Power delivery with DSC On - 1st/2nd gear vs. 3rd gear

[Powerslide]

Today I went out for a little drive... Not much slush on the roads this afternoon in my area - mostly water (either because temps slightly above freezing and salt on roads). Given these conditions, I keep DSC fully on.

So on straight stretches of road with little water and DSC on, I tried giving a good amount of throttle from about 2k-4k rpm, and then doing the same in 3rd gear (1st gear under such conditions will obviously cause DSC to intervene quickly and cut engine power at the slightest hint of wheelspin - so I didn't even try this in 1st).

I noticed a BIG difference in how much DSC cuts power in 2nd gear under such conditions vs. 3rd gear - I understand that torque multiplication is going to apply to differences in the gear ratios, but I didn't realize that:

2nd gear pulls at about 50-70% throttle from 2k-about 4-5k rpm gives some wheelspin and cutting of engine power with decent acceleration.

HOWEVER - same thing in 3rd gear - HOLY CRAP!!!! Even with full DSC on, throttle set at efficient and drivelogic set at S2 - borderline savage acceleration with little or no wheelspin!! (Let me clarify though - since 3rd gear is going to have much higher speeds for a given rpm vs. 2nd gear - the "bursts" of acceleration in 3rd gear obviously couldn't last as long.

Just curious if anyone else has noticed such a difference in how the ECU cuts power to a far greater extent in 2nd vs. 3rd gear - I always suspected there was some difference - just nowhere near to the extent I discovered today...

[Accel Junky]

Yes, I've noticed the same thing. The acceleration in lower gears with the traction nannies on is severely compromised and also very inconsistent. When I drove the car on the Nurburging I liked how it would save my bacon but on the streets I'm constantly left wondering where my power is. I guess they have made the car much can safer for novice drivers not used to so much power.

[stressdoc]

I sense a difference from my Euro driving. I wonder if the USA programming interferes more than the set up for ED.

[Xenophon]

I feel the same, but also think it may just be my head playing games with me.

I find myself totally disabling DSC in order to do anything remotely interesting (including accelerate quickly in a straight line below 60mph) which is sub-optimal. MDM is useless as well unless the conditions are perfect (warm tires, 70out and dry), in which case it seems to let an agreeable amount of wiggle happen.

I remember driving aggressively up and down many mountain passes to include Furka and many autobahn runs on ED during which I never went beyond MDM without the same complications... again it could just be my warm memories of the new toy

[chiplee]

Originally Posted by Accel Junky

Yes, I've noticed the same thing. The acceleration in lower gears with the traction nannies on is severely compromised and also very inconsistent. When I drove the car on the Nurburging I liked how it would save my bacon but on the streets I'm constantly left wondering where my power is. I guess they have made the car much can safer for novice drivers not used to so much power.

100% verbatim ditto after the Nurburgring part. I'm to the point where I much prefer efficient mode because the power delivery is so much more gradual that I never get the intrusive cut that comes in Sport+. The car is brutally fast if it hooks and allows full power, but when the nannies are at work it's frustrating. Can't find the happy settings.

[solstice]

My right foot + DSC does a fine job in putting down power ( not to be confused with ALL power ) in all gears, I still don't get these complaints. Good for me I guess, I.e I don't want to understand

[Accel Junky]

Originally Posted by solstice

My right foot + DSC does a fine job in putting down power ( not to be confused with ALL power ) in all gears, I still don't get these complaints. Good for me I guess, I.e I don't want to understand

Yeah, it does what it is supposed to do. The issue is how much power is it cutting to do its job? And how does it go about doing so with seemingly bizarre inconsistency?

[solstice]

Originally Posted by Accel Junky

Yeah, it does what it is supposed to do. The issue is how much power is it cutting to do its job? And how does it go about doing so with seemingly bizarre inconsistency?

Mine doesn't seem to cut power until I got slippage but I tend to roll on the power and also not slam into the gears ( I have MT ) so if it cuts power when it detects sudden extreme drive train stress without slippage as well I wouldn't know since I try to avoid that.

[chiplee]

Originally Posted by solstice

Mine doesn't seem to cut power until I got slippage but I tend to roll on the power and also not slam into the gears ( I have MT ) so if it cuts power when it detects sudden extreme drive train stress without slippage as well I wouldn't know since I try to avoid that.

I think our feeling is that it cuts more power than it should need to to maintain traction. I'm pretty sure if I lined up with my wife's 35i X5 she would hang with me because her car just goes at full power. The m3 cuts power that much when it senses wheel spin.

[solstice]

Originally Posted by chiplee

I think our feeling is that it cuts more power than it should need to to maintain traction. I'm pretty sure if I lined up with my wife's 35i X5 she would hang with me because her car just goes at full power. The m3 cuts power that much when it senses wheel spin.

No way an X5 35i can hang with an M3 with DSC on beyond first gear. I'm starting to wonder if the DSC programming has been changed at some stage? Mine is a July build.

[Accel Junky]

Originally Posted by solstice

Mine doesn't seem to cut power until I got slippage but I tend to roll on the power and also not slam into the gears ( I have MT ) so if it cuts power when it detects sudden extreme drive train stress without slippage as well I wouldn't know since I try to avoid that.

I can be on bone-dry pavement and do a roll run and the power cutting is almost depressing. 6MT as well.

[Hawaii i8]

Fascinating discussion: I wonder if this is simply a reflection of the huge amount of torque this engine develops very low in the rev range. In second gear when accelerating hard even on the bone dry roads where I live the torque is stunning and I am still tying to keep within 55000 revs/110 during my break in period. The car really wants to shimmy and I think the tires struggle to hold traction. If it was not for DSC in 2nd gear I think a lot of us might end up parking our cars into the guard rail. Once in 3rd I think the car has established balance and grip and DST does not need to intervene (Unless you really overdo it) Maybe I'm misunderstanding your point but I'm trying to say I think DSC is doing its job correctly..

[Hawaii i8]

Originally Posted by chiplee

I think our feeling is that it cuts more power than it should need to to maintain traction. I'm pretty sure if I lined up with my wife's 35i X5 she would hang with me because her car just goes at full power. The m3 cuts power that much when it senses wheel spin.

The X5 might hang with you for the first couple of seconds but after that I would hope things would look a lot different. Have you tried launch mode yet? I wonder how the car compares?

I suspect a lot of high Torque cars have issues getting the power down at first. Maybe the rear tires on the M3/M4 are not up to the job?

[chiplee]

Originally Posted by solstice

No way an X5 35i can hang with an M3 with DSC on beyond first gear. I'm starting to wonder if the DSC programming has been changed at some stage? Mine is a July build.

Well of course. I mean from a 25MPH roll there's very little in my town that can hang with the M3. From a dig the thing is doing stupid stuff to the power.

[solstice]

Originally Posted by BigIslandM4

The X5 might hang with you for the first couple of seconds but after that I would hope things would look a lot different. Have you tried launch mode yet? I wonder how the car compares?

I suspect a lot of high Torque cars have issues getting the power down at first. Maybe the rear tires on the M3/M4 are not up to the job?

It's more that pretty much all modern cars have enough power to break traction in first gear so the M3 has no advantage over the AWD X5 here but once in 2nd gear with good throttle modulation you can soon get all power down even with DSC and then you will smoke the X5 and 99% of cars you meet on the street. 3rd gear needs less modulation, hardly none and the X5 is now a blip in your rear mirror.

Just practice rolling on the power if you have problems with it.

[Hawaii i8]

Originally Posted by solstice

It's more that pretty much all modern cars have enough power to break traction in first gear so the M3 has no advantage over the AWD X5 here but once in 2nd gear with good throttle modulation you can soon get all power down even with DSC and then you will smoke the X5 and 99% of cars you meet on the street. 3rd gear needs less modulation, hardly none and the X5 is now a blip in your rear mirror.

Just practice rolling on the power if you have problems with it.

I agree, I think this is all about power modulation, in some ways it will improve all of our driving skills - We cannot simply "mash the accelerator" to the floor if we want optimum acceleration... Kind of fun learning how to drive this awesome machine :-)