[RobUK]

Originally Posted by Jack_is_Back

I get the comfort hesitation in my 340i - it can be very annoying, dangerous even.

Most noticable when say approaching a roundabout; gently braking, almost to a stop, then quickly off the brake and onto the throttle to make a gap and.... NOTHING!!! I can get my foot all the way to the floor with no reaction, it's that ponderous.

As said, I've learnt to drive around it, usually by flicking the lever into Sport when I anticipate I might need a quick getaway. Picks up almost instantly then.

I'm in Comfort 70% of the time and never experienced this

Only time I've ever had anything like was when I ran a 2005 Aldi A3 2.0 TDi with the DSG box - that used to do exactly what you describe, and yes it was bloody dangerous.

[Hooded]

Originally Posted by 330XDave

Like has been mentioned it seems some cars are better/worse than others.

Indeed .. I tried hard to replicate while out driving today what's been mentioned in this thread about the dangerous non responsive throttle if you stop at a junction/roundabout and then a second or 2 later try and pull away. I could not replicate the problem in comfort mode on my car. Yes there is the slightest of delay if you stop dead and then immediately try and pull away, but I mean it's literally approximately 0.5 seconds or so delay and certainly not the dangerous unresponsiveness described by a couple of people in this thread.

It does seem to only be a problem with certain cars and not all, so I wonder what the exact cause is.

[Jack_is_Back]

If I come to a dead stop it's fine, pulls away almost instantly.

It's when you don't quite come to a stop that it occurs. It's almost like the car is preparing itself to idle, but instead you jump on the throttle and catch it out. My 330d was exactly the same so I assumed it was a "feature".

Somebody mentioned about the revs flaring akin to a clutch slipping, but both mine don't do that, I just get a long pause where the car does nothing. I'd estimate it can be over a second at times.

[Hooded]

Originally Posted by Jack_is_Back

If I come to a dead stop it's fine, pulls away almost instantly.

It's when you don't quite come to a stop that it occurs. It's almost like the car is preparing itself to idle, but instead you jump on the throttle and catch it out. My 330d was exactly the same so I assumed it was a "feature".

Somebody mentioned about the revs flaring akin to a clutch slipping, but both mine don't do that, I just get a long pause where the car does nothing. I'd estimate it can be over a second at times.

I see, .. I don't get any delay what so ever if I almost come to a stop .. my 330d responds instantly.

[Jack_is_Back]

I must have got two shitters in a row. Lucky me. Actually the M135i was fine so just 2 out of 3

Not too bothered now, it's become second nature to slip into Sport at certain roundabouts/junctions.

[Jack_is_Back]

I must have got two shitters in a row. Lucky me. Actually the M135i was fine so just 2 out of 3

Not too bothered now, it's become second nature to slip into Sport at certain roundabouts/junctions.

[HighlandPete]

Originally Posted by Jack_is_Back

If I come to a dead stop it's fine, pulls away almost instantly.

It's when you don't quite come to a stop that it occurs. It's almost like the car is preparing itself to idle, but instead you jump on the throttle and catch it out. My 330d was exactly the same so I assumed it was a "feature".

Somebody mentioned about the revs flaring akin to a clutch slipping, but both mine don't do that, I just get a long pause where the car does nothing. I'd estimate it can be over a second at times.

I do wonder if in some cases it literally does get caught out. Applied throttle force/speed/position takes too long to be interrogated before responding. As if it takes time to compare threshold values, ahead of directing throttle response and shift selection.

If this is the case, it makes sense to why a throttle reset works in some cases. A default setting may work better than once it adapts.

[Wills2]

There are plenty of ghosts in the ZF8 machine, nothing is perfect.

[Wills2]

Originally Posted by Jack_is_Back

I get the comfort hesitation in my 340i - it can be very annoying, dangerous even.

Most noticable when say approaching a roundabout; gently braking, almost to a stop, then quickly off the brake and onto the throttle to make a gap and.... NOTHING!!! I can get my foot all the way to the floor with no reaction, it's that ponderous.

As said, I've learnt to drive around it, usually by flicking the lever into Sport when I anticipate I might need a quick getaway. Picks up almost instantly then.

Agreed my old 5 series used to do this in that exact scenario, everyday at the same place!

[HighlandPete]

Originally Posted by Wills2

Agreed my old 5 series used to do this in that exact scenario, everyday at the same place!

What you illustrate does indicate it is directly influenced by real time inputs. The fact it is repeatable in the same conditions, suggests nothing in particular may be wrong with the transmission, more an interpretation of inputs.

I have always suspected this is a key reason some drivetrains have the issues reported. Whether it is tolerances of components, the combination of the build stack and sensitivities to driving environment and/or driver influences, limitations of software and computing power, is hard to quantify.

My 330d with the ZF 6-speed AT had one quirk, which I could repeat every day if I wanted to. Pulling out of my lane on a cold transmission, triggered if I almost needed to stop. Simply how I applied the throttle, either caused a jolt, or was a smooth pull away. As another poster has commented...

Originally Posted by NanasBack

...If you actually stop and need to get off smartish, I move my left foot onto the brake and tap the throttle slightly with my right.

That's similar to what I would do, just trigger the 'intention' with a light tap on the throttle. Giving a throttle input gave a clear command I was intending to accelerate, would pull off smoothly with any acceleration rate.

I look at it this way, remember the AT is reactive, needs commands. Some drivers are too erratic, "on-off" drivers, are giving mixed inputs. To get the smoothest drive, give clear and precise instructions.

[Wills2]

Originally Posted by HighlandPete

What you illustrate does indicate it is directly influenced by real time inputs. The fact it is repeatable in the same conditions, suggests nothing in particular may be wrong with the transmission, more an interpretation of inputs.

I have always suspected this is a key reason some drivetrains have the issues reported. Whether it is tolerances of components, the combination of the build stack and sensitivities to driving environment and/or driver influences, limitations of software and computing power, is hard to quantify.

My 330d with the ZF 6-speed AT had one quirk, which I could repeat every day if I wanted to. Pulling out of my lane on a cold transmission, triggered if I almost needed to stop. Simply how I applied the throttle, either caused a jolt, or was a smooth pull away. As another poster has commented...



That's similar to what I would do, just trigger the 'intention' with a light tap on the throttle. Giving a throttle input gave a clear command I was intending to accelerate, would pull off smoothly with any acceleration rate.

I look at it this way, remember the AT is reactive, needs commands. Some drivers are too erratic, "on-off" drivers, are giving mixed inputs. To get the smoothest drive, give clear and precise instructions.

I'm not saying there was a fault, what I'm saying is these gearboxes are not perfect and do have limitations.

I've never driven a ZF6/8 or any automatic that didn't have it's own foibles and limitations whereby the gearbox for whatever reason doesn't respond to a command input in a timely manner.

[HighlandPete]

Originally Posted by Wills2

I'm not saying there was a fault, what I'm saying is these gearboxes are not perfect and do have limitations.

I've never driven a ZF6/8 or any automatic that didn't have it's own foibles and limitations whereby the gearbox for whatever reason doesn't respond to a command input in a timely manner.

Sorry if I came over that way, didn't mean to imply you were saying your comments implied a fault. Like I said for my 330d, it also had a 'quirk'.

I agree we will find the foibles and limitations. I'd say for the 8-speed, when driving in hilly terrain it does test the ability to interpret all the inputs.

What I do find, drivers can definitely influence how smooth AT works across varied situations. Same applies for DSG. Plus there is big difference with driving a faulty gearbox/software combination, than learning to drive an AT smoothly, to accommodate any limitations we find.

[Wills2]

Originally Posted by HighlandPete

Sorry if I came over that way, didn't mean to imply you were saying your comments implied a fault. Like I said for my 330d, it also had a 'quirk'.

I agree we will find the foibles and limitations. I'd say for the 8-speed, when driving in hilly terrain it does test the ability to interpret all the inputs.

What I do find, drivers can definitely influence how smooth AT works across varied situations. Same applies for DSG. Plus there is big difference with driving a faulty gearbox/software combination, than learning to drive an AT smoothly, to accommodate any limitations we find.

No issue I was just clarifying what I'd said.

I do find that no matter how many miles I drive (many, too many) no matter what the engine and gearbox combination (DCT or ZF) they will often put in a random occurrence, whether that be a hesitation/latent reaction/harsh shift down/clunk/judder etc.... and that's in addition to driver input induced issues.

Ghosts the in the machine.

[jinjur]

Super responses here guys.....certainly an education. It could very well be me given that I am used to the terrier like reactions of my Clio 172 daily steed.

If, using some of the suggestions, I can work around this with my driving habit then I most certainly will.

I do still think I will ask BMW to let me know what they think as the workshop manager is going to be taking the helm of ours for a bit to see what he thinks of the steering and I do trust him

Will report back of anything is deemed amiss.

Cheers
J

[TiredGeek]

AFAIK this sounds more like software getting caught out than a mechanical problem.....

If however you get a jump in revs then drive takes up with a thump after a delay then it's most likely a sticking valve in the gearbox, was common on the Volvo's I've just left.
FYI, the easiest way to fix or improve that was to do a couple of gearbox oil changes a thousand miles apart.

[speedski]

Okay - so everyone who buys an AUC should be made to reset the throttle. Mine reset has absolutely transformed the car - no weird mid bend shifting, no notable travel without response. The lag has gone and I am only annoyed that its taken me 6 months to discover it needed it.

Really pleased, now off to thank those who suggested it!

[SkyJawa]

[stefan4]

Originally Posted by speedski

Okay - so everyone who buys an AUC should be made to reset the throttle. Mine reset has absolutely transformed the car - no weird mid bend shifting, no notable travel without response. The lag has gone and I am only annoyed that its taken me 6 months to discover it needed it.

Really pleased, now off to thank those who suggested it!

brilliant!

[jinjur]

That is good news Speed..........so my question is, if i do the pedal reset, am i going to make a shit of my car?

I had always assumed that an AUC BMW would have had everything reset before we got it.......my car was almost like a factory reset had been done to iDrive etc. Perhaps that doesn't go as far as these pedal settings etc

Thoughts?

J

[speedski]

Originally Posted by jinjur

That is good news Speed..........so my question is, if i do the pedal reset, am i going to make a shit of my car?

I had always assumed that an AUC BMW would have had everything reset before we got it.......my car was almost like a factory reset had been done to iDrive etc. Perhaps that doesn't go as far as these pedal settings etc

Thoughts?

J

In my case the car was reset, I highly doubt the throttle was though - they had their driver deliver the car to me - but instantly I could tell something simply wasn't right - it was just so vague compared to the sport 520D box I had just come from.

If you are happy with how it is then leave it be - it seems to learn early and not change (I have done 6k in it and it wasn't any different from the first mile I drove it).

Now though, much happier