[Auberon]

Please understand what you are dealing with before you fiddle if that is possible. Following is an exceptionally brief outline of what you are toying with:

The Standard Embedded Bosch Control strategy for the EGR and TVA systems uses proportional plus Integral (PI) control structure with feed-forward terms. The MAF is measured upstream of the compressor and is used to close the loops on the EGR and TVA systems. The 2 outputs are switched by the controller by suitable logic and divided into the EGR and TVA systems. The gains of the 2 PI controllers depend on suitable maps resulting from the engine fuelling and speed.

The setpoints of these two coordinated controllers are derived from extrinsic mapping driving actuators to maintain combustion conditions as closely as possible to the stoichiometric ratio.

In the open-loop mode it cannot guarantee accurate tracking due to engine variability, aging and driving environment. The BOSCH strategy employs emperically determined parameters (by VM's own calibration engineers) but there are LIMITS to this automatic strategy as this tends to assume linearity.

There is also a relationship to which I have pointed before that relies on the sensor creating a feedback loop to the standard ECU through a series of COMPLEX steps based on first principles.

Predictive controllers have the advantage that actuator positioning is no longer needed. This is probably what MAY allow you to block off ports....at a pinch on certain models but your gains would be questionable. Generally, setpoints should be simultaneously reached and should cover the relevant operating parameters (pre-determined from known data sets).

None of this can be done without consideration of engine operating conditions including cetane number, fuel freshness, air density, RH, TP, load, oil type etc.

So my advice is to tread carefully.
Cheers
Auberon