MDM mode failed. Anyway, I don't call this type of power-oversteer "snap oversteer." I would call it a driver error by applying too much power in a curve in cold weather. True "snap oversteer" is more common when you load the front of the car under braking, then pop off the brakes too fast and the back comes around. This is how we rotate the car in the left-hander at Lime Rock, but without spinning. This type of spin happens more quickly in than trailing-throttle oversteer, when you pop off the throttle in a turn and the back comes around more slowly, as the front of the car is not already loaded. I would assume that for most drivers, power-oversteer while entering a highway ramp would be the easiest to correct.