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HOWTO: Custom OS TMAP Switch over logic - Eg run 4+ bar of boost with a 2 bar map sensor.


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Problem: Running more than 2.5 bar of boost requires upgrading the boost and TMAP sensor which is expensive and can often cause drivability issues due to the decreased resolution of the new TMAP sensor.

Solution: Utilise our custom operating system and the "TMAP Configuration" feature which allows you to use a 4 bar boost sensor (or larger) with the standard 2.5 bar TMAP sensor. This adds logic to switch the speed density calculation over from using the TMAP sensor to the Boost sensor for it's calculation above a voltage set point. At high boost levels the air velocity is high enough there is no perceivable signal lag between the two sensors. This means you can retain the standard TMAP (cheaper and simpler) with it's factory resolution but still have full closed loop boost control at high boost levels with the standard fuelling model.

To enable this feature you require the workshop edition and a 5 credit "Standard Custom OS". This is an extra 2 credits on top of a standard license.

First open the custom operating system wizard, select "Standard Custom OS" and press Next.


You will then see a "Custom OS Options" page, leave these values as the standard values.


Press "Check License and Proceed" which will then ask you to license the file, this will charge you an extra 2 credits (totally 5 for the vehicle). This will only be charged once.

You will now see a second set of Custom OS options (these can be changed as many times as you like). Select "TMAP switch to Boost sensor after TMAP_Volts" from the "TMAP Configuration" drop down menu.


Press Next then "Finish" and the file will automatically save and re-open.

Now navigate to "Custom Operating System Configuration" within the navigator and locate "Voltage to switch from using the TMAP sensor to the boost sensor".


Now enter a value of 2.5v into auF100000. 2.1v is roughly 150kpa or 4psi of boost. If you leave the standard value of 15v this will effectively disable the switchover logic.


This means the sensor used in the speed density calculation will switch over at 4psi. You MUST have your boost sensor slope/offset set up correctly for the transition to be smooth. If you are unsure if this is case log both boost pressure and MAP pressure and ensure the values are equal at this boost pressure. If they are not either rescale your boost sensor or increase the voltage to where the two sensors become equal.

Ensure you have adjusted your TMAP max volts to above 5.0 V (TMAP sensor will peg at about 250 KPa but Bosch sensors are rated to work in an environment up to at least 5 bar). Change these settings (Speed Density -> Scalars):


We also changed the "Boost Sensor Volts Max Value"  to stop it causing a failure mode on overboost. You could set it to the voltage reading to a point slightly above the maximum boost you want to run to put in a safety margin in case of a hardware failure (like a wastegate jammed shut). 

If you purchase a 4 bar boost sensor from Independent Motorsport they can provide you with a PCMTEC parameter file with the slope and offset required.



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Just now, JETURBO said:

Nice one guys !

This has actually been available for a few years but we are finally writing up proper documentation for all of the guides so that all the features are documented and can be found in one place. There will be a master guide listing all the custom os features and their corresponding setup guide later today.

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