in a
Saab 900 Saab
Full Pressure Turbo (
FPT) models with this unit include the APC name displayed on a non-numeric boost
pressure gauge in the instrument panel. Although knock sensors are common even on non-turbocharged and turbocharged engines today, Saab has continued to use the APC name prominently as a differentiating feature. The white area on the left side of the scale shows
manifold vacuum under normal driving conditions, the short white dash is atmospheric pressure (engine off), the orange scale is where there is safe turbo
boost, the red scale is boost above 0.5 - 0.7
bar where the wastegate may be opened or a
fuel cut due to overboost may occur. Saab integrated the APC's boost control functionality with ignition control in 1990 with the introduction of the
DI/APC system, available in 9000 models only. The DI/APC system managed knock not only by decreasing boost via a solenoid but by retarding
ignition timing as well; DI/APC also managed the engine's basic ignition timing. == See also ==