MPI <4G9> -
Troubleshooting
13A-89
FAIL-SAFE FUNCTION REFERENCE TABLE
When the main sensor malfunctions are detected by the diagnosis function, the vehicle is controlled
by means of the pre-set control logic to maintain safe conditions for driving.
Malfunctioning item
Control contents during malfunction
Air flow sensor
1. Uses the throttle position sensor signal and engine speed signal (crank angle sensor
signal) to take reading of the basic injector drive time and basic ignition timing from
the pre-set mapping.
2. Fixes the ISC servo in the appointed position so idle control is not performed.
Intake air temperature
sensor
Controls as if the intake air temperature is 25
_
C.
Throttle position
sensor (TPS)
No increase in fuel injection amount during acceleration due to the throttle position sensor
signal.
Engine coolant
temperature sensor
Controls as if the engine coolant temperature is 80
_
C.
Camshaft position
sensor
Injects fuel to all cylinders simultaneously.
(However, after the ignition switch is turned to ON, the No. 1 cylinder top dead centre is not
detected at all.)
Barometric pressure
sensor
Controls as if the barometric pressure is 101 kPa.
Detonation sensor
Switches the ignition timing from ignition timing for super petrol to ignition timing for standard
petrol.
Ignition coil, power
transistor
Cuts off the fuel supply to cylinders with an abnormal ignition.
Oxygen sensor (front)
Air/fuel ratio feedback control (closed loop control) is not performed.
Oxygen sensor (rear)
Performs the feedback control (closed loop control) of the air/fuel ratio by using only the
signal of the oxygen sensor (front) installed on the front of the catalytic converter.
Alternator FR terminal
Does not control the output of the alternator according to an electrical load. (works as a
normal alternator)
Misfiring
If the detected misfiring causes damage to the catalyst, the misfiring cylinder will be shut
down.
