Loyale Sedan (4 Door) 4WD F4-1781cc 1.8L SOHC Turbo (1990)
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Overboost Switch: Description and Operation
Pressure Switch
PURPOSE
Signals the ECU when an over-boost condition occurs. Illuminates the boost indicator lamp in the instrument cluster.
LOCATION
On front of R.H. strut tower.
OPERATION
The switch incorporates two sets of contacts:
^ One set of contacts closes when manifold pressure reaches +1.97 inHg (6.7 Kpa) causing the turbo lamp in the instrument cluster to turn on. It
also signals the ECU that the engine is operating under a heavy load condition. The ECU then cancels closed-loop feedback, placing the A/F
mixture at "Full-Rich."
^ The second set of contacts closes when manifold pressure reaches +18.5 in.Hg (62.7 kPa). This signals the ECU that a malfunction has occured
in the turbocharger (excessive boost). The ECU turns off the fuel injectors, preventing engine damage.
