Fuel Injection Control; Fuel Injection Timing - TOHATSU MFS 25D Service Manual

Fuel System (Fuel Injection)

(3) Fuel Injection Control

The ECU calculates the intake air quantity based on the engine revolution speed and intake manifold pressure
(intake vacuum pressure) to determine the fuel injection amount.
During engine startup, warm-up, acceleration/deceleration, and idling, the ECU performs correction control based on
information from the sensors.
Pulser Coil
T-MAP (Manifold Pressure,
Manifold Temperature) Sensor
TPS (Throttle Position) Sensor
Engine Temperature Sensor

1) Fuel Injection Timing

Fuel injection timing at starting and during normal operation are described in the following table.
Cylinder No.
1
2
3
Remarks: 1) No. of fuel injections
2) Injection sequence
3) Combustion sequence : #1
4) Injection timing diagram is shown below.
Crank Angle Signal
of No. 1 Cylinder
Crank Angle Signal
of No. 2 Cylinder
Crank Angle Signal
of No. 3 Cylinder
Injector of No. 1
Cylinder
Injector of No. 2
Cylinder
Injector of No. 3
Cylinder
Strokes of No. 1 Cylinder
Strokes of No. 2 Cylinder
Strokes of No. 3 Cylinder
4-22
Engine Revolution Speed and Crank Angle
Manifold Pressure (Intake Vacuum Pressure)
Manifold Intake Air Temperature
Atmospheric Pressure at Starting
Change of Pressure (Vacuum Pressure)
at Acceleration/Deceleration
Cylinder Cooling Water Temperature
Reference Signal
#1 Crank Angle Signal
#2 Crank Angle Signal
#3 Crank Angle Signal
: Once per revolution of each cylinder (around the end of the compression and
exhaust strokes)
: #1 #2 #3
#3 #2
Exhaust Intake
Compression Combustion
Combustion Exhaust
Injection Timing Diagram
Correction
Injection Timing (with reference to individual cylinders)
BTDC 365° and BTDC 5°
BTDC 365° and BTDC 5°
BTDC 365° and BTDC 5°
#1 #2 #3 #1 (for every 120° of the crank angle)
#1 (for every 240° of the crank angle)
compression stroke top dead center)
Compression Combustion
Exhaust
Intake Compression
Basic
Injection
Injection
Amount
Amount
ECU
(with reference to No. 1 cylinder
Injection
Timing
Exhaust
Intake Compressi o n
Combustion
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