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2Addicts | BMW 2-Series forum Technical Topics N55 (M235i) Engine, Transmission, Exhaust, Tuning BMW M2 Anti-Lag braaap sound after lifting the throttle

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      10-15-2019, 12:50 PM   #23
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Quote:
Originally Posted by julienjj View Post
The BM3 m2 maps just transfer over the basic M2 parameters. The M2 use totally different software BUT the same hardware. Normally BMW protect those by FSC (Preventing you from flashing the 320i into a 328i) but the M2 DME is running an incompatible eeprom so it seems they didn't bother

Replacing the eeprom in the DME is not something that can be done by bootmod or by OBD at all.
So did it work
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      10-16-2019, 09:18 AM   #24
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Red face

Quote:
Originally Posted by julienjj View Post
The BM3 m2 maps just transfer over the basic M2 parameters. The M2 use totally different software BUT the same hardware. Normally BMW protect those by FSC (Preventing you from flashing the 320i into a 328i) but the M2 DME is running an incompatible eeprom so it seems they didn't bother

Replacing the eeprom in the DME is not something that can be done by bootmod or by OBD at all.
Thanks for explanation!


Quote:
Originally Posted by julienjj View Post
Not sure if it's because of this thread, but a customer came to me with this thing.

I'll try over the weekend to flash my N55 EWG with the M2 files for testing.
Keep us updated please
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      10-16-2019, 10:56 AM   #25
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I thought the farts were due to ignition cuts to help bleed off boost, vw/audi have done this sound for a long time when shifting their dcts
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      10-17-2019, 12:34 AM   #26
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Quote:
Originally Posted by glachhman3 View Post
I thought the farts were due to ignition cuts to help bleed off boost, vw/audi have done this sound for a long time when shifting their dcts
i also thought this but after watching the 2 videos above its anti lag for sure as this sound doesn't only happen on gear change but also in gear when you lift off the throttle. manuals and dct make this same noise.
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      10-18-2019, 02:31 PM   #27
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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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      10-20-2019, 04:56 AM   #28
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Talking

Quote:
Originally Posted by julienjj View Post
Since I discovered the eeprom is different I'm waiting to find a local M2 to read it from.
Where exactly do you live?

Quote:
Originally Posted by julienjj View Post
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
I see, well imagine if you could get this to work. $100k guarantee in the first month People would travel to you from different states just to get this feature.
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      10-23-2019, 08:16 AM   #29
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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
would there be hardware changes or could this be done over the air because im in if you can do this via remote login
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      10-23-2019, 01:53 PM   #30
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Can it be done?
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      10-25-2019, 03:03 PM   #31
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Hey guys, I spoke to Bob from Stage FP, and he stated that he believes he can do it. It’s who I currently have my custom tune from.
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      10-26-2019, 04:09 PM   #32
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Quote:
Originally Posted by AmuroRay View Post
Hey guys, I spoke to Bob from Stage FP, and he stated that he believes he can do it. It’s who I currently have my custom tune from.
Are you planning to do this? Let us know
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      10-29-2019, 06:22 AM   #33
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Yeah, I may!
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      10-31-2019, 04:38 AM   #34
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Talking

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Originally Posted by AmuroRay View Post
Yeah, I may!
I'm probably not the only one viewing this thread every day
Keep us updated please.
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      10-31-2019, 06:30 PM   #35
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Quote:
Originally Posted by Thomas590 View Post
I'm probably not the only one viewing this thread every day
Keep us updated please.

Alright, I’ll request it. But I have been waiting on fixing my HPFP first.
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      11-05-2019, 08:36 AM   #36
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Quote:
Originally Posted by AmuroRay View Post
Alright, I’ll request it. But I have been waiting on fixing my HPFP first.
would something like this run in tandem with a bootmod3 ots file or would you need a custom file to incorporate this?
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      11-06-2019, 07:44 AM   #37
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Quote:
Originally Posted by ChristosD View Post
would something like this run in tandem with a bootmod3 ots file or would you need a custom file to incorporate this?
You would likely need a custom tune.
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      11-15-2019, 03:58 AM   #38
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Hey, any updates?
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      11-18-2019, 01:23 PM   #39
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Quote:
Originally Posted by Thomas590 View Post
Hey, any updates?
LOL, I completely forgot about this - I'll shoot him an email today.
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      12-01-2019, 11:57 AM   #40
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Any update on this?
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      12-01-2019, 01:47 PM   #41
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Quote:
Originally Posted by Arc1703 View Post
Any update on this?
Same
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      12-18-2019, 04:32 AM   #42
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I think, I should go to F30/F32 forums and ask there about it.


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 )
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      12-26-2019, 05:27 AM   #43
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Quote:
Originally Posted by Arc1703 View Post
Any update on this?
If anyone is still interested in doing this, check out this thread https://f30.bimmerpost.com/forums/sh....php?t=1678930 in 3 series forums.
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      12-26-2019, 01:31 PM   #44
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Quote:
Originally Posted by Thomas590 View Post
If anyone is still interested in doing this, check out this thread https://f30.bimmerpost.com/forums/sh....php?t=1678930 in 3 series forums.
Yes
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