MSD 7562 Programmable Launch Boost Controller Installation - Manual (Page 14)

14 INSTALLATION INSTRUCTIONS
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TEST EXAMPLE 4 - FIGURE 9
The next test data shows the effect of too much D term in the PID setup. Note on the rising edge of
the boost pressure, the large swing in the PWM value and the slower ramping of the boost pressure.
The boost pressure actually has a small step at 2.9-seconds at 10.4psi, well below the TargetPsi of
12psi. The boost pressure hesitates at 3-seconds before continuing to climb to the target pressure
value. It eventually reaches the target pressure and overshoots then drops back down and is seen
regulating with about 1psi of ripple pressure. The D term here is too big for the size of the
programmed P term. The P term is nearly optimum as it does not show signs of saturation. Reducing
the D term will allow quicker pressure rise and reach the target pressure regulation much quicker.
Here the D term should be reduced about –10- to –20 and then retested.
Figure 9