[Anthony1s]

Do they serve any functional purpose? Or is it sunburnt fuel added specifically to create the sounds?

Also, is there any way to disable them? I don't see an option to code it out with Carly. I'm not familiar with E-SYS and can't find the cheat sheet for it, at the moment. Can E-SYS disable them? If not, what about JB4 or Bootmod3?

[zenmaster]

This seems to be the reason: https://www.quora.com/Why-do-modern-...n-the-over-run


A "backfire" should not happen in normal stock vehicle operation, as that indicates an overly rich condition where fuel is hitting the exhaust.

[TT1351]

Hex has a tune that can eliminate the burbles if you want, or they have a tune that offers more pops and burbles then stock. With that said, on older cars it was something that would drive you crazy trying to fine the cause, exhaust leak or whatever.

[TampaF87]

This was done on purpose by the original BMW engineers. They are marketing a sports car, and with that comes all of the ambience associated with it. As you change the driving modes, you'll notice that it becomes more prominent. This is intentional to "enhance" the driving experience. It's caused by injector overrun after the throttle plate closes. This dumps un-ignited fuel into the exhaust which is then ignited by the heat of the exhaust. This causes backfires.

The only way to eliminate the factory burbles and backfires, is for a tune to override it, but that would put your warranty at risk. IMHO, it's not worth it to void your warranty to rid yourself of backfires, unless you plan on modding, in which case it's moot lol

[HODLM]

It's one of my favorite parts of driving the car. Not sure why you'd want to code it out.

[///M²]

You can drive in comfort mode all the time, that has no burbles.

[Anthony1s]

Originally Posted by HODLM

It's one of my favorite parts of driving the car. Not sure why you'd want to code it out.

Because if it's there solely for sound purposes, I think it's a waste of fuel. Also it draws more attention to me and my car than I'm comfortable with.

If it has a purpose, like making sure the turbo is always spooled, then I would be more inclined to leaving it.

[HODLM]

Originally Posted by Anthony1s

Because if it's there solely for sound purposes, I think it's a waste of fuel. Also it draws more attention to me and my car than I'm comfortable with.

If it has a purpose, like making sure the turbo is always spooled, then I would be more inclined to leaving it.

I totally get not wanting to draw extra attention (comfort mode), but this car is a (bad) attention magnet with or without the sounds. Every car with an after market exhaust wants to have a revving competition with me which is ludicrous and I refuse to partake, and everyone wants to race. The only times I engage in spirited driving is when I spot another M2 or M4 (soooo many M4's in Miami).

But at low speeds, windows down, I love hearing the pops!

[No Boost]

Originally Posted by zenmaster

This seems to be the reason: https://www.quora.com/Why-do-modern-...n-the-over-run


A "backfire" should not happen in normal stock vehicle operation, as that indicates an overly rich condition where fuel is hitting the exhaust.

I get the occasional backfire which occurs immediately after overrun under throttle liftoff. Is it possible the Dinan tune is running rich?

Regardless, I get a semi each and every time it happens

[Anthony1s]

Originally Posted by HODLM

I totally get not wanting to draw extra attention (comfort mode), but this car is a (bad) attention magnet with or without the sounds. Every car with an after market exhaust wants to have a revving competition with me which is ludicrous and I refuse to partake, and everyone wants to race. The only times I engage in spirited driving is when I spot another M2 or M4 (soooo many M4's in Miami).

But at low speeds, windows down, I love hearing the pops!

Ah yea, that's true. I can be in comfort mode when I want "less" attention or to not annoy my neighbors. The car already looks aggressive AF. And it's gonna be the nicest car in my whole city (there is one guy with a 2008 R8 otherwise) so I'm gonna get a lot of attention cause of that. Luckily most of the roads here are single lane, so there isn't a great chance of people pulling up next to me and wanting to race. I bought the car for myself, not to race anyone or show off. There are nice, wooded, windy roads 15-20mins away that get little to no traffic that I can enjoy my car on whenever I want.

[Aloha Joe]

Originally Posted by HODLM

But at low speeds, windows down, I love hearing the pops!

True, I do this in my office building parking lot (sport mode w/fabspeed) it definitely turns heads.

Having said that, there are times when I miss my 370z's smooth deceleration sounds from the exhaust. The VQ37 engine with an after market exhaust, is something very special.

[zenmaster]

Originally Posted by Stage IV

I get the occasional backfire which occurs immediately after overrun under throttle liftoff. Is it possible the Dinan tune is running rich?

Regardless, I get a semi each and every time it happens

Some tunes purposely run very rich to help reduce temps under load. Hey, it's a cheap fix. But if it's gonna backfire, it should at least shoot flames too. I think your cat won't last as long with exhaust combustion though.

[SeanWRT]

First of all, do not believe in this article. At least the theory doesn't apply to BMW turbocharged engines, all of which burble with a tune.
https://www.quora.com/Why-do-modern-...n-the-over-run

Secondly, overrun has nothing to do with rich or lean.

Running rich or lean is refered to as the AFR of the ignition in combustion stroke phase. Overrun is the ignition at exhaust stroke when timing valve is largely open and part of ignition takes place in exhaust manifold, which leads to incomplete fuel burn and leaves carbon residual on exhaust tail pipes, the source of misperception of running rich. As for functional purposes, depending on manifold design, overrun may or may not help keep the momentum of turbine on liftoff (to improve on/off turbo responsiveness). Mainly it's there for a little sports car drama - see those Huracans burble like crazy from factory without even a turbo?

@Stage IV
Dinan Elite for most applications runs factory rich, trying to be safe providing a warranty. The exceptions though are the 235/335/435 N55 Stage 4 big turbo. They run slightly leaner because piggyback is incapable of keeping up AFR with such boost (over stock). However, M2, in a higher tuning state from factory, doesn't get as much boost/power from STG4 than its N55 counterparts and is still programmed to be factory rich or somewhere close, which is way too rich and kills a bit power.

[F87_LCI]

Honestly, I got more "looks"/attention with my Laguna Seca Blue 335 than I do with the F87...the only guys (yes guys, girls don't care about cars unless it tells them what might be in your bank account!) that even seem to notice are guys in other M cars (3/4's) and the Golf GTI/R guys. Otherwise it seems most think it's just another blue BMW...except my neighbor who bitches about the noise (MPE + SportCat). I guess it all depends where you live.

But if you want to slide under the radar AND be fuel efficient...a Prius may have been a better choice for you.

[Anthony1s]

Originally Posted by LSB --> LBB

Honestly, I got more "looks"/attention with my Laguna Seca Blue 335 than I do with the F87...the only guys (yes guys, girls don't care about cars unless it tells them what might be in your bank account!) that even seem to notice are guys in other M cars (3/4's) and the Golf GTI/R guys. Otherwise it seems most think it's just another blue BMW...except my neighbor who bitches about the noise (MPE + SportCat). I guess it all depends where you live.

But if you want to slide under the radar AND be fuel efficient...a Prius may have been a better choice for you.

The Prius engine swap was heavily considered but I couldn't find a mechanic to do it

[grl.racr]

Originally Posted by LSB --> LBB

(yes guys, girls don't care about cars unless it tells them what might be in your bank account!)

not true