Air Intake System
The air intake system is shown in the diagram below.
The incoming air charge passes through the air cleaner to the air flow meter.
where the air flow rate and temperature are measured. The air then goes to the
surge tank where it is distributed to the four intake ducts. A throttle valve in
each intake duct controls the air flow to each cylinder.
The surge tank ha~ twO functions. The first is to .reduc~ t~e inf1uen~e of a!r flo~
pulsation on the aIr flow meter. and the second IS to distTlbute the Incommg aIr
to each cylinder.
There is a separate throttle valve for each cylinder. and they must be synchronized just as on a normally carburetted engine.
1. THROTTLE VALVE
2. SURGE TANK
3. AIR FLOW METER
4. AIR CLEANER
Electronic Control Unit
The electronic control system is shown below.
The following signals are electrically sent to the control unit from the various
sensors:
I. Engine speed: Picked up at the ground sides of the primary windings of the
ignition coils.
2. Air flow rate: Measured by the air flow meter.
5. Stan signal: Picked up at the positive side of the staner relay.
4. Throttle valve: On the throttle valve shaft is a switch which signals the idle
position and the full· load position of the throttle valves.
5. Engine temperature: Picked up by the engine temperature sensor on the
cylinder head.
6. Air temperature: Picked up by the air temperature sensor built into the air
flow meter.
The control unit receives these signals as input data and processes them in ac·
cordance with a predetermined program. The control unit then computes the
duration of fuel injection required to meet the needs of the engine. and sends a
signal pulse to the injectors. Each fuel injector opens its valve according to the
pulses received. and the correct amount of fuel is injected into each intake
manifold.
.
The major advantage of this "air flow sensitive" 'System is that the air flow is
measured before it reaches the cylinders. This allows the control unit to compute
the proper amount of fuel before it is needed.
1. BATTERY
2. IGNmON SWITCH,
3. STARTER BUTTON
4. RELAY
5. CONTROL UNIT
e.FUELPUMP
7. THROTTLE VALVE SWITCH
e. FUEL INJECTOR
9. ENGINE TEMPERATURE SENSOR
10. AIR FLOW METER
11. AIR TEMPERATURE SENSOR
12. IGNITION COILS
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