Yes, I love my ECU. But my ECU is far from state of the art. For example it does NOT use AMM (air mass metering). Here is a clearer explanation.

Its a speed density system, that uses RPM's, absolute pressure, temperature to determine the air mass flow and maps fuel accordingly. The volumetric efficiency is accomodated within the O2 sensor adaption loop. The fuel mapping will trim to changes in humidity etc via the same method. This level of adaption accomodates variabilty in sensors and will also take changes to intake and exhaust in stride. So this is the ideal system for making mods.

The ECU system also analyzes the combustion process by using the spark plugs for measuring ionization within the cylinders. A weak voltage is applied across the gap of every spark plug after each combustion stroke. The current flowing back to the control unit is dependent on the number of ions that have been formed, which provides a measure of the combustion in each cylinder. Ionization measurement reveals whether the fuel/air mixture has ignited and burned correctly. If not, the system adjusts the fuel quantity, the Direct Ignition timing or the boost pressure. The Direct Ignition timing is also monitored separately in each cylinder. The Saab Trionic system can control each cylinder individually, which is a more accurate way of controlling the engine than by using averages of measurements carried out at only one point. This continuous monitoring enables the fuel energy to be put to optimum use. The result is a reduction in fuel consumption and exhaust emissions. Each fuel injector is controlled individually and the air mass entering the engine is calculated from measurements of pressure, temperature and air mass flow. The processor is so fast that it even checks during the injection phase whether any factors have changed, making in-cycle corrections if required by varying the fuel pulse from a minimum of two milliseconds (1/500th sec) to the complete four-stroke cycle. This makes the control of air/fuel ratio significantly more accurate and permits octane levels from 85 to 104 RON.

When the ECU sees a boost level that is above the max setting it has calculated as appropriate, it will engage fuel cutoff as a safety feature. Max boost is variable. Running 94 octane on cool days it will permit 21 PSI. Heat soak the intercooler by letting the car sit in the sun, get the temperature up to 120 degrees and run 87 octane, max boost will fall to about 8psi. No, you cannot disable the pressure sensor for the ECU as it will totally screw up the air/fuel mix. You want to make sure that boost is always below this max level, so MBCs need to be constantly adjusted to the level expected by the ECU.

What I want to fix is called boost lag.

The ECU controls the valve that actuates the wastegate on my turbo. This is a 3 way valve that has a feed from the throttle body, a line to the wastegate actuator and a vent to the intake. These 3 way valves are slow acting and contribute to boost lag (as opposed to turbo lag)... turbo spools quick but boost comes on slow. Presumably they did this with the stock valve to smooth throttle response and extend clutch life.

What I want to do is keep the ECU and swap out the bleeder valve with something that will act more quickly.