Instantly mashing accelerator on high gear, bad battery dct shifting

Jay-K · 06-28-2017, 10:12 PM

My car feels light hesitations (i dont know the right words of describing this) on 1000-2000rpm when throttle was hit hard from 1000 rpm rolling start.

I have an understanding that this is similar situation of being to high in gear but low in rpm and speed in a manual car.

However after 2000rpm no matter what gear car runs greatly. I can easily fix this issue by changing to manual mode, where most of the time rpm is above 2k.

What i see is maybe when i accelerate instantly the dct is late to downshift the gear to get rpm high, because by mashing the pedal down it should down shift instantly to lower gear that sets the rpm at 2-3k.
----------

I read some stuff about my battery being very low will affect electrical stuff in the car. Because i used to have an f10 m5 where the dct shifts so slow due to bad battery, changed it and all is good. Is it possible that due to bad battery my dct downshifts late and cause these acceleration in unwanted gears.

I also read somewhere in this forum that when you are giving much load to the engine in high gear it might drive the knock control system crazy and cause this.

Thanks,

Jay-K · 06-30-2017, 12:34 AM

Bump? Nothing ?

TWiTCHY · 06-30-2017, 01:57 AM

Unclear if the hesitation you're feeling is from the transmission or traction control kicking in.

If you're expecting the car to shift quicker than a traditional automatic from, say, 7th directly to the lowest possible gear (let's say 3rd) chances are the DCT is not prepared for that. The job of the DCT is to prepare for the next predicted gear. If you're cruising in 7th, the next prepped gear is probably 6th, not 3rd, so it will take time for the transmission to "get rid" of 6th and then grab 3rd for you. Just because it's a DCT doesn't mean every single gear shift is going to be the same quick speed. The DCT has an algorithm to guess your next gear, and if it guesses wrong, your shift into your desired gear won't be as quick as the gear it had already prepared for you.

Somebody correct me if I'm wrong..

Jay-K · 06-30-2017, 02:01 AM

Quote:

Originally Posted by TWiTCHY

Unclear if the hesitation you're feeling is from the transmission or traction control kicking in.

If you're expecting the car to shift quicker than a traditional automatic from, say, 7th directly to the lowest possible gear (let's say 3rd) chances are the DCT is not prepared for that. The job of the DCT is to prepare for the next predicted gear. If you're cruising in 7th, the next prepped gear is probably 6th, not 3rd, so it will take time for the transmission to "get rid" of 6th and then grab 3rd for you. Just because it's a DCT doesn't mean every single gear shift is going to be the same quick speed. The DCT has an algorithm to guess your next gear, and if it guesses wrong, your shift into your desired gear won't be as quick as the gear it had already prepared for you.

Somebody correct me if I'm wrong..

Definitely not a traction control kicking in, thanks for the dct explanation.

Hesitation more like power delivery is not smooth, so it goes thru 1000-2000 slightly rough but gone if we let go or reduce load. But above 2k no issue

TWiTCHY · 06-30-2017, 02:15 AM

Quote:

Originally Posted by Jay-K

Quote:

Originally Posted by TWiTCHY

Unclear if the hesitation you're feeling is from the transmission or traction control kicking in.

If you're expecting the car to shift quicker than a traditional automatic from, say, 7th directly to the lowest possible gear (let's say 3rd) chances are the DCT is not prepared for that. The job of the DCT is to prepare for the next predicted gear. If you're cruising in 7th, the next prepped gear is probably 6th, not 3rd, so it will take time for the transmission to "get rid" of 6th and then grab 3rd for you. Just because it's a DCT doesn't mean every single gear shift is going to be the same quick speed. The DCT has an algorithm to guess your next gear, and if it guesses wrong, your shift into your desired gear won't be as quick as the gear it had already prepared for you.

Somebody correct me if I'm wrong..

Definitely not a traction control kicking in, thanks for the dct explanation.

Hesitation more like power delivery is not smooth, so it goes thru 1000-2000 slightly rough but gone if we let go or reduce load. But above 2k no issue

Maybe what you're feeling is the VANOS kicking in at higher RPMs, but you're noticing the lack of it at low revs rather than its presence at higher revs.

Jay-K · 06-30-2017, 05:09 AM

Quote:

Originally Posted by TWiTCHY

Quote:

Originally Posted by Jay-K

Quote:

Originally Posted by TWiTCHY

Unclear if the hesitation you're feeling is from the transmission or traction control kicking in.

If you're expecting the car to shift quicker than a traditional automatic from, say, 7th directly to the lowest possible gear (let's say 3rd) chances are the DCT is not prepared for that. The job of the DCT is to prepare for the next predicted gear. If you're cruising in 7th, the next prepped gear is probably 6th, not 3rd, so it will take time for the transmission to "get rid" of 6th and then grab 3rd for you. Just because it's a DCT doesn't mean every single gear shift is going to be the same quick speed. The DCT has an algorithm to guess your next gear, and if it guesses wrong, your shift into your desired gear won't be as quick as the gear it had already prepared for you.

Somebody correct me if I'm wrong..

Definitely not a traction control kicking in, thanks for the dct explanation.

Hesitation more like power delivery is not smooth, so it goes thru 1000-2000 slightly rough but gone if we let go or reduce load. But above 2k no issue

Maybe what you're feeling is the VANOS kicking in at higher RPMs, but you're noticing the lack of it at low revs rather than its presence at higher revs.

I cant tell vanos kicking in sound like so i dont know the answer. But just worried this might get worst or sign of something major.

Jay-K · 06-30-2017, 10:13 PM

Quote:

Originally Posted by DrFerry

Spark plug gap?

Might try to change ? Spark plug ? Car is 4 yo w 2600 miles dont think its due alrdy

111turbo · 07-01-2017, 04:59 PM

In auto mode from a dig it does seem to feel alittle bogged down from 1k-2k rpm and im pretty sure its normal. I rarely drive it in auto anyway and even after I changed battery it felt the same. Nothing to worry about imo.

Jay-K · 07-01-2017, 08:56 PM

Quote:

Originally Posted by 111turbo

In auto mode from a dig it does seem to feel alittle bogged down from 1k-2k rpm and im pretty sure its normal. I rarely drive it in auto anyway and even after I changed battery it felt the same. Nothing to worry about imo.

Thanks for the comment, glad to hear

06-28-2017, 10:12 PM	#1
Jay-K Brigadier General 405 Rep 3,450 Posts Drives: Slow Join Date: Nov 2011 Location: LA iTrader: (0)	My car feels light hesitations (i dont know the right words of describing this) on 1000-2000rpm when throttle was hit hard from 1000 rpm rolling start. I have an understanding that this is similar situation of being to high in gear but low in rpm and speed in a manual car. However after 2000rpm no matter what gear car runs greatly. I can easily fix this issue by changing to manual mode, where most of the time rpm is above 2k. What i see is maybe when i accelerate instantly the dct is late to downshift the gear to get rpm high, because by mashing the pedal down it should down shift instantly to lower gear that sets the rpm at 2-3k. ---------- I read some stuff about my battery being very low will affect electrical stuff in the car. Because i used to have an f10 m5 where the dct shifts so slow due to bad battery, changed it and all is good. Is it possible that due to bad battery my dct downshifts late and cause these acceleration in unwanted gears. I also read somewhere in this forum that when you are giving much load to the engine in high gear it might drive the knock control system crazy and cause this. Thanks, __________________ "Well, there's a straight-six engine at the front, a manual gearbox in the middle and drive goes to the back. That's Page 1, Chapter 1 from the petrosexual handbook" - JC
	Appreciate 0 Tweet Quote

06-30-2017, 12:34 AM	#2
Jay-K Brigadier General 405 Rep 3,450 Posts Drives: Slow Join Date: Nov 2011 Location: LA iTrader: (0)	Bump? Nothing ? __________________ "Well, there's a straight-six engine at the front, a manual gearbox in the middle and drive goes to the back. That's Page 1, Chapter 1 from the petrosexual handbook" - JC
	Appreciate 0 Quote

06-30-2017, 01:57 AM	#3
TWiTCHY Colonel 433 Rep 2,527 Posts Drives: '13 AW E92 M3 Join Date: Jul 2008 Location: WA iTrader: (6)	Unclear if the hesitation you're feeling is from the transmission or traction control kicking in. If you're expecting the car to shift quicker than a traditional automatic from, say, 7th directly to the lowest possible gear (let's say 3rd) chances are the DCT is not prepared for that. The job of the DCT is to prepare for the next predicted gear. If you're cruising in 7th, the next prepped gear is probably 6th, not 3rd, so it will take time for the transmission to "get rid" of 6th and then grab 3rd for you. Just because it's a DCT doesn't mean every single gear shift is going to be the same quick speed. The DCT has an algorithm to guess your next gear, and if it guesses wrong, your shift into your desired gear won't be as quick as the gear it had already prepared for you. Somebody correct me if I'm wrong..
	Appreciate 0 Quote

07-01-2017, 04:59 PM	#8
111turbo Private First Class 84 Rep 130 Posts Drives: '12 e92 M3 Join Date: Jan 2015 Location: NY iTrader: (1)	In auto mode from a dig it does seem to feel alittle bogged down from 1k-2k rpm and im pretty sure its normal. I rarely drive it in auto anyway and even after I changed battery it felt the same. Nothing to worry about imo.
	Appreciate 0 Quote