335i HPFP failure?

[Darlo74]

My 335i has developed an intermittent fault. It's happened twice in the last week. When accelerating hard at 50mph it's stared misfiring and the amber EML light has come on. It doesn't go into reduced power/limp mode. The lumpy ride continues until I come to stop and drop the revs and then it seems to correct itself and the EML goes out. It then drives fine. There are no problems at idle or when accelerating hard from a standstill.

At first I thought HPFP, anyone else suffered similar symptoms?

[ManOpener]

The symptoms are very similar to HPFP failure in various direct injection VW petrols (stutter/hesitation/misfire at high load) but injectors could cause similar symptoms. Do you have anything to read the ECU codes? That might help you establish a root cause.

[Smuler]

I had a 2009 335i and reading your post made me think injectors ; was the only thing which went wrong on mine so never had a HPFP problem .

I diagnosed with a 5£ OBD reader (maybe called ELM) bought on Amazon and the Android Ap I think torque pro.

[survivalist]

I’ve owned a N54 for three years. Based on your description it could be either HPFP or injectors. I’ve had both replaced at different times.

Both seemed to start failing under hard accerleration. In the case of the HPFP it would ‘recover’ but when it was the injectors it would require a switch off and on to get rid of the light.

For me, however, the fuel pump would cause misfires from a cold start - the injectors were only ever an issue under accerleration.

[royobannan]

Mine started doing that a few months ago. Was due a spark plug change at the time and the garage chap said to do that first and has never done it since!

[Darlo74]

Thanks for the replies guys - took it into BMW today, apparently the misfire was on cylinder 3 so changed the coil and spark plug and running fine now. Hope it's all fixed, will see how it runs over the next few weeks.