Electronic Fuel Injection System; Fuel Injection Control System - Suzuki DF 90 Service Manual

3-14 ENGINE CONTROL SYSTEM

ELECTRONIC FUEL INJECTION SYSTEM

The fuel injection system used by the DF90/DF115 is a speed-density, multi-point, sequential, electronic fuel
injection type.
The fuel injection system is composed of the fuel line components, air intake components, and components
for system control (ECM, sensors, switches, etc.).

FUEL INJECTION CONTROL SYSTEM

OUTLINE
Sensors are mounted at precise locations on the motor to monitor the current conditions of engine operation
and send signals to the ECM. Based on these signals, the ECM determines the optimum fuel injection time
duration (fuel amount), fuel injection timing (multi-point sequential timing) and controls the injector operating
signals accordingly.
Fuel injection start timing is set at BTDC445° on exhaust stroke constant.
Basic sensors
MAP sensor :
Informs ECM of intake manifold pressure.
CKP sensor :
Informs ECM of engine speed and crankshaft angle.
Compensating sensors
Cylinder temperature sensor :
Informs ECM of cylinder temperature.
IAT sensor :
Informs ECM of intake air temperature.
MAP sensor :
Informs ECM of barometric pressure at time of engine starting.
Battery voltage :
Constantly monitored by the ECM.
Others
CMP sensor :
Informs ECM of camshaft angle.
CTP switch :
Informs ECM of throttle position (open / closed).
Neutral switch :
Informs ECM of shift position (Neutral or in gear).
Battery
charge
coil
Rectifier &
regulator
30A fuse
60A fuse
Battery
ECM
main
relay
Ignition
switch
ECM
CPU
Injector
ECM
Fuel injection time duration
(amount) is determined by
a digital map designed in
relation to intake manifold
pressure and engine speed.
Fuel amount compensation
Multi-point sequential timing
Signal Signal Signal
Injector
Sensor / switch
signal input
(Voltage)
12V
A terminal voltage
Signal
Injection time
duration
(Time)