Weber Injection-Ignition System; System Components; Operation Phases - MOTO GUZZI Daytona RS Workshop Manual

12

WEBER INJECTION-IGNITION SYSTEM

In the Weber injection-ignition system type "alfa/N" the engine speed and the throttle position are used to measure
the quantity of sucked air; when the quantity of air is known, measure the fuel quantity in relation with the desired
strength. Other sensors in the system allow to adjust the main operation, on particular condition. Moreover, the
engine speed and the throttle angle allow to calculate the optimal ignition advance on every operation condition.
The quantity of air sucked from each cylinder per cycle, depends on the air density in the suction manifold, on
the single displacement and on the volume efficiency. The volume efficiency is experimentally calculated on the
whole operation field of the motor (rpm and engine load) and is stored in the electronic unit. The control of the
injectors, each cylinder, is "time-sequenced", i.e. the two injectors are controlled on the basis of the suction
sequence, while the delivery can already begin, for each cylinder, from the expansion phase until the suction
phase, already begun. The timing for the initial delivery is contained in the electronic unit.
The ignition type is an inductive spark by static electronic devices, whose control pattern is memorised on an
EPROM in the central electronic control system.
12.1

SYSTEM COMPONENTS

Fuel circuit
Includes fuel tank, fuel pump, filter, pressure control system, and electronic injections.
The fuel is injected in the induction duct of each cylinder before the induction valve.
Intake Air Circuit
The circuit includes air filter induction duct and butterflied body .
The potentiometer which gives the butterflied position attached on the small shaft of the butterfly.
The absolute pressure transducer is on the filter box and is connected to it with a small tube. When the motorbike
speed increases, the pressure transducer detects the air pressure increase in the filter box which is due to the
increase of the air inflow from the air intake.
This pressure rise in the transducer into an electrical system, which modifies the injection timing of the mixture
in, order to optimise the carburation.
The air temperature transducer is in front and inside the fairing in order to avoids the direct influence of the engine
heat.
NOTE: For the model V10 CENTAURO the air temperature transducer is mounted on the right head
lamp holder.
Electric circuit
Includes the battery, the ignition distributor, to relays the electronic central system, the ignition group,
absolute pressure transducer air temperature transducer, butterflied position transducer (potential
meter). Two injectors, oil temperature transducer, phase and RPM transducer.
The electric circuit gives to the electronic control unit all the information about the engine conditions and transmits
the signals for the fuel injection and the variable advanced ignition control.
12.2

OPERATION PHASES

Normal operation
When the engine is in standard thermic conditions, the I.A.W. 16M unit calculates the phase, the injection time,
the ignition advance, only by interpolation on the corresponding stored presettings, according to rpm and throttle
position.
The resulting amount of fuel is delivered to the two cylinders with two subsequent injections.
The count of the initial delivery moment, for each cylinder, is made by means of a presetting that depends on the
number of revolutions.
Starting phase
When the ignition switch is in operation, the I.A.W. 16M unit feeds the fuel pump for few time and detects the
throttle angle and the temperature of the engine.
After starting the engine, the unit receives the revolution and phase signals, which allow it to control the injection
and the ignition.
To make the starting phase easy, an enrichment of the main quantity, upon the oil temperature, is performed.
After the starting phase, the unit begins the check of the advance.
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