[MERLIN335i]

Hi All,

E92 335i M-Sport (5K miles).

From day one I have experienced what I can best describe as "variable throttle response" let me explain.
I never get the same engine response for same throttle pedal input, press it "X" amount and it responds well, press it the same amount 100 metres further on and responds like a slug !

Just to clarify, I am not talking about the small variations experienced due to atmospherics, temperature etc. Has been back under warranty several times, (waste gate settings checked and adjusted) has never thrown a fault code so, standard answer, “no fault code recorded, so there is nothing wrong with your car sir”.

However after the area technical manager got involved, BMW UK suddenly decided to fit two new latest spec complete turbo assemblies (8mm Waste gate shafts), “to cure a possible conflict between the previously upgraded software (V34) and the older type turbos/actuators”.

£4500 worth of turbos/labour later (glad it was warranty !) and still exactly the same, BMW made it quite clear they would not be spending any more money on my car unless it records fault codes.

When I collected the car after new turbos fitted, I got them to give me a print-out of the data stored on the key, the car later went in for an early oil change (my decision) and again I got them to do a print-out of the key data.

When I checked the data, the car had covered 388 miles, yet the Rear Disc Pads had 1864 miles of additional wear on them !!!!!!!!!!! Yet the fronts had virtually no additional wear, consequently the rear pads are going to be worn out long, long before the fronts, given the braking bias to the front this must indicate that the DSC/DTC is working overtime. The recorded average speed over those 388 miles was 18.2mph, so can hardly be accused of pushing the car hard, surely the DSC/DTC should not be operating.

I had previously complained/commented to the dealer “ I have never seen so much brake dust on a set of wheels in my life, how come there is more on the rear than the front ?? ” Yes, you guessed it,
“no fault code recorded, so there is nothing wrong with your car sir”.

I have now resorted to driving with the DCS/DTC fully turned off, surprise, surprise, snappy consistent throttle response, minimal brake dust on the rear, just the odd “moment”, but having cut my teeth driving 3 Litre Capri’s in the wet, a bit of opposite lock is not a problem, however the tyre wear will be.

I assume for some reason the DSC/DTC system is far far to sensitive, and causing my problems, but
“no fault code recorded, so there is nothing wrong with your car sir”.

This problem has no gone on for 10 months, I hate the car , hence the low mileage.

No Fault Codes, No BMW buy back, If I sell it, I lose a fortune !

Any comments, theories, solutions welcome.

[marcel b]

the rearpads last about half the time of the front ones, at least that is my experience. DSC is really kicking in early and braking the backwheels, more even then you will notice, because of the missing LSD. Driving in DTC will be better as it allows more slip and more angle. But still. Fitting a LSD will probably be a good solution for you :-)

However still, I do not have the differences in throttle response, at least when I drive "analog". When really driving "digital", flooring it then yes, DSC is working overtime, especially now in winter. So I cannot imagine everything is all right.

[willhollin]

Which dealer have you been using?

[MERLIN335i]

Originally Posted by marcel b

the rearpads last about half the time of the front ones, at least that is my experience. DSC is really kicking in early and braking the backwheels, more even then you will notice, because of the missing LSD. Driving in DTC will be better as it allows more slip and more angle. But still. Fitting a LSD will probably be a good solution for you :-)

However still, I do not have the differences in throttle response, at least when I drive "analog". When really driving "digital", flooring it then yes, DSC is working overtime, especially now in winter. So I cannot imagine everything is all right.

Marcel,

Thanks for quick response, I should have said, it is obvious that the DSC/DTC is working, but very rarely see a warning light. 1864 miles of wear in 388 miles, with this low average speed, surely this must tell BMW there is a fault. I think the "bad throttle response" is actually the DCS/DTC working before it should !

[MERLIN335i]

Originally Posted by willhollin

Which dealer have you been using?

Will,
Thanks for response, Wayside - Milton Keynes.

[xenon]

I seem to remember reading somewhere - and I may be imagining this - that by a combination of button presses one can alter the sensitivity of the system. Or is that just the M5/M6?

[MERLIN335i]

Originally Posted by xenon

I seem to remember reading somewhere - and I may be imagining this - that by a combination of button presses one can alter the sensitivity of the system. Or is that just the M5/M6?

Ian,

Thanks for response, as far as I am aware it is either FULL DSC or DSC RESTRICTED & DTC ACTIVATED or BOTH OFF. Would be good if what you say is possible.

Anybody know about this, TONY ??

[marcel b]

Originally Posted by xenon

I seem to remember reading somewhere - and I may be imagining this - that by a combination of button presses one can alter the sensitivity of the system. Or is that just the M5/M6?

for sure he can, as it has the DCT function, but this should not be needed in normal daily driving. When I drive really gently, there is almost no wear on the front and the back, at least, there is no difference between front and back. The high wear and the big difference only occurs under spirited driving :-)

[marcel b]

Originally Posted by MERLIN335i

Marcel,

Thanks for quick response, I should have said, it is obvious that the DSC/DTC is working, but very rarely see a warning light. 1864 miles of wear in 388 miles, with this low average speed, surely this must tell BMW there is a fault. I think the "bad throttle response" is actually the DCS/DTC working before it should !

I agree! this seems very strange for me. Maybe you should bring it to another dealer to see what he says.

[MERLIN335i]

Originally Posted by marcel b

for sure he can, as it has the DCT function, but this should not be needed in normal daily driving. When I drive really gently, there is almost no wear on the front and the back, at least, there is no difference between front and back. The high wear and the big difference only occurs under spirited driving :-)

Marcel,

I think the problem is that the car thinks I am driving like a madman (spirited), but the low speed proves I am not. Maybe a wheel speed sensor fault ??????

[creepy coupe]

You could get yourself on a straight quiet road

Blue up the rear discs with either a fat marker pen or engineers blue.

Give it some beans and try replicate the symptoms, coast to a halt and see if the blue has come off.

Assuming you don't brake traction in a straight line, the DTC should keep quiet.

[MERLIN335i]

Originally Posted by creepy coupe

You could get yourself on a straight quiet road

Blue up the rear discs with either a fat marker pen or engineers blue.

Give it some beans and try replicate the symptoms, coast to a halt and see if the blue has come off.

Assuming you don't brake traction in a straight line, the DTC should keep quiet.

Hi,

Thanks for the response, the problem is that it is doing it when I don't give it any beans ! The excessive wear on the rear pads compared with the front ones over such low mileage proves (well to me at least) it is working when I drive it like an old granny 18.2 mph average (e.g. when I was running it in).

[MERLIN335i]

Originally Posted by marcel b

I agree! this seems very strange for me. Maybe you should bring it to another dealer to see what he says.

Marcel,
Here in the UK, BMW only pay their dealers for diagnostic work (under warranty) if they can prove it recorded a fault code, no fault code and the dealer doesn't get paid ! (except for obvious paint/cosmetic problems)

Every time my car was in the dealers it showed no fault codes, so my dealer had to absorb the cost of (46 hrs labour in total over several visits) as a gesture of good will, he did this only because he had made some money when I purchased the car.

If I take it to another dealer (Battersea or whoever) and as usual it shows no fault codes, the dealer will not be paid by BMW, therefore the dealer will not absorb the cost
as he has made no money from me, and I will be charged for the time @ £100+ per hour.

I do not see why I should pay, the car is under warranty that has only done 5000 miles
and the fault has existed from very early on.

[NFS]

Originally Posted by MERLIN335i

Hi,

Thanks for the response, the problem is that it is doing it when I don't give it any beans ! The excessive wear on the rear pads compared with the front ones over such low mileage proves (well to me at least) it is working when I drive it like an old granny 18.2 mph average (e.g. when I was running it in).

Whats the current estimated mileage for rear brake renewal?

(i.e. actual plus mileage to change).

This 'should' be more than 20k miles. If massively less then I think you may have a problem.

The throttle response on my 335i is much less direct than on my old 330i. Have you driven another 335i to see if it is any different to yours?

In terms of the DSC the light only comes on if there is an intervention lasting a couple of secs or more. So the rear brakes do tend to drag if you have a heavy right foot and you may not notice any flicker on the dash.

[MERLIN335i]

Originally Posted by NFS

Whats the current estimated mileage for rear brake renewal?

(i.e. actual plus mileage to change).

This 'should' be more than 20k miles. If massively less then I think you may have a problem.

The throttle response on my 335i is much less direct than on my old 330i. Have you driven another 335i to see if it is any different to yours?

In terms of the DSC the light only comes on if there is an intervention lasting a couple of secs or more. So the rear brakes do tend to drag if you have a heavy right foot and you may not notice any flicker on the dash.

Hi,
Thanks for taking the time.

Car has only done 5000 miles. (forgot to mention previously rear discs have wear ridge already !) not actually measured them, but quite noticable.

Rear Pads have 16,156 left.
Front Pads have 29,205 left.

I think the bad throttle response is because the system is cutting the power (for no good reason) and therefore you get a non reponsive throttle pedal.

BMW did provide another 335i for me to do "back to back" testing, but usual problem could not find a manual for ages, ended up with a manual, but it had been stood in a BMW UK compound for 8 months and had the "anti waste gate rattle/turbo lag" software version installed so this proved nothing about throttle response !

[NFS]

Originally Posted by MERLIN335i

Hi,
Thanks for taking the time.

Car has only done 5000 miles. (forgot to mention previously rear discs have wear ridge already !) not actually measured them, but quite noticable.

Rear Pads have 16,156 left.
Front Pads have 29,205 left.

I think the bad throttle response is because the system is cutting the power (for no good reason) and therefore you get a non reponsive throttle pedal.

BMW did provide another 335i for me to do "back to back" testing, but usual problem could not find a manual for ages, ended up with a manual, but it had been stood in a BMW UK compound for 8 months and had the "anti waste gate rattle/turbo lag" software version installed so this proved nothing about throttle response !

I think you may be right that DSC is the reason for the poor throttle response. The next question is to try to see if your DSC is any worse than normal.

I've done 500 miles and currently the rear brakes state 30k and the fronts 26k.

From experience I know this will change quite significantly and on my 330i The rear brakes lasted half as long as the fronts (about 20k miles, which is what your car is currently suggesting). I was suprised at this, but I'm certain it's because of the DSC+ system braking rear wheels for stability.

This is probably happening when cornering rather than accelerating or braking (essentially it's as if one of the brakes is gently trailing in most corners). If it's happening in the corners, then the average speed isn't going to be particularly relevant.

Just reading the about your experience with DTC on - your comment about tyre wear / dab of oppo etc makes me think you probably are cornering with 'enthusiasm'. I can also confirm that in my case the throttle response is more linear and the car more 'lively' with DTC on.

How hard to you have to be accelerating to experience the sluggish throttle response? Throttle at 25% / 50% / 75%?

Is it particularly apparent when accelerating out of corners?

[MERLIN335i]

Originally Posted by NFS

I think you may be right that DSC is the reason for the poor throttle response. The next question is to try to see if your DSC is any worse than normal.

I've done 500 miles and currently the rear brakes state 30k and the fronts 26k.

From experience I know this will change quite significantly and on my 330i The rear brakes lasted half as long as the fronts (about 20k miles, which is what your car is currently suggesting). I was suprised at this, but I'm certain it's because of the DSC+ system braking rear wheels for stability.

This is probably happening when cornering rather than accelerating or braking (essentially it's as if one of the brakes is gently trailing in most corners). If it's happening in the corners, then the average speed isn't going to be particularly relevant.

Just reading the about your experience with DTC on - your comment about tyre wear / dab of oppo etc makes me think you probably are cornering with 'enthusiasm'. I can also confirm that in my case the throttle response is more linear and the car more 'lively' with DTC on.

How hard to you have to be accelerating to experience the sluggish throttle response? Throttle at 25% / 50% / 75%?

Is it particularly apparent when accelerating out of corners?

I have experienced this problem from vitually day one of ownership, was even doing it when I was "running-in",(driving it like an old woman) as a result I do not trust the car, as you never know what throttle response you will get from one minute to the next. (one minute it goes like a scalded cat, the next a Fiesta on 3 cylinders).

As I said it is no "JOY" to drive (excuse the pun), because of this problem it has become just a mode of transport to get from A to B. I no longer bother to drive it "enthusiastically". Just to correct something you said (may be my fault) the only way I can get consistant thottle reponse/power is to turn the DSC/DTC COMPLETELY OFF(not half way), but obviously then without even trying too hard on greasy/wet roads you get into the opposite lock mode and therefore rapid tyre wear.

Problem occurs at 25% throttle and under, in a straight line, I don't push it in bends, as you need a predictable throttle response to corner hard.

Thanks once again for taking the time to answer.

[NFS]

Is it an auto or manual?

[MERLIN335i]

Originally Posted by NFS

Is it an auto or manual?

Manual.

[marcel b]

Originally Posted by MERLIN335i

I have experienced this problem from vitually day one of ownership, was even doing it when I was "running-in",(driving it like an old woman) as a result I do not trust the car, as you never know what throttle response you will get from one minute to the next. (one minute it goes like a scalded cat, the next a Fiesta on 3 cylinders).

As I said it is no "JOY" to drive (excuse the pun), because of this problem it has become just a mode of transport to get from A to B. I no longer bother to drive it "enthusiastically". Just to correct something you said (may be my fault) the only way I can get consistant thottle reponse/power is to turn the DSC/DTC COMPLETELY OFF(not half way), but obviously then without even trying too hard on greasy/wet roads you get into the opposite lock mode and therefore rapid tyre wear.

Problem occurs at 25% throttle and under, in a straight line, I don't push it in bends, as you need a predictable throttle response to corner hard.

Thanks once again for taking the time to answer.

based on this... there is for sure something wrong with your car. If a mechanic would drive it, he would for sure feel it. I once had a strange feeling in my former Z4M, brought it to the garage several times for it. Chief mechanic went for a drive with me so I could show him what I felt. They can plug a laptop in while driving to be able to see what DSC is doing. If you just bought a car there, they at least can have a mechanic have a drive with you! If not, isn't there a possibility to escalate this to BMW UK?
Sorry to hear all of this, this is for sure not what you had in mind buying a BMW. But believe me, as soon as this is fix, you will love it. Don't give up on her!

[HighlandPete]

What sort of road surfaces are you driving on? A lot of smooth hardtop? You mention low average speeds, but what sort of driving are you doing, stop start, lots of roundabouts? You also say the car is totally different with DSC totally switched off, again what sort of driving? From light to moderate, in comparison to light to moderate with DSC on.

I can't get my head around the throttle response bit and DSC being linked, if you drive lightly. DSC shouldn't even be getting a look in, in normal driving. Something is not adding up here.

HighlandPete

[NFS]

Originally Posted by HighlandPete

I can't get my head around the throttle response bit and DSC being linked, if you drive lightly. DSC shouldn't even be getting a look in, in normal driving. Something is not adding up here.

If it IS a problem with the DSC, then it should have been obvious to the road testing mechanic.