Soft misfire !

[mcbutler]

Hello all,
So - 35i - 42k miles - FSH - Full tank of momentum - 6 new BMW injectors 2000 miles ago.

I filled the car up this afternoon and my route home was via a fast (70mph) stretch of dual carriageway.
The slip road is a hard right loop followed by a left 'tweak' as you join the carriageway.

As I negotiated the right loop i put the DCT into sport (not the engine) and accelarated at around 85% throttle.
For a second I thought the rear tyres had lost grip (nothing new car is running a stage 2 MHD map with a fully mapped DCT) but then I realised that I had momentarily lost some - not all - power!
It was not a hard juddering misfire like an electrical failure or total fuel loss but a very 'soft' misfire for about 2 seconds max.
No dash lights or gong.

Carly on the car before I turned it off gave a 002DED error which means nothing really, its like a soft error prior to getting a warning light.

Screenshotted the error and its data which I will attach.

I have been running on E10 for two tank fulls as momentum was not available locally due to a split storage tank, Car was empty when i filled it with momentum today and I reckon it was getting its first taste of the momentum around the time of the error - not sure if that could be relevant.

So guys n gals - any ideas?????

[B21]

That error is when the DME finds a circuit that is consuming too much current in the given circumstances

Normally it’s associated with comfort access or Bluetooth type things not shutting down correctly when the car is parked

[Busterboo]

... The slip road is a hard right loop followed by a left 'tweak' as you join the carriageway.

As I negotiated the right loop i put the DCT into sport (not the engine) and accelerated at around 85% throttle.

1 Does this mean you pressed the accelerator 'hard and fast'? If it does, your "soft misfire" may be a common fault.
2 Since you drive the route often, testing this possibility will be easy, of course. Just try it again each day this week.
3 I suspect the "soft misfire" will happen again if you can replicate the same circumstances.
4 The solution is to avoid the "85% throttle".

[smorris_12]

I'd say traction control was having a mild intervention. Possibly a wheel skipped on a stone or slidey bit and, with the yaw sensor showing a lateral load, decided to do a Jeeves like intervention.

[Rockhopper]

Why did such a low mileage car need a new set of injectors? What’s the back story to that?

[smorris_12]

Aren't N54/55 injectors the prone-to-failure piezo ones?

[mcbutler]

... The slip road is a hard right loop followed by a left 'tweak' as you join the carriageway.

As I negotiated the right loop i put the DCT into sport (not the engine) and accelerated at around 85% throttle.

1 Does this mean you pressed the accelerator 'hard and fast'? If it does, your "soft misfire" may be a common fault.
2 Since you drive the route often, testing this possibility will be easy, of course. Just try it again each day this week.
3 I suspect the "soft misfire" will happen again if you can replicate the same circumstances.
4 The solution is to avoid the "85% throttle".

But if I avoid 85% throttle that means using 84% throttle max pernmanently!!

[mcbutler]

I'd say traction control was having a mild intervention. Possibly a wheel skipped on a stone or slidey bit and, with the yaw sensor showing a lateral load, decided to do a Jeeves like intervention.

Hi Scott, you know, I think you might be right with that idea, will bear this in mind....

[mcbutler]

Why did such a low mileage car need a new set of injectors? What’s the back story to that?

Well, its a 35 - in a word they are mechanically diabolical in regards to reliability but epic in regards to performance and tuning capacity.
I bought my car with 24k on it, FSH and annual BMW safety checks, hot garage stored and immaculate.
At 24k the car had already had a new HPFP, only 15k when that failed!!
My injectors were version 8 if I remember correctly, only one failed but the correct procedure is to replace all 6 at the latest version (12).
Car has also had a new radiator - iDrive display (£2600!!!!!!) - heater fan motor - Full DCT filter/oil/sumpand gasket job at 30k and its already weeping again (MOT last week picked that up) shite plastic sump pan is the reason, new rear lamp clusters. The coolant cap came off, luckily I was just arriving home so no damage done (hell of a mess though), countless diagnostic sessions and a few other bits n bobs.
Cam cover gasket has also started weeping, noted at MOT last week.

Its a love hate relationship lol

[mcbutler]

Aren't N54/55 injectors the prone-to-failure piezo ones?

Yep they are Piezo type

[Nictrix]

This sounds similar to what my car does on a few back roads around me and one every morning on the way to work.
Its not a fast bend, around 40 in a 60 limit, but you must slow for the bend. Half way around the bend when I press the go pedal it takes a second before the engine responds.
I have assumed that it is the car trying to keep me on the road as the steering is turned while asking for power.

[Busterboo]

But if I avoid 85% throttle that means using 84% throttle max pernmanently!!

It isn't the percentage, is it? It's how to get to the percentage. So, in simple terms, floor the pedal 100% and the car can't seamlessly deliver 100% of its power (of course). The E89 ain't a dragster.

In the situation you described, is it possible that the demand for too much power too quickly produced what you called a "soft misfire"?

Try it again and see.

[Miyli]

Are the ignition coils original or replaced sometime ?

[B21]

I suspect you had a transient misfire due to using lower rating fuel..MHD V10 stage 2+ is very aggressive in timing and already has many corrections at the best of times..

Misfire at around 85% is fairly typical..

As suggested how old are the coils? Supplier?

[B21]

But if I avoid 85% throttle that means using 84% throttle max pernmanently!!

It isn't the percentage, is it? It's how to get to the percentage. So, in simple terms, floor the pedal 100% and the car can't seamlessly deliver 100% of its power (of course). The E89 ain't a dragster.

In the situation you described, is it possible that the demand for too much power too quickly produced what you called a "soft misfire"?

Try it again and see.

N54 is fly be wire throttle…so irrespective of what position you put the accelerator pedal to it’s the DME that decides what to do…

What may have happened is if one wheel lost traction the e-diff may have intervened by firstly braking the spinning wheel then shutting power down briefly..