M4 OPF/No pops and bang?

[MG-M4]

Hey guys,

So I’ve been messing around with my M4, a 2020 OPF model. I set it up exactly like my old 2018 in terms of exhaust, M performance + akrapovic downpipes yet it is still considerably quieter than my old car.

On top of that, it seems to have the "bmw fart" coded out or something. Nothing happens when I lift off the throttle afyer heavily acceleration.

I coded out both the downpipes and OPF but that didn’t do much honestly. Is there anything I can do to improve the sound and bring back that loud bang?

I’m quite disheartened by the sound of the new car, seems stupid to me that BMW would make it purposefully quieter.

[maddmatth]

You'll need to flash a tune. Look at MHD or Bootmod3.

[hellokitty]

Was the exhaust you put on the 2020 model brand new?

You might need to drive it a few thousand miles before it will get louder if the exhaust is brand new.

It took me like 5000 miles of driving before it really sounded good… the breakdown of the exhaust packing material as well as carbon coating the interior of the piping made it deeper, refined and louder over time.

[Dang3r]

The OPF is definitely more quieter than the non-OPF but you shouldnt consider to flash the boot mod3, the burbles and flash-bangs could damage the cats.
At least: No one buys a M4 just for showing off with noise, aint?

[maddmatth]

Originally Posted by Dang3r

The OPF is definitely more quieter than the non-OPF but you shouldnt consider to flash the boot mod3, the burbles and flash-bangs could damage the cats.
At least: No one buys a M4 just for showing off with noise, aint?

He has downpipes and he mentioned coding out the OPF so that is gone too.

Also, burbles are a stock feature on the M4 Comp (version without OPF only I guess) so it's fine for cats.

[EricP3]

Is it possible the valves are stuck closed?

[MG-M4]

Thanks for your replies guys. I actually do have burbles, which to be honest I don’t always like. My car is a ZCP. They happen when I downshift. What I’m talking about is that loud "bang" that happens when you release throttle at higher RPMs.

My entire set up is exactly the same as my old car. I just took the parts right off the old one so it’s definitely not a break in issue. I’m closing in on 10,000km with the new car and there is no trace of that loud "bang" when releasing throttle.

On top of that I can’t really hear a difference on start up anymore when changing from efficient to sport plus. I used to be able to hear the valves open and the sound change.

I’ll check to see if it’s a valve problem even though I doubt it.

[Billy_BMW]

The OPF S55 cars do not have the loud chainsaw bark/fart noise at throttle lift. It’s been tuned out from factory for sound reasons and as far as I’m aware, none of the OTS Bootmod3 maps have this added for OPF cars.

If you’ve had a pre-OPF car, you’ll know it’s a pretty violent sound. I’m currently working with a tuner (Cary Jordan), to try and add this sound back to my OPF M2C, but so far, no luck.

I do know however that the MHD CS tune has this sound and I’ve heard it on OPF-equipped M2C’s, so it’s definitely possible to add it - it’s just a software limitation and finding a competent and experienced tuner to add it.

Which software are you tuning with?

[Dang3r]

Originally Posted by maddmatth

He has downpipes and he mentioned coding out the OPF so that is gone too.

Also, burbles are a stock feature on the M4 Comp (version without OPF only I guess) so it's fine for cats.

I own a M4CP non-OPF and know that. As long as you dont flashmod the SW, the cats are fine with it but I wont overdue it.
I had overread the downpipes, my bad.
His Akra only for non-OPF works just, because he had deleted the OPF, but nevertheless, you wont achieve a sound like before no matter what you do.

[MG-M4]

Originally Posted by Billy_BMW

The OPF S55 cars do not have the loud chainsaw bark/fart noise at throttle lift. It’s been tuned out from factory for sound reasons and as far as I’m aware, none of the OTS Bootmod3 maps have this added for OPF cars.

If you’ve had a pre-OPF car, you’ll know it’s a pretty violent sound. I’m currently working with a tuner (Cary Jordan), to try and add this sound back to my OPF M2C, but so far, no luck.

I do know however that the MHD CS tune has this sound and I’ve heard it on OPF-equipped M2C’s, so it’s definitely possible to add it - it’s just a software limitation and finding a competent and experienced tuner to add it.

Which software are you tuning with?

Jesus man, I’ve loved BMW for years but they’re making it harder and harder... I understand having to equip the cars with that damn filter but why on earth would they go out of their way to tune out that sound.

I’m not sure I’m running any software in particular, I simply had my friend who runs a shop tune it out. I’ll ask what he used.

If you don’t mind me asking, why don’t you simply use the MHD tune? Is there some issues with it I should know about before looking into it?

[swagon]

I think on OPF cars, the valves open for a tiny bit for the start-up roar, then close again since it always defaults to efficient mode. Valves should open in sport/sport plus at idle when you give it some gas. On later cars, the trick for opening valves before/during cold start was made impossible, post 2017/8, I think? Works on my 2016 during the cold start sequence.

That "farting" noise is the function of the standard anti-lag system in sport and sport plus. If your valves don't open, then I guess you can't hear it at all and for the OPF cars, they've perhaps got rid of some things for noise and particle emissions.

[Billy_BMW]

Originally Posted by MG-M4

Jesus man, I’ve loved BMW for years but they’re making it harder and harder... I understand having to equip the cars with that damn filter but why on earth would they go out of their way to tune out that sound.

I’m not sure I’m running any software in particular, I simply had my friend who runs a shop tune it out. I’ll ask what he used.

If you don’t mind me asking, why don’t you simply use the MHD tune? Is there some issues with it I should know about before looking into it?

Believe me, it was very frustrating as my brother had an F80 CS and if you’ve heard how violent it can sound, the OPF cars sound lame in comparison! Hence why I’ve gone down the custom software route to try and map that sound back in.

It’s not just the sound at throttle lift, but also when you’re drifting and bouncing off redline - it’s like a rev-cut sound, whereas the OPF cars sound like any normal BMW with a soft limiter.

I went with bootmod3 and already invested in it before finding out that the MHD CS map has it, but not their Stage 1 or GTS maps. As I’m on stage 1, it would be hard to go back to ‘only 460hp’. But that sound is very aggressive!

Hopefully that CaryJ can work some magic. It’s purely software-related a just needs magician to track down the ECU tables and copy them over. I’m still waiting though.

[Billy_BMW]

Originally Posted by swagon

I think on OPF cars, the valves open for a tiny bit for the start-up roar, then close again since it always defaults to efficient mode. Valves should open in sport/sport plus at idle when you give it some gas. On later cars, the trick for opening valves before/during cold start was made impossible, post 2017/8, I think? Works on my 2016 during the cold start sequence.

That "farting" noise is the function of the standard anti-lag system in sport and sport plus. If your valves don't open, then I guess you can't hear it at all and for the OPF cars, they've perhaps got rid of some things for noise and particle emissions.

Definitely mapped out the anti-lag for OPF cars; they sound very lame!

[MG-M4]

Thank you for all your replies guys! I’m going to look into that MHD tune and try installing it this week. Can’t believe BMW has made it this hard to achieve any sort of proper sound.

My current set up with the downpipes barely sounds as loud as my old car when it only had the M Perf exhaust.

[MG-M4]

Originally Posted by velvet_F82

Here's my car:

March 2020 build, OPF, stock software. Only mod is an OPF-back exhaust system. Check the second video for th BMW "fart"

https://youtube.com/shorts/ko5giSNn5qs?feature=share

Wait, what the hell? How did you do that? I’m not sure what you mean by an OPF back exhaust system? How did you manage that when the software seems to be different? It sounds almost like my old car! I’ve attached a video.

https://youtube.com/shorts/OgVrRuXtHMg?feature=share

[MG-M4]

Originally Posted by velvet_F82

OPF-back means from the OPF all the way back to the rear of the car. I've attached a photo for you to understand. The stock exhaust is cut behind the OPF filters and there is no middle silencer.

The rest of the car is 100% stock. DME was never touched, no OBD flash tune was ever applied. Again, My car has build date March 2020 and is a European spec car (Switzerland).

Interesting. I’ve recently ordered a Fabspeed midpipe, do you think that would achieve the same thing as your exhaust system?

[MG-M4]

Originally Posted by velvet_F82

I'm not familiar with the Fabspeed midpipe, however your car should already be way louder than mine. Especially if you even have downpipes.

The M-Performance exhaust system should achieve exactly the same as my exhaust system, as both do not have a mid-silencer (M Perf has the H-pipe, but same effect).

How did you go about coding out the OPF's? Maybe something went wrong with the software?

I don’t think so honestly. I started out with only the M Perf exhaust on my newer car and that sounded just like my old car when it was completely stock ie VERY QUIET. Keep in mind I hadn’t done anything with the software at that point. I only recently installed the downpipes and coded them and the filters out.

This car has left me scratching my head to be honest. My BMW dealer says everything is fine exhaust wise yet the whole damn thing sounds ridiculously quiet, even with downpipes.

[MG-M4]

Originally Posted by velvet_F82

Shot in the dark but, do the exhaust valves open properly?

I just checked, no problem valve wise. Only thing I can think of at this point is when my dealer installed the m performance exhaust, the CEL lit up and they took it back in. They told me they upgraded the software and changed it from EU5 to EU6. Not too sure how they did that but I did notice that the sound got even quieter after that.

[MG-M4]

Would flashing the car back to stock then re-coding the opf and downpipes make any difference? Since the dealer seems to have messed with the software when getting rid of the CEL?