[gwf545]

I was in DS today creeping up to a stop sign and BANG! It felt like I got rear-ended by a truck, but there was nobody behind me. My wife was sure we had been hit. It was very unnsettling. I have had a recent S/W upodate due to CCC replacement and I think it is CIP 20.x I thought this slam problem was supposed to be eliminated with CIP 17.02. Has anyyone else had this happen recently? Did BMW regress the S/W or just never fix the original problem? BMW NA, are you out there?

[mixterk]

gwf545, on Feb 20 2006, 06:31 AM, said:

I was in DS today creeping up to a stop sign and BANG! It felt like I got rear-ended by a truck, but there was nobody behind me. My wife was sure we had been hit. It was very unnsettling. I have had a recent S/W upodate due to CCC replacement and I think it is CIP 20.x I thought this slam problem was supposed to be eliminated with CIP 17.02. Has anyyone else had this happen recently? Did BMW regress the S/W or just never fix the original problem? BMW NA, are you out there?

My dealer took my car to 20.01 to try and fix the shift lag from pulling away to the gear being input (it would snatch as the revs increased). Instead of an improvement it has become worse and more frequent. It seems 20.01 is a backward step

[gomac]

mixterk, on Feb 20 2006, 08:31 AM, said:

My dealer took my car to 20.01 to try and fix the shift lag from pulling away to the gear being input (it would snatch as the revs increased). Instead of an improvement it has become worse and more frequent. It seems 20.01 is a backward step

This unfortunate event has happened to my car recently as well. If memory serves me correctly the "slam" has happened under CIP 15, 19, and now 20. You would think they could fix it. This particular time I was looking down since the car did not start as I pressed the gas pedal. The RPMs went up to about 700 before the kick in the rear. I am not sure if it made it to 750 or 800 since the jolt was so violent. I just wonder if a class action suit like what happened with the Audi's is possible. I guess in their case they had a wrecked car and insured people to show what happened. Unless this happens with a BMW rep it is just our word

[spareone3]

Mine's in for this again today.. Talking to the dealer they tell me that the process of purely updating the software is not enough (info from BMW) and the adaptive box requires "re-training". To do this they need to run the car in top gear (above 70mph) and do a series of slow downs and slow accelerations, 10-15 cycles. This apparently then teaches the box to be more sensitive...! To be honest if correct this sounds like why people often experience an initial improvement after s/w upgrade. Then due to various driving styles the fault manifests itself again after time. All sounds like a real band-aid fix rather than getting to the root-cause.
As said, this is what he told me BMW Germany had instructed all dealers to do when upgrading software for transmission slam! Anybody else heard this..?

[Saudi_545i]

gwf545, on Feb 20 2006, 01:31 AM, said:

I was in DS today creeping up to a stop sign and BANG! It felt like I got rear-ended by a truck, but there was nobody behind me. My wife was sure we had been hit. It was very unnsettling. I have had a recent S/W upodate due to CCC replacement and I think it is CIP 20.x I thought this slam problem was supposed to be eliminated with CIP 17.02. Has anyyone else had this happen recently? Did BMW regress the S/W or just never fix the original problem? BMW NA, are you out there?

It happened to me before. I was making a U-turn and I also thought I was rear ended. I’m not sure if I was on the DS mode. It was scary, but not as scary as the faulty puncture message I got on i-drive when I was doing 130 miles/hour

[KAF]

This follows this thread
http://forums.e60.ne...showtopic=20994

But I may as well post here instead.

This morning I took my car out with an engineer from ZF (who make the transmission) heis seconded to BMW UK to troubleshoot transmission issues.

He connected up a diagnostic kit to the plug in the drivers footwell to monitor the tranny whilst I drove.

We were able to reproduce the 'slam' to order by slowing to about 3 mph gradually and then just before coming to a halt, accelerating fairly briskly.

Almost every time the revs went up and after a delay the car picked up the drive and shot forward.

We could also reproduce another behaviour. When going down a steep hill, causing acceleration due to gravity with foot off throttle, touch and release the brakes. The car downshifts 2 gears, giving high revs, then accelerate again and you get quite harsh upshifts.

His explanation of the 'slam' was as follows.
The transmission is working 'normally'. The shift point is set up with a stop/go system so that as you drive in traffic the car does not drop below 2nd gear. This enables a smooth progress without unnessecary shifts into 1st. The normal pick up with gentle acceleration is easily achieved in 2nd.

The consequence of this set up is that if you suddenly ask the car for high acceleration levels it detects that it cannot achieve this in 2nd and selects 1st with a consequent delay. This has been measured by ZF as about 0.75 seconds, though he accepted it often feels a lot longer.
I pointed out that when pulling out into traffic which is travelling at 50mph, on oncoming car travels at 75 feet per second, so 0.75 of a second delay is not good news.

The only solution to the issue is to reset the shift points so that the car always selects 1st when the speed drops, this however would mean a huge number of 1>2 > 1 shifts in stop start traffic giving a poor ride and the risk of harsh low speed shifts.

The problem is exacerbated in larger diesel engines due to the high torque and the slight turbo delay.

The same process is present in petrol engines but is felt much less due to the faster response of the engine to the throttle and the lower torque at lower revs. hence it is often viewed as a diesel only problem. The greater the torque the more noticeable the behaviour. This explains why the 530D and 545i and up raise complaints whilst the 520i and 525D seem less prone.

The only way to mitigate the issue is to select DS which forces selection of 1st at low speeds, but be aware that you will feel harsher 2>1 shifts in traffic.

Every 5 series 'suffers' as do Jaguars, Audi's and others but due to different driving styles and road environments, some drivers will notice it more than others. It is especially noticeable if you are a frequent user of roundabouts where you often approach at a very slow speed the accelerate without coming to a full halt.

The downhill behaviour is due to the software detecting acceleration whilst also detecting a braking signal. It interprets this as brake failure and, as a safety system, initiates downshifts to provide engine braking.

The bottom line is that currently there is no 'solution' to the 'slam' issue, there is no software update beyond 17.10 that will have any direct effect on the tranny behaviour, though he does not rule out that at some time in the future there may be changes. There is nothing currently on the radar.

I have made my point that I am very unhappy that a £40,000 car does not have a better matching of transmission with engine and that this will probably be my first and last BMW if that is the quality I get for this kind of money.

I will now hit every car review website I can find to ensure that potential buyers of BMW's are made aware of this problem and are prepared to live with it.

[spareone3]

That's by far best and most plausable explaination I've heard to date...Far from satisfactory as you rightly point out but I'd say it was accurate and certainly "hits the nail on ethe head" as far as I'm concerned!
Many thanks for the detail....

[blingo]

Thanks for the report Keith. Unfortunately it makes sense, but if BMW know it can't be fixed, why are they sending a ZF engineer to investigate reports?

It strikes me that with a diesel the 2>1 downshift is actually costing more lost time directly than just accelerating in second. I found with my E39 530D that the extra torque from a tuning box resulted in noticeably less downshifts and that had less power than a current 530d.

Can the downshift to first be eliminated unless the vehicle is stationary (i.e no kickdown from 2>1)?

Interesting that some people report not having the problem at all, can it be only the way they drive and not related to a change of spec.?

[KAF]

Only way of eliminating the downshift is to be more gentle with the right foot and bring on the gas in a more gradual manner, then the box will be happy to stay on 2nd, it is the sudden request for power that triggers the downshift.

Alternatively if you come to a junction with crossing traffic and think you might need to get out quick, slip it into DS, which I started to do some time ago.

[blingo]

Thinking about this again:

Quote

...if you suddenly ask the car for high acceleration levels it detects that it cannot achieve this in 2nd and selects 1st...

This is where the problem is, they don't seem to have allowed for the high torque engines which CAN achieve this but are slow to rev. Or perhaps they are doing it to protect their gearbox from this amount of torque.

[KAF]

blingo, on Feb 20 2006, 01:01 PM, said:

Thinking about this again:
This is where the problem is, they don't seem to have allowed for the high torque engines which CAN achieve this but are slow to rev. Or perhaps they are doing it to protect their gearbox from this amount of torque.

Depends how quick you want to get away. Even with the high torque of the 530D and up, it will still be quicker off the mark in 1st than in 2nd. Hence the change trigger to a heavy right boot.

The problem is, that the car is a chunk of tin, it is reactive to any stimuli you provde, it cannot anticipate what you are going to ask it to do in advance.

So it can either be set up to stay in 2nd at very low speeds, especially when it has detected a period of slow movement as in traffic, or when coming to a gradual stop, giving smoothness.

Or it can be set up to take first at these speeds in case you should want to give it the boot, then you get frequent and irritating 2>1.>2 shifts in traffic.

As the guy pointed out, if that's what you want then fine, it's called DS mode !

He has a point I suppose.

[blingo]

What I'm having trouble getting my head around is why this has appeared now. The previous 530d never did it with the five speed auto, you could slow down, accelerate AND kick down. It was also supposed to be a 'learning' gearbox.

In addition, if it is as described by the ZF engineer then every 530/535d auto, before or since v17, should have the same problem but they don't seem to. I drove a 530d demonstrator for a day before choosing mine and if it had done this I would have noticed for sure. Many people report that the problem 'appears', what the engineer describes would surely be intrinsic throughout.

Is this particular gearbox slow to engage first?
Is the torque sensing or kickdown mechanism different?

While everything that you have been told rings true, I still think think it is only half the story.

Does anyone have a DMS car with slam?

[KAF]

With a 6 speed box the ratio's of 1st and 2nd will be quite close, so using 2nd as a move oof gear will be reasonable.
With a 5 speed box the difference between 1st and 2nd might just be too big for this, hence it would normally change to first when coming to a halt.

The ZF guy offered me the opportunity to try out any 530, he guaranteed he could reproduce it with any car fitted with this gearbox. This does hold water bearing in mind the problems Jag owners have had with the same ZF box.

Until he showed me exactly how to reproduce the effects, I had great difficulty getting it to slam when I wanted to. The problem only came up occasionally, I would have been very unlikely to have noticed it on a one day drive. It is only when you have lived with a car for a number of weeks and have experienced it a few times that it hits you 'this cannot be right'.

[mixterk]

Keith Farrow, on Feb 20 2006, 02:49 PM, said:

With a 6 speed box the ratio's of 1st and 2nd will be quite close, so using 2nd as a move oof gear will be reasonable.
With a 5 speed box the difference between 1st and 2nd might just be too big for this, hence it would normally change to first when coming to a halt.

The ZF guy offered me the opportunity to try out any 530, he guaranteed he could reproduce it with any car fitted with this gearbox. This does hold water bearing in mind the problems Jag owners have had with the same ZF box.

Until he showed me exactly how to reproduce the effects, I had great difficulty getting it to slam when I wanted to. The problem only came up occasionally, I would have been very unlikely to have noticed it on a one day drive. It is only when you have lived with a car for a number of weeks and have experienced it a few times that it hits you 'this cannot be right'.

Fantastic description Keith, well done. By far the best and most accurate description to date, its exactly as I have found. The effect became apparrent only after living with the car for some time, and becuase i have lot of roundabouts to contend with in a short space of time and at lower speeds I'm really starting to see it happen more.

Intersting also to read about the shifting timings, since 20.01 the cahnges between 1st and second seem really stupid, had a passenger comment on the "seemingly high revs" when pulling away before it would change (in D mode). It all seems much worse since the so called upgrade

They want the car for 3 days now, I suspect thay are going to do the bollocks with the 15 cucles of running it above 70mph or whatever.

I'm not happy that a person who driving style maybe. lets say "demanding on the go peddle" is going to lose out....for christ sake thats why I bought the 535d in the first place.

Rant over...one for all and all for one. What are we going to buy with our compensation money and refunds!!!

[KAF]

mixterk, on Feb 20 2006, 07:22 PM, said:

What are we going to buy with our compensation money and refunds!!!

An MB?