[Jim23k]

Hi all,

Last summer I bought a 2016 340i M-Sport touring AUC, great spec and I love the car.

One thing that does concern me a bit though is a noise I can hear when the engine is under moderate to high load, say from approx 2k rpm with throttle > 50% open.

I don't know whether to describe it as clicking/ticking/chirping noise but it's certainly not a sound I was expecting to hear and is a little disappointing given how smooth I was expecting an i6 to be.

It's fairly subtle and doesn't seem to change pitch or tone with increasing revs or load. Probably best described as a sound like a crinkly sweet wrapper!

At higher engine revs it gets completely drowned out by the engine/exhaust note, but is clearly audible to me at lower RPM when put under load.

It's under manufacturers warranty until March and the remainder of the AUC warranty until June.

Had it in to the dealership for investigation and after an extended test drive they reported the sound was injector noise and was normal, however I don't recall hearing the sound from another 340i I test drove. Injector noise does sound reasonable given the pressure they operate at but I'm keen to get some thoughts from others who have the B58 engine and if this is a 'characteristic' or something more problematic.

I've tried various fuels ranging from 95-99 octane and this doesn't appear to make any difference.

Certainly isn't impacting economy or performance in any way!

Thanks all!

[richatha]

Hey Jim, can't help as with the noise issue as don't have it personally but noticed your in Yorkshire so if close to Leeds we could compare my engine noise to yours to see if there is an issue?

[Mustard3]

Hi Jim, I don't think this sound is uncommon on the B58. I've read posts that I think were describing the same sound over on babybmw in the past and it was suggested it was something to do with the wastegate, and nothing to worry about.

I get a quite faint noise under enthusiastic acceleration that I would describe as like someone rustling a bag of sweets in the cinema 3 rows back. I'm think I had it on the N55 engine in my 235.

I don't think it's unusual for the B58 and unless yours is particularly intrusive I wouldn't worry about it.

[chris-c]

Take open the bonet and list the engine cover.
It is even louder.

[Sasquartch]

The N20 engine in my 328i sounds fairly horrible especially at tickover.

Normal, caused by direct injection and can affect any modern BMW petrol engine including the 6's

It hasn't got any better or worse over the 35k miles I've done it's just a characteristic. The car runs fine. I like to convince myself it's slightly better with premium fuel but there's only a very slight difference.

I did hear one tale of someone affected by noisy injectors getting them changed under warranty, this cured the noise but only for a few days. Then, once the ECU adaptations had adapted, the noise was back.

I do know that some engines are quieter than others but exactly why I don't know

Probably not much you can do about it but nothing to worry about it either

[Jim23k]

Originally Posted by richatha

Hey Jim, can't help as with the noise issue as don't have it personally but noticed your in Yorkshire so if close to Leeds we could compare my engine noise to yours to see if there is an issue?

That's a very kind offer Rich - thank you! I may take you up on that sometime!

Originally Posted by Mustard3

Hi Jim, I don't think this sound is uncommon on the B58. I've read posts that I think were describing the same sound over on babybmw in the past and it was suggested it was something to do with the wastegate, and nothing to worry about.

I get a quite faint noise under enthusiastic acceleration that I would describe as like someone rustling a bag of sweets in the cinema 3 rows back. I'm think I had it on the N55 engine in my 235.

I don't think it's unusual for the B58 and unless yours is particularly intrusive I wouldn't worry about it.

Cheers Mustard - that's a great way to describe the noise! I wouldn't describe it was particularly intrusive either but I do notice it at times. Strange as on occasions I struggle to replicate it, but on others it's very clear to me. Think I must be hypersensitive to car noise! Wonder if the colder weather has exacerbated it somewhat as I don't recall hearing it over the summer!

Originally Posted by chris-c

Take open the bonet and list the engine cover.
It is even louder.

I know what you mean Chris, but the slight 'ticking' at idle doesn't offend me at all - perhaps because the engine is absolutely whisper quiet when ambling along and accelerating with gentle throttle application.

Originally Posted by Sasquartch

The N20 engine in my 328i sounds fairly horrible especially at tickover.

Normal, caused by direct injection and can affect any modern BMW petrol engine including the 6's

It hasn't got any better or worse over the 35k miles I've done it's just a characteristic. The car runs fine. I like to convince myself it's slightly better with premium fuel but there's only a very slight difference.

I did hear one tale of someone affected by noisy injectors getting them changed under warranty, this cured the noise but only for a few days. Then, once the ECU adaptations had adapted, the noise was back.

I do know that some engines are quieter than others but exactly why I don't know

Probably not much you can do about it but nothing to worry about it either

Thanks Sasquartch, there does appear to be quite a few mixed reports about this sort of noise from reading around! I think you've nailed it in that it's nothing to worry about given how well it goes and also how frugal it can be. I may get another opinion from a different dealership whilst it's still under warranty but I have until the summer. Interesting that someone had injectors replaced and the noise still came back! Eek!

What a great forum - thanks all!

[Jim23k]

Quick follow up to this - took it to a good independent specialist (Autohaus in York - very impressed actually) and we took it for a test drive.

From the passenger side I could barely hear it!

He said he suspected the sound was just the high pressure fuel system and was nothing to worry about.

[Mustard3]

Thanks for the update. One less thing to worry about!

[Jim23k]

Originally Posted by Mustard3

Thanks for the update. One less thing to worry about!

Agreed! On with enjoying the car