Jerky behavior on acceleration after auto-downshifting

Drivaar · 11-27-2010, 09:27 AM

I hope you all had a great Thanksgiving break, where applicable.

I've got a transmission question for y'all:

When I'm cruising on a street road, say at 45 mph in 6th gear, and I see a red light coming up, of course I'll take my foot off the accelerator and let the car slow down.

As the car slows (this is an auto), it keep downshifting to match your speed. So at this point, I'd be in 3rd (for example) at 30 mph.

Then the light turns green, so I press the accelerator gently to speed up. But the car often lurches there -- even a gentle cap of the accelerator seems to get the turbos spinning up fully, and you get a jolt, which is really lame for passengers who are sensitive to those things! (Great for track, but really stupid for cruising.)

What I've found is that each time I take it to the dealer for software programming, this problem goes away and you can smoothly accelerate again with small inputs. But over a few months, the jerkiness always comes back!

I find it really stupid that this car is now like Windows...

I've tried the transmission reset procedure people have described, but I never hear anything and I don't feel any differences in the transmission, especially regarding this problem.

I think a luxury car should be able to handle light throttle input without snapping the passenger's head back!

Anyone else seen this issue?

Thanks for your advice!

J02 335i · 11-27-2010, 01:49 PM

Are you in D or DS?

fherjohn · 11-27-2010, 05:42 PM

I have this same problem in my 328. I just bought it cpo the other day as well.

FVM3 · 11-27-2010, 05:52 PM

happens in my 335i

Drivaar · 11-28-2010, 07:42 PM

I'm in M... D and DS are even worse... which is why I drive in M all the time, so at least I can pick the gears.

Sometimes this lurching thing happens even when there isn't a downshift involved... like being in 6th, slowing down, then gradually applying the accelerator to speed up smoothly. As soon as you touch the accelerator, you get this jump -- basically the same torque that you'd get with full accelerator travel. You can even see the RPM needle jump up oddly, and then it settles back to where it should be...

I guess this doesn't bother too many folks around here.

But these days I have some passengers who are acceleration-sensitive, so it's become more important.

Thanks!

brocken · 11-29-2010, 02:31 PM

I have the same problem you describe. However, mine is usually preceded by a second or two of no throttle response before the jumping occurs. Push down on pedal...wait...wait..wait... jerk!
It's not turbo lag either as there's NO acceleration... the engine itself should make some power even without the turbos working.
I guess my point is that it's not linear. I expect to press 25% and get 25% of a throttle response.

Brian135i · 11-29-2010, 03:52 PM

I had the same problem, but now it's gone. With my Procede, I reset all adaptations in the command center. The car drive 1000x better. :-)

11-27-2010, 09:27 AM	#1
Drivaar Lieutenant 81 Rep 463 Posts Drives: BMW Join Date: Aug 2010 Location: Earth iTrader: (0)	Jerky behavior on acceleration after auto-downshifting I hope you all had a great Thanksgiving break, where applicable. I've got a transmission question for y'all: When I'm cruising on a street road, say at 45 mph in 6th gear, and I see a red light coming up, of course I'll take my foot off the accelerator and let the car slow down. As the car slows (this is an auto), it keep downshifting to match your speed. So at this point, I'd be in 3rd (for example) at 30 mph. Then the light turns green, so I press the accelerator gently to speed up. But the car often lurches there -- even a gentle cap of the accelerator seems to get the turbos spinning up fully, and you get a jolt, which is really lame for passengers who are sensitive to those things! (Great for track, but really stupid for cruising.) What I've found is that each time I take it to the dealer for software programming, this problem goes away and you can smoothly accelerate again with small inputs. But over a few months, the jerkiness always comes back! I find it really stupid that this car is now like Windows... I've tried the transmission reset procedure people have described, but I never hear anything and I don't feel any differences in the transmission, especially regarding this problem. I think a luxury car should be able to handle light throttle input without snapping the passenger's head back! Anyone else seen this issue? Thanks for your advice!
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11-27-2010, 01:49 PM	#2
J02 335i Lieutenant Colonel 43 Rep 1,559 Posts Drives: F80 M3 Join Date: Aug 2010 Location: Ontario iTrader: (1)	Are you in D or DS? __________________ Sport pack, JB3, Dci, factory oil cooler, 18" M3 reps, Michelin PSS, painted trim, black grills, smoked side markers, LED plate lights, H&R coils, Borla catback
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11-27-2010, 05:42 PM	#3
fherjohn Lieutenant 33 Rep 532 Posts Drives: m3 e93 Join Date: Nov 2010 Location: San diego iTrader: (6)	I have this same problem in my 328. I just bought it cpo the other day as well.
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11-27-2010, 05:52 PM	#4
FVM3 Major General 295 Rep 5,751 Posts Drives: e92 m3, f30 328i Join Date: Sep 2010 Location: Los Angeles iTrader: (2)	happens in my 335i
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11-28-2010, 07:42 PM	#5
Drivaar Lieutenant 81 Rep 463 Posts Drives: BMW Join Date: Aug 2010 Location: Earth iTrader: (0)	I'm in M... D and DS are even worse... which is why I drive in M all the time, so at least I can pick the gears. Sometimes this lurching thing happens even when there isn't a downshift involved... like being in 6th, slowing down, then gradually applying the accelerator to speed up smoothly. As soon as you touch the accelerator, you get this jump -- basically the same torque that you'd get with full accelerator travel. You can even see the RPM needle jump up oddly, and then it settles back to where it should be... I guess this doesn't bother too many folks around here. But these days I have some passengers who are acceleration-sensitive, so it's become more important. Thanks!
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11-29-2010, 02:31 PM	#6
brocken Captain 43 Rep 622 Posts Drives: X3MC Join Date: Nov 2006 Location: Seattle, WA iTrader: (5)	I have the same problem you describe. However, mine is usually preceded by a second or two of no throttle response before the jumping occurs. Push down on pedal...wait...wait..wait... jerk! It's not turbo lag either as there's NO acceleration... the engine itself should make some power even without the turbos working. I guess my point is that it's not linear. I expect to press 25% and get 25% of a throttle response.
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11-29-2010, 03:52 PM	#7
Brian135i Lieutenant 49 Rep 469 Posts Drives: BMW 16' M3 Join Date: Aug 2009 Location: Oxnard, CA iTrader: (1) Garage List 2009 BMW 135i [0.00]	I had the same problem, but now it's gone. With my Procede, I reset all adaptations in the command center. The car drive 1000x better. :-)
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