3 - | System components

Electronic Control Unit (ECU)
The engine ECU (1) is an electronic digital microprocessor-based unit.
It controls both the injectors and the coils, thus controlling fuel injection and ignition in accordance with the engine operating conditions detected by the following sensors:

- | Absolute pressure sensor (misures the barometric pressure and the engine load in Speed Density mode)

- | Air temperature sensor (measures intake air temperature)

- | Engine temperature sensor (measures the engine temperature)

- | Timing/rpm sensor for engine rotation speed and the position of each cylinder relative to TDC

- | Throttle position sensor (measures the throttle opening angle).

The ECU also monitors battery voltage so that it can adjust injector opening time and ignition coil charging time accordingly.
The ECU determines the following values.

- | Amount of fuel delivered to each cylinder with a sequential non-parallel control

- | Injector closing time and therefore injection timing relative to the end of the induction stroke for each cylinder

- | Ignition advance.

Important
The maps, which include ignition advance values, injection times, crankshaft angle for injector closing and all correction curves as a function of temperature and atmospheric pressure values, are stored in the Flash Eprom of the ECU. The above values are preset by the Manufacturer after testing the motorcycle under different riding conditions.
These settings cannot be changed.
Removal of the electronic control unit
In order to remove the ECU (1) it is first necessary to remove the fuel tank (Sect. L 2, Removal of the fuel tank), disconnect the ECU wiring connector (2) and unscrew the fixing screws (3).
Refitting the electronic control unit
Fix the ECU (1) to the airbox with the fours screws (3) and reconnect the wiring connector (2).
Tighten the screws (3) to the specified torque (Sect. C 3, Engine torque settings).
The connector (2) is 48 PIN connector.
Make sure that the clip (A) for the connector (2) is in its “open” position (as shown in the diagram).
Rotate the clip (A) to secure the connector (clip in the “locked” position).
Fuel injectors
The injectors (1) deliver the correct quantity of fuel required for optimal engine operation.
The ECU controls injector opening by feeding current to the coil of an electromagnet which creates a magnetic field to attract the armature, thereby generating fuel spray. If we take the physical characteristics of the fuel to be constant (viscosity, density), as well as the injector delivery and pressure head (controlled by the fuel pressure regulator), the amount of fuel injected depends on the duration for which the injector is open. This time is determined by the ECU in accordance with the engine operating conditions. In this way correct fuel delivery in ensured.
For removal or refitting of the injectors, refer to Sect. L 6, Removal of the fuel injectors.
Notes
To test the operation of the injector, use the DDS tester and follow the instructions given in the paragraph “Guided diagnosis”, (Sect. D 5).
The fuel output must be even and the jet should be fully atomised, without droplets.
Do not leave the engine stopped for a long time with the fuel circuit full. The fuel could clog the injectors and render them inoperable. Periodically, after lengthy periods without running the engine, we recommend adding TUNAP 231 to the fuel in the tank to help clean critical sections of the fuel circuit.
Positioning of the HT leads
Lambda sensor
The Lambda sensor, positioned on the exhaust pipe, transmits information to the ECU on the amount of oxygen present in the exhaust fumes. With this information the ECU can maintain optimal control over the fuel-air mixture.
The outer surface of the sensor element in zirconium dioxide is in direct contact with the exhaust gas, while the inner surface is in contact with the atmosphere. Both surfaces are coated with a thin layer of platinum. Oxygen in ionic form travels through the ceramic layer and charges the platinum layer electrostatically so that the platinum acts as an electrode: the electrical signal generated is carried on the sensor output cable.
the zirconium dioxide element becomes permeable to oxygen ions at a temperature of around 300 °C.
When the oxygen concentration is different on the two sensor surfaces, a voltage is generated thanks to the special physical properties of the zirconium dioxide. With a lean mixture the signal voltage is low, while with a rich mixture it is high.
The typical change in signal intensity occurs when the air-fuel ratio is 14.7 to 1 (14.7 parts of air to 1 part of petrol), which is referred to as “Lambda 1”. This ratio is considered to be an indication of complete combustion, hence the name “Lambda Sensor” (oxygen sensor) therefore
lambda = 1 means mixture in stoichiometric (ideal) ratio
lambda >1 means a lean mixture
lambda <1 means a rich mixture.
The air-fuel mixture control system is managed by the lambda sensor, which starts to operate at over 300 °C: the ceramic material starts conducting oxygen ions at around 300 °C. If the proportion of oxygen starts to differ between the two ends of the probe, this generates an electrical voltage between the two electrodes due to the particular nature of the material. This makes it possible to measure the difference in oxygen content between the exhaust gas and the ambient air. Combusted gas still contains a residual amount of oxygen when the air-fuel mixture delivered to the combustion chamber is incorrect. This makes it possible to adjust the injection control unit to ensure the engine always runs with the optimal air-fuel mixture.
To remove the lambda sensors (1) unscrew them from the horizontal and vertical cylinder exhaust pipes.
When refitting the sensors, tighten them to the specified torque (Sect. C 3, Frame torque settings).
Air pressure sensor
This sensor is powered by the ECU and it supplies information concerning the absolute air pressure in an area of the motorcycle that is not subject to turbulence. The electronic signals thus obtained are transmitted to the ECU, where they are used to make corrections in accordance with the pressure reading.
Notes
To test the operation of the injector, use the DDS tester and follow the instructions given in the paragraph “Guided diagnosis” (Sect. D 5).
Removing the air pressure sensor
To remove the air pressure sensor (1), remove the airbox (Sect. L 7, Removal of the airbox), disconnect the main wiring connector (3) from the sensor, and detach the sensor from the throttle body.
Remove the hoses (2) from the intake manifolds.
Refitting the air pressure sensor
Refitting is the reverse of removal.
On completion of the refitting operation, reconnect the wiring connector (3) to the sensor.
Refit the airbox (Sect. L 7, Refitting the oil breather valve).
Temperature sensor
This sensor is powered by the ECU and provides information regarding the temperature of the aspirated air.
The electronic signals thus obtained are transmitted to the ECU, where they are used to make corrections in accordance with the temperature reading.
Notes
To test the operation of the injector, use the DDS tester and follow the instructions given in the paragraph “Guided diagnosis” (Sect. D 5).
Removal of the air temperature sensor
To remove the air temperature sensor (1), first remove the airbox (Sect. L 7, Removal of the airbox), disconnect the main wiring harness connector from the sensor (1), unscrew and remove the two sensor retaining screws (2) and remove the sensor from the intake manifold of the vertical cylinder (3).
Refitting the air temperature sensor
Refitting is the reverse of removal.
On completion of the refitting operation, reconnect the wiring connector to the sensor (1).
Refit the airbox (Sect. L 7, Refitting the airbox).
Spark plug
Clean the area around the spark plug bores with a compressed air jet before removing the spark plugs themselves.
Remove the spark plug caps (1) from the spark plugs in both cylinder heads and remove the two spark plugs, making sure that no dirt or other objects enter the combustion chamber.
Important
Check the gap between the central and side electrodes.
If the gap is not as specified or if the spark plug is soiled with heavy sooty deposits, renew it.
Refit the spark plug in the cylinder head, first tightening it fully by hand.
Tighten to the specified torque (Sect. C 3, Frame torque settings).
Refit the spark plug caps (1).
Important
Do not use spark plugs with inadequate thermal rating or incorrect thread length. The spark plug must be securely installed. If a spark plug is loose, it can overheat and damage the engine.
Spark plug type
Make: NGK
Type: DCPR8E
Alternative
Make: CHAMPION
Type: RA6HC
Coil
An inductive discharge ignition system is used. Coil operation is governed by the M3C electronic control unit, which calculates the ignition advance. The power module (integrated in the electronic control unit) also guarantees constant energy coil charge, by adjusting the dwell time.
The horizontal cylinder coil (1) is located under the airbox; to remove it, it is first necessary to remove the LH air scoop cover (Sect. P 3, Starter contactor).
The vertical cylinder coil (2) is located on the battery support; to remove it, it is first necessary to remove the fuel tank (Sect. L 2, Removal of the fuel tank).
To remove the coil (1), disconnect the HT lead (3).
Unscrew the nuts (4), taking care to recover the spring washers (3).
Remove the coil (1) from the airbox.
To remove the coil (2), disconnect the HT lead (6) and remove the screws (7).
Remove the coil (2).
Refitting is the reverse of removal; tighten the nuts (4) and screws (7) to the specified torque (Sect. C 3, Frame torque settings).
Position the HT leads (3) and (6) as shown in the following photos.
Notes
To check the coils for faults, use the DDS tester and follow the instructions given in the paragraph “Guided diagnosis” (Sect. D 5).
Positioning of the HT leads
Throttle Position Sensor (TPS)
The TPS is powered by the ECU to which it sends a signal indicating the throttle position. This information is an indirect measure of the engine load and is used by the ECU as one of the main parameters for defining the fuel flow rate and spark advance.
Notes
To check this component, use the DDS tester following the instructions given in the paragraph “Guided diagnosis” (Sect. D 5).
It is not possible to change the throttle position sensor as a single component: in the event of a fault with the sensor the complete throttle body must be renewed (Sect. L 6, Removal of the throttle body).
Rpm/timing sensor
This sensor is of the inductive type: it faces the timing gear and is capable of “reading”the 44 teeth and the 2 gaps (each equivalent to 2 teeth) positioned 180° apart.
The signal coming from the pickup on the camshaft gear is used by the ECU to determine the engine speed and as a timing reference point.
Notes
To check these components for faults, use the DDS tester and follow the instructions given in the paragraph “Guided diagnosis” (Sect. D 5).
For instructions on how to renew the sensor and check the air gap, see the chapter “Flywheel - alternator” (Sect. N 8).
Main and injection relays
The relay (1) is positioned alongside the ECU and fixed to the airbox.
To remove the relay, raise the fuel tank (Sect. L 2, Removal of the fuel tank).
Disconnect the relay from the electrical system and apply 12 V (battery voltage) between contacts (86) and (85) (small contacts): you should hear a click that confirms that the internal electromagnet has switched.
Connect a multimeter to contacts (30) and (87) (big contacts) to check for electrical continuity (see Sect. P 9, Diagnostic instruments concerning operation of the multimeter). The resistance reading should be near zero and, if present, the continuity sound signal should be emitted. If this does not occur, the part must be renewed.