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      12-18-2019, 04:36 AM   #1
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Exclamation BMW M2 Anti-Lag braaap sound after lifting the throttle (N55 engines)

Hello everyone,
I have been thinking about what makes this "braaap" sound after lifting the throttle in M2 (non competition). It is done by the wastegate right?

Could I possibly implement it on M235i/M240i by purchasing DME/turbo&exhaust manifold from M2 and putting it on 235i/240i?

The sound I'm looking for:


It sounds like anti lag system, Just to be clear, I'm not looking for other burble tune.

Quote:
Originally Posted by Jeff@TopGearSolutions View Post
It sounds like fuel over-run. Basically unburnt fuel in the exhaust, exploding.
Well, it's not a simple burble tune. As I said, it more like ALS.

Here's a quote from @Andrew

Quote:
So basically the answer is yes it is possible, but technically, as of now I don't believe there is any off the shelf options to achieve this, It would need to be hard flashed not something simply coded, a retrofit of m2 n55 engine parameters would possibly be the answer, the hardware is all there between the two cars, flash tune manufactures are focused on fuel dumping for flame maps or "ak47" burble and not so much the OEM M throttle lift, I enjoy the sound as well and was interested in retrofitting

Basically BMW is using the DME to controlling fuel sending more when the throttle goes to close in order to keep the turbo/turbos spooling in order to mitigate lag thats what is going on from my understanding, the m2 has pretty much the same engine as the m235, there are differences but not enough to make an engine parameter from one incompatible with another as far as I know

I ended up selling my m235i and now have an f80 so I never continued to search for the answer to this, I would think it is possible to contact someone who creates DME flashes, such as bootmod3, in the parameter entries there must be a specific location that controls overrun, distinguishing the difference between the non m n55 and the m n55 and would be a simple addition as it already exist
So I'm wondering now if my local tuner could adopt M2 DME into m235i.
Used DME for M2 cost around ~1.2k I believe.




Quote:
Originally Posted by Darubba View Post
Nice video
With catless downpipe it sounds even better!


Quote:
Originally Posted by ChristosD View Post
i believe the difference on the limiter in sound between a m2 and normal n55 (235 etc) is that the m2 has a hard cut limiter that makes that aggressive braap noise. if you look at the m2 rev gauge when its on the limiter it bounces a lot more aggressively then a 235.
I don't think that's the case here.

Quote:
Originally Posted by ngl View Post
My 228i does a similar sound on upshifts after muffler delete. Not as pronounced though. The M2 has a more aggressive exhaust then the normal 2 series, so it makes sense.
What you are saying is a standard sound when you are upshifting.

Tech Part:
Quote:
Originally Posted by Boss330 View Post
With valvetronic, you can have better control of valves (I guess?). For instance creating a "blow through" situation where the injected fuel is ignited but the combustion pressure isn't trapped inside the combustion chamber but released through the exhaust valves (intake valves must be closed during this stage to avoid the pressure escaping to the intake manifold) and thereby spinning the turbos. Sort of like igniting fuel in a container with a small opening, creating a "jet stream" of hot air (exhaust). That "jet stream" will keep the turbos spinning at a high rpm (stated to be around 100.000rpm!!!). Since the combustion pressure is bled out through the exhaust valves, engine braking shouldn't be adversely affected perhaps?

And I also believe that this "jet stream" will be able to sustain a certain boost pressure even under deceleration. At least that would be beneficial in reducing lag, as otherwise the turbos will need time to raise pressure. With a "anti lag base pressure" of say 0.5bar, the engine would feel much more responsive and lag will be virtually non-existent.

For the cylinders that "participate" in the anti lag function this is how I imagine the system works:

Stage 1: Air enters combustion chamber (intake valves open, exhaust valves closed - intake stroke)
Stage 2: Air is compressed (intake and exhaust valves closed, creating engine braking - compression stroke)
Stage 3: Fuel is injected and spark is introduced (both intake and exhaust valves closed, or possibly starting to open exhaust valves here - combustion stroke)
Stage 4: Combustion starts and exhaust valves are opened to vent exhaust (intake valves closed, exhaust valves open - "exhaust stroke")

Stage 1-3 is equal to a normal 4-stroke combustion cycle
Stage 4 is different because the combustion energy isn't used to push down the piston, but to create a "jet stream" of exhaust gases to the turbos and spinning them.

Fuel injected in this "anti-lag" process is measured to create a combustion needed to spin the turbos, not the same amount of fuel needed to push down the piston in a normal 4-stroke cycle.


I'm pretty sure that emission and mileage data is at the normal settings for all cars on sale today.

Quote:
Originally Posted by CanAutM3 View Post
Good analysis .

I agree that, with this feature, it is possible to keep the car "on boost" with "closed throttles". To achieve this, the intake valves would need to open as little as possible on a few cylinders (while remaining closed on others) to just sustain the exhaust "jet stream" you mention. With the intake valves mostly closed there is very little air flow into the engine and the turbos do not need to produce much work to maintain boost. By precisely adjusting the bleed off valve and Valvtronic, the turbo speed and boost pressure can be maintained.

It is very similar to an old driving technique I learned in rally school. Left foot brake to slow the car down but keep the right foot on the throttle to keep the turbo spinning and on boost (I know, there are other reasons to left foot brake but this is also one of them )

Quote:
Originally Posted by CanAutM3 View Post
When abruptly lifting the throttle on the S55, "farting" noises can be heard. There is some wizardry happening in the engine system to keep the turbos spooled. It is most probably a combination of the waste-gates, Vanos and fuel injection that come into play to maintain high energy gases in the exhaust.

Quote:
Originally Posted by Boss330 View Post
As far as I know, very few production turbo engines employ anti lag by using an open throttle and injecting fuel. The S55 and Porsche 991 Turbo S has at least "cold blowing". That is, keeping the throttle/valvetronic open on the overrun so that the engine continues to pump air and spool the turbo. The 991 Turbo S only introduced this technology on the facelifted version going on the market this year.

Quote:
Originally Posted by ChristosD View Post
i genuinely think this is true sounds like a hard cut limiter i think they did this to make the m2 sound more aggressive as i cant see the performance benefit
That's completely something different. Hard cut limiter on 4500 RPM?
It's more like soft limiter but ALS (Anti-Lag System) kicks in and that's why you hear it.

Pretty much all M cars does this right now (maybe besides newest M5).
Definitely not a "hard cut limiter", even the thing with wastegate which @nioh_lbbm2 said is more realistic than hard cut limiter.




Make sure to analyze those two videos.

Quote:
Originally Posted by julienjj View Post
The shift ''farts'' are caused by the torque reduction during shift. Give the transmission a break to execute the upshift faster.

The throttle lift-off cylinder blanking last 2 seconds to keep the turbos spooled.

Since I discovered the eeprom is different I'm waiting to find a local M2 to read it from.

What i hope now is that the DSC in a non-M car can "talk" to the M dme program... since the M2 N55 use the same DSC unit as the M3&M4 and not like the M235i

Also that the automatic transmission in my car works the same (almost a given, since BMW tend to design their engine software to match virtually all transmission they make, DCT, 6MT, ZF...) but still a risk
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      12-18-2019, 10:04 AM   #2
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so,

I have a n55 F25 - I have MHD with my own custom DME tune. Nothing I have done to it would make the throttle burble different than stock.

I have xHP - flashed to stage 3 OTS

I noticed that I get these same noises when I am in DSC OFF mode (hold traction control off for like 4 seconds) which i believe is my equivalent of sport plus - I don't have the driver experience buttons (yet). I also think it's cool as shit.

I've found a few places in the DME logic where off-throttle characteristics are tuned. Here are two I've found that aren't in standard definitions, but they really only relate to load. I am working on trying to find the behaviour of each one...

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      12-18-2019, 10:30 AM   #3
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OP, reach out to Bob at stage FP (my tuner) he stated he could do it.
I want to, but I have other issues to deal with on my car.
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      12-26-2019, 05:32 AM   #4
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Red face

Quote:
Originally Posted by anjuna View Post
so,
I also think it's cool as shit.
The problem is that I don't own yet 235i/435i so I can't do anything by myself atm. I'm super interested in doing this. Like this is a pure game changer when it comes to exhaust sound.

Quote:
Originally Posted by AmuroRay View Post
OP, reach out to Bob at stage FP (my tuner) he stated he could do it.
I want to, but I have other issues to deal with on my car.
Alright, I'm going to message him, also I will let other people from 235i forums know about this thread. I know that there were few people interested in doing this too.
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      12-27-2019, 05:10 AM   #5
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      12-27-2019, 07:16 AM   #6
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Definitely interested in this.
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      12-27-2019, 09:58 AM   #7
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My F25 does this in pretty much all modes when you are on the throttle enough, on BM3 though. Burbles are set to OEM I think.
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      12-28-2019, 05:42 PM   #8
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Cool

Quote:
Originally Posted by doodlebro View Post
My F25 does this in pretty much all modes when you are on the throttle enough, on BM3 though. Burbles are set to OEM I think.
Already said it at the beginning, it's not a simple burble tune
It's more like ALS.


Hopefully AmuroRay can supply us with some news!
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      12-28-2019, 07:19 PM   #9
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Yea this isn’t related to burbles. I’m located down the road from Bob at Stage Fab, they put my downpipe on — if he can figure this out I’ll be having him tune mine as well.
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      12-29-2019, 05:04 AM   #10
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Quote:
Originally Posted by f20two View Post
Yea this isn’t related to burbles.
Exactly, please keep us updated with your tune

I still think you will need a DME from M2, look up for it at ebay.
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      12-30-2019, 10:23 AM   #11
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Quote:
Originally Posted by Thomas590 View Post
Already said it at the beginning, it's not a simple burble tune
It's more like ALS.


Hopefully AmuroRay can supply us with some news!
Quote:
Originally Posted by f20two View Post
Yea this isn’t related to burbles. I’m located down the road from Bob at Stage Fab, they put my downpipe on — if he can figure this out I’ll be having him tune mine as well.
I never said it was related to burbles...?

Imagine getting worked up because someone shares data that may help solve your question
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      12-31-2019, 04:07 AM   #12
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Quote:
Originally Posted by doodlebro View Post
I never said it was related to burbles...?
You said that your F25 is doing the same thing when you are on "throttle enough". You clearly didn't read my post about it, you went straight to comment section and replied.

Quote:
Originally Posted by doodlebro View Post
F25 does this in pretty much all modes when you are on the throttle enough
Alright, to sort this out. Your F25 aren't doing this thing in any modes. You can't get anything close to that with any current tune at the market.
No need to talk about it again, peace.

Quote:
Originally Posted by doodlebro View Post
Imagine getting worked up because someone shares data that may help solve your question
Yeah, fingers crossed


Also, for the small update.
@julienjj finally got to read an M2 DME last week. He will be trying to get it to work on his n55 soon.


The good sign is that you can have this sound even with manual transmission. Our cars are equipped with ZF AT instead of DCT, shouldn't be a problem to get this to work

Quote:
Originally Posted by julienjj View Post
The X5 M f85 has the antilag as well. That feature is independant of the transmission.
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      12-31-2019, 06:52 AM   #13
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Quote:
Originally Posted by Thomas590 View Post
You said that your F25 is doing the same thing when you are on "throttle enough". You clearly didn't read my post about it, you went straight to comment section and replied.


Alright, to sort this out. Your F25 aren't doing this thing in any modes. You can't get anything close to that with any current tune at the market.
No need to talk about it again, peace.


Yeah, fingers crossed


Also, for the small update.
@julienjj finally got to read an M2 DME last week. He will be trying to get it to work on his n55 soon.


The good sign is that you can have this sound even with manual transmission. Our cars are equipped with ZF AT instead of DCT, shouldn't be a problem to get this to work
My wife's f25 n55 does exactly what your describing... ass
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      01-01-2020, 10:21 AM   #14
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Quote:
Originally Posted by Phantom10R View Post
My wife's f25 n55 does exactly what your describing... ass
So you are saying that F25 N55 is doing this and M235i N55 not?
M235i has more aggressive setup (different car concept and purposes) and it's lacking this feature. But wait! Mid-size SUV/compact SUV has this feature by factory


Oh c'mon man, why you are trolling? Somebody already warned me about bunch of rednecks telling me it's a burble tune or their cars are doing it with OEM setup

That's how f25 sounds with catless downpipe, please tell me when it does it sound like I described in my first post? Like this is not funny anymore, you are lacking of attention or you need to make more post at the forums so you can feel better? Listen, you don't have to prove anything here, me and others a looking for a solution, to get the ALS for non M2 cars. I don't want to start trash talk thread, if you want to talk crap, please switch threads. We are here for one purpose, to get this done and share the knowledge with others. You are not contributing anything to this thread right now.



What's the point of replying here if you don't even know what you are talking about? None besides M cars are doing this kind of behavior. We are not talking about the sound while upshifting gears (this is stock/OEM sound).
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      01-01-2020, 12:29 PM   #15
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The wifes f25 isnt tuned and has stock downpipe.

And yep.. it does it. Ass.
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      01-02-2020, 01:53 AM   #16
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Talking

Quote:
Originally Posted by Phantom10R View Post
The wifes f25 isnt tuned and has stock downpipe.

And yep.. it does it. Ass.
Please record the sound and upload it to YT. Everyone wants to see/hear it
F25 with stock setup (catted downpipe) is doing the exact same sound just like M2 non competition? Give me a break!
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      01-02-2020, 03:25 PM   #17
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Look, if we are here for one purpose, calling eachother names doesn't help, ass.

and YES. the second video you linked at 0:30 is EXACTLY how my F25 sounds when in sport+ with xhp.

If you REALLY want me to prove it, I WILL and post a youtube video with it. I'll even get the whole car in the picture just to prove it.



EDIT - Also, reread your original post. I find it interesting that you're convinced that a sound comes from a "wastegate."

It has nothing to do with a wastegate. In fact, a wastegate has ZERO to do with a brap, fuel overrun, or anything related to this sound. It has to do with ignition timing, injection timing, and the likes. I find it interesting that you seem to be so god damn determined to prove your point without understanding the technical aspect to it. There's no need to even buy an M2 DME - I believe MHD produces a M2 map as the "stock" map to flash (well, for my F25 it does...)

In fact, provide me with the hardware code and I can probably produce a M2 bin. There is a repository out there with them in it.

Last edited by anjuna; 01-02-2020 at 04:13 PM..
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      01-02-2020, 03:42 PM   #18
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Quote:
Originally Posted by anjuna View Post
Look, if we are here for one purpose, calling eachother names doesn't help, ass.

and YES. the second video you linked at 0:30 is EXACTLY how my F25 sounds when in sport+ with xhp.

If you REALLY want me to prove it, I WILL and post a youtube video with it. I'll even get the whole car in the picture just to prove it.

this.
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      01-03-2020, 06:59 AM   #19
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Quote:
Originally Posted by anjuna View Post
If you REALLY want me to prove it
Yes, please prove it and show me that I was wrong.

This thread was taken from 2-series forums, that's why you have mixed content in the first post.


Quote:
Originally Posted by anjuna View Post
and YES. the second video you linked at 0:30 is EXACTLY how my F25 sounds when in sport+ with xhp.
Please link which one, from the first post or my latest response? Because if it's from the latest response



I'm super confused now, that's the OEM stock sound which any 35i is doing..
We are talking about complete different sound which is only available for M cars.
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      01-05-2020, 07:11 PM   #20
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Have you tried the BM3 Transmission Flash. It made the throttle blip more pronounced for me. Sounds like the first video you posted but better honestly. Could be because of the AWE. Not sure. F30 N55 fyi.
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      01-07-2020, 04:13 PM   #21
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Imagine being this difficult to people who are only trying to help.

Sheesh man, you seem to be bad at communication
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      01-14-2020, 01:07 AM   #22
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Maybe because he's tired of re-explaining what he's actually referring to in his parent post? I find it hilarious that some boomers are chiming in with their so - called 'data' that come from their expansive bmw engineering knowledge and understanding that they've obtained from driving their wives' x3s.
All of your attempts at 'helping' were conjecture and ultimately unrelated to the OP and comes off as annoying. Yet you still continue to speak even after OP shut you down. Instead, you should apologize for filling the thread with incorrect / impertinent posts?
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