[shiner]

Hi all,
Got an issue with my 535D Auto. In traffic when I press the gas pedal there is a slight jerk/shudder. Taking foot off of gas in same traffic, likewise, slight shudder. I thought it was me but missus noticed it as well and thought it was my driving.... . Not a real bad "kangarooing" type of shudder but it is definitely there. Engine does not seem to be as smooth as it once did even when moving. No warning lights. No service is due and no other obvious issues but the engine seems not to be quite "right". Seems like the timing is not quite right or like in the old days when the spark was not advancing. It feels like that.

Booked it into BMW service on Friday. Car covered under warranty still so I asked it this would be covered. They said yes if it was a manufacturer defect. My worry is if they say it is not a defect but a dirty air hose or consumable and try to make me pay? I would not accept that if so.

[The Beast]

You sure it's the engine and not when the gearbox is shifting from 1st to 2nd and vice versa?

[shiner]

From complete stop and foot on brake pedal; press accelerator and it jerks slightly from pulling off. Whether this is because of the gearbox moving into gear causes this jerk motion or whether it is the engine itself I don't know. Does not do it between auto gear shifts once moving. Take foot off of gas when moving slowly in traffic and I get the jerking again.

Whether this is an engine or gearbox issue I don't know. What I know is that it is rough running compared to how it used to be. It never used to do this. Passengers have noticed it as well.

[Ronstein]

Originally Posted by shiner

From complete stop and foot on brake pedal; press accelerator and it jerks slightly from pulling off. Whether this is because of the gearbox moving into gear causes this jerk motion or whether it is the engine itself I don't know. Does not do it between auto gear shifts once moving. Take foot off of gas when moving slowly in traffic and I get the jerking again.

Whether this is an engine or gearbox issue I don't know. What I know is that it is rough running compared to how it used to be. It never used to do this. Passengers have noticed it as well.

A bit left-field, but could it be a problem with the auto handbrake?

[shiner]

If I just "ride" the automatic gearbox, i.e. just let my foot off the brake and let the car creep, it does not do it.

Does it without the auto handbrake being applied....

[shiner]

This issue throws up no error codes. However the BMW mechanic recognised the issue and it is the cooling system getting too hot in certain parts that the sensor does not "see" and so reports no issues. Yeah, as an engineer myself I find that one difficult too.... However, they changed part of the radiator and some piping and the issue has gone. Mine is not first five series they have seen with this issue and it can effect all diesel engine types.

[HighlandPete]

Originally Posted by shiner

This issue throws up no error codes. However the BMW mechanic recognised the issue and it is the cooling system getting too hot in certain parts that the sensor does not "see" and so reports no issues. Yeah, as an engineer myself I find that one difficult too.... However, they changed part of the radiator and some piping and the issue has gone. Mine is not first five series they have seen with this issue and it can effect all diesel engine types.

Do they mean problems with the EGR system, possibly changing the heat exchanger and associated parts? Incorrect EGR flows do cause issues like you describe.

EGR cooler, definitely been an issue with some recent 35d engines.

[shiner]

Yes, the EGR system, that was it. Had it changed out. Runs much better now. There were no fault codes or anything.

[shiner]

Still doing it. A rough pick up when pressing the gas pedal and a slight jerk when pedal released.
Back to BMW......