Odd throttle response!

[ManiacGT]

Anyone ever pressed the throttle, 35i DCT, and the engine hasn't responded for a second or two? I've gone around a local roundabout (it's a euro thing!) twice now and when pressing the throttle the car has continue to coast for a couple of seconds before revs come up and the DCT has selected quite a high gear. It leaves me with 2" of throttle pedal producing 1" of power if you know what I mean.

Has this happened to anyone else? Might have it in to the dealers to see if there's some sort of throttle/gear issue...

[Constant.S]

Originally Posted by ManiacGT

Anyone ever pressed the throttle, 35i DCT, and the engine hasn't responded for a second or two? I've gone around a local roundabout (it's a euro thing!) twice now and when pressing the throttle the car has continue to coast for a couple of seconds before revs come up and the DCT has selected quite a high gear. It leaves me with 2" of throttle pedal producing 1" of power if you know what I mean.

Has this happened to anyone else? Might have it in to the dealers to see if there's some sort of throttle/gear issue...

Of course, if you are on "Normal mode" the car tends to stay on higher gear, try it by moving the shifter towards the left (go on S gear mode) and/or having the programming to Sport or Sport+. If you still get the gear lag you're talking about, then something might be wrong.

[Memphis1]

Is the roundabout really fast? It might be the ESP holding you back to make sure you don't oversteer

[ManiacGT]

It is like stability is kicking in, taking power from me, but I'm doing perhaps 20mph, nothing fast. I wait to enter the roundabout, press the throttle to enter the roundabout at 20mph, turn right 270 degrees while coasting, press the throttle again to exit the roundabout and, nothing, no power, then (usually as I think it's stalled!) power comes back a couple of seconds later slowly in a very high gear and i cruise out of the exit.

It feels like I'm being ignored! Lol

[Gunzaro]

DCT lag

[Memphis1]

i doubt that's ESP or DCT lag, i have a couple similar roundabouts here and both are 20 to 30mph but my car responds correctly.

[Dr Stig 2]

I've noticed a similar hesitancy in the throttle response.
Annoying, but not deal breaking.
I could keep it in sports plus, but I tend to save that for when I plan to be naughty.

[Gunzaro]

Even with flash tuned (also increases throttle response) Z4 it has this lag. Therefore it is the DCT transmission software programming.

This is gone in Sport+ mode BTW.

[HerrK]

Did quite a few roundabouts during 1800 miles on our ED. Never noticed any throttle lag or improper gear selection with the 35i & 6MT. Must be DCT/ECU/DTC related probably to much information for Watson to process. Might try isolating the problem - Manual shift, DTC off, or Sport mode. Try them one at a time and see which one (hopefully) eliminates the problem.

[ManiacGT]

Originally Posted by Memphis1

i doubt that's ESP or DCT lag, i have a couple similar roundabouts here and both are 20 to 30mph but my car responds correctly.

That's interesting.. It happened again last night, a spurt of throttle away from the lights, then coast for a second or two, then throttle, nothing for 1 to 2 seconds (this feels like a very long time indeed) then power and off we go.

Now DCT lag has been mentioned, I've looked it up on these forums, seems common.

Its reassuring its not just me, but then its worrying that when I need to get out of the way fast... I might not be able to! Think its a dealer conversation... Crikey this car has personality (read too many problems).

[T89]

Hesitation or jerks? Have you tried resetting your transmission (adaptive driver memory for the transmission)?

1. hit start button once to turn on power (Don't start the engine)
2. then press the accelerator down to the floor for 5 sec
3. then hit start button once to turn off power
4. then remove foot from accelerator
5. then wait for 2 minutes
4. then start the engine, drive away.

Resets transmission and throttle response to default.

hope this helps.


T

[Dr Stig 2]

Good to know. Thanks.
Pity I don't know how to make this kind of tip a sticky or to flag it so I can find it when I need it.

[Rubber Ducky]

Drive in Sport. Problem solved. It's to eliminate any throttle hesitation that I always drive in Sport.

[ManiacGT]

The only problem with driving in sport/sport+ is that the suspension is too hard for city driving (Manchester is potholed). I'll try the reset suggestion, and if no better, its back to the dealer lol

[teagueAMX]

Originally Posted by ManiacGT

That's interesting.. It happened again last night, a spurt of throttle away from the lights, then coast for a second or two, then throttle, nothing for 1 to 2 seconds (this feels like a very long time indeed) then power and off we go.

No, this is definitely not a Normal vs Sport modes program setting issue. I know I've heard of this issue before in other makes/models but can't quite put my finger on it. There a number things that could be responsible for that behavior:

-- Fuel supply interruption
-- Poor electrical connection
-- Defective throttle peddle
-- ECU problem
-- DCT programing
-- . . .

The list could go on for a while but I think you get the picture. What I hear you describing is a car that runs normal out of the gate, then all of a sudden throttle response goes flat or there's no throttle response at all.

There was a discussion on the M3 forum about a hesitation issue with the DCT programing, such that just before a down shift the car would hesitate like it couldn't figure out what gear is was supposed to be in. It could be a DCT programing issue but sounds different than that, but do you think the car may be ready to shift to the next highest gear and then hesitates?

[ManiacGT]

The more I read about the DCT lag, the more I think that explains it. I've not looked at the display when it doesn't respond, as to be honest, I panicked into a slight cat in headlights mode wondering whether it was going to die on me etc.

Its only at slow speed, after accelerating a little, then coasting, then attempting to accelerate again. No problems at any other time. It appears to mirror what the M3 lot had to deal with until recently, so I'm wondering if I took have older software as my car was a mid 2009 build, and most people on the M3 board say the latest end-2010 software solved it for them.

Either way, as my local dealer is less than a mile from my office, I'll pop it in next week for their opinion. As I say, a car full of 'character'!

[mcbeee]

Call them up and see if there is a software upgrade you may have missed...

[teagueAMX]

Originally Posted by ManiacGT

The more I read about the DCT lag, the more I think that explains it. I've not looked at the display when it doesn't respond, as to be honest, I panicked into a slight cat in headlights mode wondering whether it was going to die on me etc.

Its only at slow speed, after accelerating a little, then coasting, then attempting to accelerate again. No problems at any other time. It appears to mirror what the M3 lot had to deal with until recently, so I'm wondering if I took have older software as my car was a mid 2009 build, and most people on the M3 board say the latest end-2010 software solved it for them.

Either way, as my local dealer is less than a mile from my office, I'll pop it in next week for their opinion. As I say, a car full of 'character'!

I admit I've been reading this thread on and off, but when you described the problem as:

. . .a spurt of throttle away from the lights, then coast for a second or two, then throttle, nothing for 1 to 2 seconds (this feels like a very long time indeed) then power and off we go.

it really clicked for me and I know if you describe the problem the same way, in very simple, clear terms to your mechanic it will click for him too. The key is explaining a dead spot after you've already taken off, lift off throttle slightly and then nothing.

They are accustomed to people complaining about turbo lag, and if they sense even for a second that's what you're talking about, their knee jerk reaction will be to drop you in that cubby hole and you'll never get out. Explain that "I'm perfectly happy with my engine's off idle throttle response and acceleration". This will firmly boot you out of the turbo lag complainer club and force them to really think about the problem.

Hopefully, as suggested by others it's a simple software patch.

Cheers and good luck.

[ManiacGT]

Well after reading lots about DCT lag on the M3 forums, I decided to press the local dealership on this... they confirmed after taking my car this morning that indeed there is a software update available (announced end of December 2010) and my DCT is being reprogrammed right now. So anyone on here looking for a snappier DCT change might want to get in touch with their dealer also.

[MikeChrista]

Thanks for that extremely useful info. Do you have the BMW nomenclature of the upgrade so I can ask my dealer for it?

[ManiacGT]

No documentation I'm afraid, I'll ask them tomorrow if they can give me the code for the update. You might want to check out the m3 forums for DCT LAG as that's how I discovered the update, that might have the detail you need.

[bill123]

Not noticed any Lag on my iS