DCT LAG

[oman135]

guys i noticed today under WOT i shifted manually from 1st to 2nd and noticed a lag/jerk , my friend has a e92 m3 and he says he has the same problem ?
dct owners do u have this problem . between it doesn't happen always but sometimes
and at what rpm should i change gears to get the best acceleration ?


cheers!

[Aries932]

Originally Posted by oman135

guys i noticed today under WOT i shifted manually from 1st to 2nd and noticed a lag/jerk , my friend has a e92 m3 and he says he has the same problem ?
dct owners do u have this problem . between it doesn't happen always but sometimes
and at what rpm should i change gears to get the best acceleration ?


cheers!

I actually just noticed this for the first time today. Now granted my car only has 800 miles on it, but still....it happened shifting at around 5k rpms. The one thing that I could think of causing this though is if you take your foot off the gas a bit before the shift.

From my understanding in order for DCT to work properly you have to keep your foot on the gas when you upshift and keep your foot on the brake or gas when you downshift. If at any point you take your foot off the DCT bogs.

This could be because it preselects gears....i have no clue...but i do notice coming from driving a manual E46 M3 that i have a tendancy to take my foot of the gas to shift every now and then.

[eleven11]

Just curious, did you have the Sport button engaged?

[Aries932]

Originally Posted by eleven11

Just curious, did you have the Sport button engaged?

umm I do not believe so...i dont remember tho to be honest. Pretty sure i didnt.

[eleven11]

Originally Posted by Aries932

umm I do not believe so...i dont remember tho to be honest. Pretty sure i didnt.

Try it out with the Sport button engaged - see if you can reproduce the same jerk. Also, I agree that constant or increasing throttle levels should be maintained with the DCT.

[oman135]

I had the sport button on i shifted at 7k

[XCC Motorsports]

Yep. Noticed this as well with sport button engaged. It almost feels like fuel cut or traction control kicking in.

It feels like sometimes it happens and other times it doesn't. Stumped.

Originally Posted by oman135

I had the sport button on i shifted at 7k

[oman135]

Originally Posted by XCC Motorsports

Yep. Noticed this as well with sport button engaged. It almost feels like fuel cut or traction control kicking in.

It feels like sometimes it happens and other times it doesn't. Stumped.

. Yap exactly !

[gmartan]

Originally Posted by oman135

guys i noticed today under WOT i shifted manually from 1st to 2nd and noticed a lag/jerk , my friend has a e92 m3 and he says he has the same problem ?
dct owners do u have this problem . between it doesn't happen always but sometimes
and at what rpm should i change gears to get the best acceleration ?


cheers!

It happens whenever you take the foot off the gas and then resume. It's really frustrating when you slow into a corner and hope to power out of it. By the time the engine resumes you have coasted around the corner. No fun.

Have you also noticed the same delay when you step on the pedal from a full stop? I have had delays from one to three seconds before the power surge comes on. That can be very scary when you plan to jump into traffic or cross a busy street. I suspect this is all more a crappy drive-by-wire implementation.

[oman135]

Yap i have the same problem ! Esp full throttel from a stop

[XCC Motorsports]

YEP! It's amplified even worse with the A/C on. Dangerous when pulling out into heavy traffic.

Have you also noticed the same delay when you step on the pedal from a full stop? I have had delays from one to three seconds before the power surge comes on. That can be very scary when you plan to jump into traffic or cross a busy street. I suspect this is all more a crappy drive-by-wire implementation.

[BSM 335I]

This will happen with any automatic transmission for the most part. As mentioned above the gear change is meant to be consistent with the engine speed. Therefore the more momentum you have the easier the transmission can shift, thus resulting in a quick and crisp gear change.

If any one has ever driven a manual here you would know that the same thing applies when you shift at a lower RPM or let the RPM's drop between shifts....you get that jerky/laggy feel. You just notice it more in automatic equipped cars as it's doing all the work for you.

Now if your problem is flooring it from 1st gear and when it shifts to 2nd it cuts power....turn off your DTC. Just be ready to hang on to that wheel.

[oman135]

Originally Posted by BSM 335I

This will happen with any automatic transmission for the most part. As mentioned above the gear change is meant to be consistent with the engine speed. Therefore the more momentum you have the easier the transmission can shift, thus resulting in a quick and crisp gear change.

If any one has ever driven a manual here you would know that the same thing applies when you shift at a lower RPM or let the RPM's drop between shifts....you get that jerky/laggy feel. You just notice it more in automatic equipped cars as it's doing all the work for you.

Now if your problem is flooring it from 1st gear and when it shifts to 2nd it cuts power....turn off your DTC. Just be ready to hang on to that wheel.

yap i tried disabling the traction control it did not cut the power !
but u have to disable full traction control because if juss press then dsc one time it will still cut the power under WOT!

[BSM 335I]

Originally Posted by oman135

yap i tried disabling the traction control it did not cut the power !
but u have to disable full traction control because if juss press then dsc one time it will still cut the power under WOT!

Correct. The DTC button must be held down for more than 3sec to completely disengage it I believe.

[oman135]

Originally Posted by BSM 335I

Correct. The DTC button must be held down for more than 3sec to completely disengage it I believe.

yap! it keeps spinning though !

[BSM 335I]

Originally Posted by oman135

yap! it keeps spinning though !

I assume your referring to yours tires lol. If so power reduction isn't your problem, traction is.

[oman135]

i need new tires

[C135]

I've read all the above posts now and I agree on some and think that others are based on lack of experience. All semi-automatic/automatic gearboxes have some issues, and they are set up slightly differently. The gearbox in the California and 458 Italia has its flaws, same with E-gear in Gallardo and DSG in VW's. I know from first hand experience

All in all I love the DCT in my 135, and all it takes is a little getting used to, and you won't have a single issue. The biggest problem as I see it, is that when for example floor it in normal D mode, and then let off, it will change gears up until you reach normal rpm, for me flooring it in 2nd and letting off will make it change rapidly up to 5th. Then if you're in traffic and the situation calls for an immediate acceleration right after you got off the gas, it will have to change down again to provide the relevant acceleration. This can somewhat be cured by setting it in sport mode (gear selector to the left) but not engaging "M" mode by pulling the paddles or the gear selector. It will keep assume that you are going to get at the gas soon after and wait with the upshifting.

So instead you keep it manual and drive it as a manual. I haven't had any issues in my 4000 miles. But as said, letting off the gas will make it change slow and soft, but I would say more for upshifts rather than downshifts.
Also stated, I agree turning off DTC completely will not cause for any DTC kick in under hard acceleration, but watch out for that torque in slow city traffic, it is quite tail-happy!

Enjoy one of the best double clutch gearboxes in my opinion!

[gmartan]

Originally Posted by C135

I've read all the above posts now and I agree on some and think that others are based on lack of experience. All semi-automatic/automatic gearboxes have some issues, and they are set up slightly differently. The gearbox in the California and 458 Italia has its flaws, same with E-gear in Gallardo and DSG in VW's. I know from first hand experience

All in all I love the DCT in my 135, and all it takes is a little getting used to, and you won't have a single issue. The biggest problem as I see it, is that when for example floor it in normal D mode, and then let off, it will change gears up until you reach normal rpm, for me flooring it in 2nd and letting off will make it change rapidly up to 5th. Then if you're in traffic and the situation calls for an immediate acceleration right after you got off the gas, it will have to change down again to provide the relevant acceleration. This can somewhat be cured by setting it in sport mode (gear selector to the left) but not engaging "M" mode by pulling the paddles or the gear selector. It will keep assume that you are going to get at the gas soon after and wait with the upshifting.

Funny. My Acura TL with auto does not do this. It responds immediately as expected. With the BMW, coming into a corner in third gear then taking your foot off the gas before resuming to power out of the corner does not result in a gear change, just the lag in throttle response.

[emre]

Originally Posted by gmartan

Have you also noticed the same delay when you step on the pedal from a full stop? I have had delays from one to three seconds before the power surge comes on. That can be very scary when you plan to jump into traffic or cross a busy street. I suspect this is all more a crappy drive-by-wire implementation.

I am having this issue since day 1 but the weird thing is it got even worse over the time. The delay was like 1 second but now it takes at least double the time till the car gets going.

Has anyone experienced such a thing. My car is bone stock with 6000kms (3700miles) and never had any updates.

It is a bit less obvious when I let off the throttle and step back on but still it is there.

It helps a bit but not much even with the sports button pressed in M or S mode.

[Aries932]

It is not a problem with the transmission. It is traction control being engaged to stop slipping. I run with DTC completely off (hold the button for 3 seconds) and I never have this issue.

With sports mode engaged this definitely happens because the the faster the shift the more likely the car is to chirp the tires on the shift.

As for the power surge...the car is meant to be to react in that way. It is slowly engaging the clutch for a smooth take off. If it was taken off any faster you would have a really jerky take off every single time you accelerated from a stop. If you want a faster take off then use launch control. Also you should really never need to jump into traffic that fast. If you do that is just dangerous and you should rather wait for a time that you do not need to speed into traffic.

[vase330]

This happens on my AT 335i. The PROCede eliminates this so not sure why BMW doesn't.