[goobus]

So I picked up my car from BMW the other day. Stopped at a light, and as the light turned green I pushed the throttle down about halfway in sport+ mode with the DCT in "3" (not 3rd gear, but the fastest setting) and the car did this weird, very unpleasant bucking motion instead of accelerating smoothly.

Has anyone else experienced this? Is it related to the throttle response in sport+ or the DCT in "3"?

Edit: added clarification that I'm not trying to start the car from 3rd gear

[NISFAN]

Yes, mine does that too in S+. Throttle pedal is too sensitive. I don't go above Sport now.

[Poffman]

Originally Posted by goobus

So I picked up my car from BMW the other day. Stopped at a light, and as the light turned green I pushed the throttle down about halfway in sport+ mode with the DCT in "3" and the car did this weird, very unpleasant bucking motion instead of accelerating smoothly.

Has anyone else experienced this? Is it related to the throttle response in sport+ or the DCT in "3"?

Does it do this when you're in 1st or 2nd?

The DCT is an automated manual, when you started in 3rd in the most aggressive throttle setting, and it's trying to let the clutches out to get you moving. The trans is not going to stall out, but it's going to not be happy being bogged down like that. If you started a 6spd manual car in 3rd and nailed the throttle a bit on a sensitive setting, it's going to react the same way.

[Steelguin]

I think he means the trans is set to shift 3. Hard shift, not third gear. Unless I'm misunderstanding.

[goobus]

Originally Posted by Steelguin

I think he means the trans is set to shift 3. Hard shift, not third gear. Unless I'm misunderstanding.

This is right

[Steelguin]

Yeah you have to feather it a bit and then nail it. That's my experience. I'm not able to leave by flooring it anyway...it just lights up the tires and gets all squirrely.

[boss2k]

Originally Posted by Poffman

Does it do this when you're in 1st or 2nd?

The DCT is an automated manual, when you started in 3rd in the most aggressive throttle setting, and it's trying to let the clutches out to get you moving. The trans is not going to stall out, but it's going to not be happy being bogged down like that. If you started a 6spd manual car in 3rd and nailed the throttle a bit on a sensitive setting, it's going to react the same way.

You cant start a DCT in 3rd gear , computer will auto shift to 1st on stand still, its not an actual MT

[Bumpinjeep]

Skip to the 3:28 mark for your answers

[AZ-Wildcat]

Originally Posted by Bumpinjeep

Skip to the 3:28 mark for your answers

I don't think this guy knows how to drive, or he's putting on an act. This is easily avoidable... you gotta treat that gas pedal like a good woman. Cant come in all hot and jerky thinking its going to end well.

[akkando]

Originally Posted by Bumpinjeep

Skip to the 3:28 mark for your answers

Yeah, this is normal. You have to figure out how to drive it. I'm used to it now. I find I need to be deliberate with the throttle. You don't want to confuse it and ride the clutch. If it does start bucking just take your foot off throttle until it stops then try again. I find it's most likely to happen to me when going up a hill in first gear. Instead of slowly rolling onto onto throttle I just go right to like 25% throttle so the car isn't confused with what I want.

[M2_MEDUSA]

It's like a manual bro it has a clutch. So ease into throttle or you'll get bucked. It's a learning curve but you'll get the throttle control down just like any manual car from a stop

[element241]

Sounds like it could be driver induced throttle oscillation. When you first apply the accelerator pedal, the car starts moving forward initially, causing your foot to lift a little bit off the accelerator pedal. Then, as your foot lifts off the accelerator, the car slows down, causing your foot to crash back into the accelerator pedal and press into it harder. Then the cycle repeats itself and results in the bucking motion you describe. It’s most prone to happen when you have the most aggressive throttle mapping (sensitive accelerator pedal), the most aggressive DCT setting (resulting in the most aggressive initial forward motion to get the cycle started), and you apply partial throttle in an aggressive manner. You can avoid this by using less aggressive throttle/DCT settings, being smoother on the initial accelerator application, letting off the accelerator when it starts to buck, or burying your foot in the throttle so that your foot doesn’t come off the accelerator pedal when the car starts to buck (and thus stops the cycle from repeating).

[Davil]

Why are you in sport+ and shift level 3 at a set of lights? Do you use starting blocks to be first to the checkout at your supermarket? It makes the same amount of sense.

[BigKutta]

Originally Posted by Steelguin

Yeah you have to feather it a bit and then nail it. That's my experience. I'm not able to leave by flooring it anyway...it just lights up the tires and gets all squirrely.

I agree, this is the only way to avoid it. I'd never race anyone from a light because of all this lurching. Give it some gas, as the car gets going then punch it.

Originally Posted by NISFAN

Yes, mine does that too in S+. Throttle pedal is too sensitive. I don't go above Sport now.

My car will lurch even in S mode

[AlpsRider]

The 6MT manual will "buck" as well. I wonder if cars with coilovers have the same problem. It could be a traction control issue also. Anyone have this happen with DSC off?

[goobus]

Sounds like I just need to spend a bit more time with the car. It was hilarious cause I had a truck behind me and he backed way off when he saw me bucking like that..probably a smart move considering I don't really know how to drive this beast yet. Will probably stay in sport mode and transmission level 2 for now.

[Poffman]

Originally Posted by goobus

This is right

Originally Posted by Steelguin

I think he means the trans is set to shift 3. Hard shift, not third gear. Unless I'm misunderstanding.

My bad. I have an OG so no hard shift setting for me

[akkando]

Originally Posted by Davil

Why are you in sport+ and shift level 3 at a set of lights? Do you use starting blocks to be first to the checkout at your supermarket? It makes the same amount of sense.

It's not about racing a Prius from stoplight to stoplight, the settings change the character of the car, the way it feels. The lowest shift setting slips the clutch for smooth shifts. The highest snaps them off quick and rev matched down shifts.

[akkando]

Originally Posted by Poffman

My bad. I have an OG so no hard shift setting for me

Sport+ is basically shift setting 3 on OG.

[JustDrifting]

Originally Posted by AlpsRider

The 6MT manual will "buck" as well. I wonder if cars with coilovers have the same problem. It could be a traction control issue also. Anyone have this happen with DSC off?

Same with my M2C manual - think it's a throttle modulation/software issue. Thought maybe after engine run in it'd ease, but it hasn't (with 3.5k miles on the odometer).

Lurches slightly, even if under constant light throttle. Doesn't matter if in efficient, sport or sport+. Doesn't do it if mashing the throttle/driving hard, just gentle constant throttle....

[gmehrguth]

Originally Posted by M2000

Same with my M2C manual - think it's a throttle modulation/software issue. Thought maybe after engine run in it'd ease, but it hasn't (with 3.5k miles on the odometer).

Lurches slightly, even if under constant light throttle. Doesn't matter if in efficient, sport or sport+. Doesn't do it if mashing the throttle/driving hard, just gentle constant throttle....

I have the same issue. Is this unfixable? Is there a simple throttle map change with a tune? or do I need to just adjust my driving and up shift quicker into second when cruising/casual.

[Commanderwiggin]

My tuner Ian@Bend Calibration sorted the jerky throttle. Can daily drive around in S+ all day without any jerk/buck non-sense.