[22andcounting]

The engineer recommended I swap fuel for a couple of tanks, it having run a pure diet of Shell, and as no fuel burns exactly the same, the ERG thresholds would be 'adjusted' slightly by the engine, swapped to BP last week and still the same. Its a really odd on this one, I might be imagining it but I think its worse when its raining/very damp outside - but I might just be grasping at straws

[22andcounting]

So got the car back today. Problem not resolved, as expected, but lots of data collected from the car while it was 'trembling' , so hopefully BMW can see what's going on. The technician who worked on my car said he can feel the same symptoms in two other cars he has driven this week, one a dealership car, one a customer car, both 520d Auto's - looks like its a common problem people.

[HighlandPete]

I do still wonder if it is an emissions strategy of some sort.

HighlandPete

[deejaygee]

Originally Posted by 22andcounting

So got the car back today. Problem not resolved, as expected, but lots of data collected from the car while it was 'trembling' , so hopefully BMW can see what's going on. The technician who worked on my car said he can feel the same symptoms in two other cars he has driven this week, one a dealership car, one a customer car, both 520d Auto's - looks like its a common problem people.

.

This must be recent though as mine sept 10 build is perfect. Really don't want a service in case they update software and ruin my car!!!

[Krill]

Could somebody please post their PUMA number here? I´m planning to talk to my dealer about this and it would help a lot if I had the PUMA ready beforehand. Thanks in advance!

[22andcounting]

Originally Posted by Krill

Could somebody please post their PUMA number here? I´m planning to talk to my dealer about this and it would help a lot if I had the PUMA ready beforehand. Thanks in advance!

the PUMA number is specific to a car, the dealership should raise a PUMA for your car, the more PUMA's the more urgently BMW will address the problem.

[22andcounting]

Originally Posted by HighlandPete

I do still wonder if it is an emissions strategy of some sort.

HighlandPete

I am inclined to think its more a fuelling issue than a gearbox one - purely because of how quickly the hesitations follow each other, I cant believe the gearbox could respond so quickly. It feels for all the world like a misfire on a 6 or 8 cylinder, more subtle than a misfire on a 4 would be, I'm with you highlandpete, I think its a quirk in the fuelling at those revs and under a certain engine load.

[HighlandPete]

Originally Posted by 22andcounting

I am inclined to think its more a fuelling issue than a gearbox one - purely because of how quickly the hesitations follow each other, I cant believe the gearbox could respond so quickly. It feels for all the world like a misfire on a 6 or 8 cylinder, more subtle than a misfire on a 4 would be, I'm with you highlandpete, I think its a quirk in the fuelling at those revs and under a certain engine load.

It makes more sense for it to be an engine issue than gearbox. It also happens on other manufacturer's engines, and coupled to manual boxes as well. I'm minded that some of the petrol engine gearbox jerkiness that is reported is also the engine, rather than the gearbox. Some have had adaptions changed, or returned to default. I'm not too sure what some have had done in reality, perhaps no more than the throttle adaption and that soon returns to user influenced imput values, hence the problem returns within days.

Cars are getting too complex and these issues are bound to throw up in some examples, IMO. Geting to the source of the problem is the difficult issue.

As a side issue, I had problems with my HVAC system in the E91, to cut a long story short, BMW collected data with a logger and passed it back to the designers of the system for comment. Turned out it was working normally, but my conditions up here in the Highlands were pushing the boundaries of the design and I'd keep getting what appeared to be a glitch. The design was much too clever for its own good, and as a user I'd have to manually override the auto function if I wanted to bypass the "fault" (read... limitation for rapidly changing humidity levels, in the design).

HighlandPete

[Z4C_luvver]

So let's rule out gearbox, as it's happening on MT's and AT's. Who here thinks it's happening at the engine, and who thinks it's happening at the brakes?

It certainly feels to me like it's happening at the engine (could be ignition or fuel), but, could it be the brakes, ie an ABS/TC fault??? Could it even be the hill 'hold' function going a bit nutty?

[Krill]

Originally Posted by 22andcounting

the PUMA number is specific to a car, the dealership should raise a PUMA for your car, the more PUMA's the more urgently BMW will address the problem.

Ok, but wouldn´t giving the techs an already registered PUMA give them a push in the right direction? Just my 2 cents...

[HighlandPete]

Originally Posted by 5er_luvver

So let's rule out gearbox, as it's happening on MT's and AT's. Who here thinks it's happening at the engine, and who thinks it's happening at the brakes?

It certainly feels to me like it's happening at the engine (could be ignition or fuel), but, could it be the brakes, ie an ABS/TC fault??? Could it even be the hill 'hold' function going a bit nutty?

Is there any reason/evidence to suspect an ABS/TC fault? My background includes a 'trouble shooting' engineering environment, so I'd never rule anything out.

As has been said, there are a lot of factors which could cause a slight hesitation/stumble at an rpm/load. Let's hope the data shows where this is occuring, be it turbo actuation, swirl control, fuelling, EGR or some sort of mix that overlaps. Or something else, completely different.

HighlandPete

[Z4C_luvver]

Originally Posted by HighlandPete

Is there any reason/evidence to suspect an ABS/TC fault? My background includes a 'trouble shooting' engineering environment, so I'd never rule anything out.

As has been said, there are a lot of factors which could cause a slight hesitation/stumble at an rpm/load. Let's hope the data shows where this is occuring, be it turbo actuation, swirl control, fuelling, EGR or some sort of mix that overlaps. Or something else, completely different.

HighlandPete

My thoughts along the ABS/TC line were whether the hill hold function (seeing as this occurs on inclines mostly) was faulting somewhere, sending false readings to the ABS module and grabbing the brakes. As mentioned, it feels to me like it would be fuel/ignition related, but I too come from an Engineering background (including 6 sigma) and have learnt to not make too many assumptions at the beginning. I felt the trannys could be ruled out because it's doubtful they would share any componentry. But... having said that, I may stand corrected, as they may well share sender units or the like.

Anyway, it's just my 2 cents/pence worth.

I'm very much looking forward to the outcome of this.

[22andcounting]

This burgeoning brake theory is actually very interesting. I first described the problem to the techs that it felt just like the rear brakes were being touched on and off quickly as th car appeared to slow slightly and it felt like the sensation was coming from the rear of the car. I did ask them to look at the rear brakes as they do Groan slightly if I have auto-hold activated just before the car comes to a halt and auto hold takes hold of the car. And just now they groaned as I braked very gently at a down hill t-junction, just before the car came to a stop. Gonna pass on this theory to the dealership, thanks guys

[22andcounting]

So the investigation is now moving literally to the back of the car and a potential fault with the dynamic traction control an stability management, views are it might be a faulty sensor causing the dtc to cut in momentarily and brake a wheel in error. I certainly hav a rear brake issue as the nearside rear 'groans' when I brake gently to a near stop on down hill junctions just before the car comes to a halt.

[HighlandPete]

I'm understanding and following the possible brake intervention 'thinking', hope this leads to some progress.

Is the investigation spurred on by the collected data?

HighlandPete

[Z4C_luvver]

Originally Posted by 22andcounting

So the investigation is now moving literally to the back of the car and a potential fault with the dynamic traction control an stability management, views are it might be a faulty sensor causing the dtc to cut in momentarily and brake a wheel in error. I certainly hav a rear brake issue as the nearside rear 'groans' when I brake gently to a near stop on down hill junctions just before the car comes to a halt.

22, are you saying that BMW are doing this 'rear' investigation?

[22andcounting]

Originally Posted by 5er_luvver

22, are you saying that BMW are doing this 'rear' investigation?

Yep, taking car up on Thursday

[BMWMB]

My 530d xDrive does it too, but at lower speeds (40/50mph). My car has now 4500km's and i'm experiencing it less. Maybe it will disappear after a few more km's.

[Z4C_luvver]

Looking forward to the outcome!! Good luck!!

[martin mustang]

No longer happening on my one, even on highways.

[22andcounting]

Yesterday, didnt do it once on way to Slough, 132. Miles, coming home, worse it's ever been, 74mph on hills jerk jerk jerk, counted 21 consecutive hesitations on one hill, much more pronounced than before. Car now covered 4200k miles going in tomorrow they can keep the thing til they fix it!

[Z4C_luvver]

Originally Posted by 22andcounting

Yesterday, didnt do it once on way to Slough, 132. Miles, coming home, worse it's ever been, 74mph on hills jerk jerk jerk, counted 21 consecutive hesitations on one hill, much more pronounced than before. Car now covered 4200k miles going in tomorrow they can keep the thing til they fix it!

Sorry to read that 22. Let's hope it's sorted out soon. Mine was bad this morning too.

I think I read somewhere that when the cruise control uses it's active braking function, the brake lights come on (sounds logical)?

But I wonder if someone were to drive behind you on an incline, and if the problem was brake related, whether the brake lights would be flickering?