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[Denmark]

Hi All.

I dont have my laptop with me, but i was just wundering what that does in megatune, it´s the field right above "MAT retard enabled",
its in the "constant field" i seem to remember.

THanks,
Skassa

[fehrudi]

Hi,
I just found it on wiki:

Map Multiplication
What does the "Map Multiplication" in Megatune do exactly?
The pulsewidth would be multiplied "behind the scenes" with MAP. The fuel VE table often becomes "flat", but not always very flat especially at low kPa. VE value approx. 50% at 40 KPA, 200% at 250 kpa.

[rob@vems.co.uk]

From http://www.vems.hu/wiki/index.php?page=MembersPage%2FPhatBob%2FUserGuide
Under the section Configuring Air Metering.

Speed Density (MAP vs RPM)
For turbocharged and Normally Aspirated (NA) plenum based engines with mild camshaft timing, Speed Density provides the best metering solution.
Configuration
Set MAP Multiplication to: Enabled
Set max RPM for Alpha-N (rpm) to: 0
Set max RPM for Speed Density (rpm) to: 0

Alpha-N (TPS vs RPM)
Best suited to NA engines running independent throttle bodies (ITBs) where MAP readings are noisy and lack resolution.
Configuration
Set MAP Multiplication to: Disabled
Set max RPM for Alpha-N (rpm) to: 25500
Set max RPM for Speed Density (rpm) to: 25500

Alpha-N with Map multiplication
Turbocharged engines running ITBs are a special case, they have the same problems with MAP noise and resolution when off-boost, but need the MAP to be factored in at anything over atmospheric pressure.
Configuration
Set MAP Multiplication to: Enabled
Set max RPM for Alpha-N (rpm) to: At least 500 to 1000RPM below the max RPM for Speed Density (rpm)
Set max RPM for Speed Density (rpm) to: The RPM below where the Turbo starts to provide positive pressure.

Alpha-N/Speed Density blending
For NA engines with plenums that use more extreme camshafts and as a result have very noisy MAP signal at lower RPMS due to the valve overlap. Configuration values are dependent on the characteristics of the engine.
Configuration
Set MAP Multiplication to: Enabled
Set max RPM for Alpha-N (rpm) to the RPM point just above where the MAP signal starts to read cleanly.
Set max RPM for Speed Density (rpm) to a value just below the Alpha-N value.

Mass Air Flow (MAF)
In cases where a Mass Airflow Sensor is used to provide a Load value.
Configuration
Set MAP Multiplication to: Disabled
Set max RPM for Alpha-N (rpm) to: 0
Set max RPM for Speed Density (rpm) to: 0

[mads b (dk)]

From http://www.vems.hu/wiki/index.php?page=MembersPage%2FPhatBob%2FUserGuide
Under the section Configuring Air Metering.

Speed Density (MAP vs RPM)
For turbocharged and Normally Aspirated (NA) plenum based engines with mild camshaft timing, Speed Density provides the best metering solution.
Configuration
Set MAP Multiplication to: Enabled
Set max RPM for Alpha-N (rpm) to: 0
Set max RPM for Speed Density (rpm) to: 0

Alpha-N (TPS vs RPM)
Best suited to NA engines running independent throttle bodies (ITBs) where MAP readings are noisy and lack resolution.
Configuration
Set MAP Multiplication to: Disabled
Set max RPM for Alpha-N (rpm) to: 25500
Set max RPM for Speed Density (rpm) to: 25500

Alpha-N with Map multiplication
Turbocharged engines running ITBs are a special case, they have the same problems with MAP noise and resolution when off-boost, but need the MAP to be factored in at anything over atmospheric pressure.
Configuration
Set MAP Multiplication to: Enabled
Set max RPM for Alpha-N (rpm) to: At least 500 to 1000RPM below the max RPM for Speed Density (rpm)
Set max RPM for Speed Density (rpm) to: The RPM below where the Turbo starts to provide positive pressure.

Alpha-N/Speed Density blending
For NA engines with plenums that use more extreme camshafts and as a result have very noisy MAP signal at lower RPMS due to the valve overlap. Configuration values are dependent on the characteristics of the engine.
Configuration
Set MAP Multiplication to: Enabled
Set max RPM for Alpha-N (rpm) to the RPM point just above where the MAP signal starts to read cleanly.
Set max RPM for Speed Density (rpm) to a value just below the Alpha-N value.


Mass Air Flow (MAF)
In cases where a Mass Airflow Sensor is used to provide a Load value.
Configuration
Set MAP Multiplication to: Disabled
Set max RPM for Alpha-N (rpm) to: 0
Set max RPM for Speed Density (rpm) to: 0

hi i know this is an old post but, how do you set Alpha-N/Speed Density blending up in vemstune ?

i belive this old guide i for megatune

[GintsK]

IMHO it is not supported any more. Except if you do config switching maybe.
Alpha-N with MAP multiplication above atmospheric works fine.

Gints

[mads b (dk)]

did they remove that feature ? didtn it work ?

[GintsK]

Yes they removed. Since 1.1.77 or so: http://www.vems.hu/wiki/index.php?page=GenBoard%2FUnderDevelopment%2FFirmwareChanges

What is your particular case?

[mads b (dk)]

Its a Vw type1 engine with itb ~mild cam and we are chasing mpg

Regards Mads

[GintsK]

Naturally aspirated? For ITBs TPS signal represents engine load more accurately comparing to MAP.

But if you still want Speed-density at some point, you can build two separate tunes and do a switching between them at your desired window.  It has a built in hysteresis +/-100rpm IIRC.

In Vemstune go to Base setup->Config/table switch and hit F1 for description.

With this you can also build large VE map with 32 rpm bins.

[mads b (dk)]

It is a NA engine, so what your are saying is that its easyer and better just to use alpha-n with mapsensor baro

Regards Mads