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Repair manual KTM LC8 Art.-No. 3.206.035-E
INJECTION/IGNITION SYSTEM
Establishing the injection period (injection volume)
Generally, the injection volume, i.e. the quantity of injected fuel, is dependent on the fuel pressure and the time the injection
valve is open. Since the fuel pressure regulator keeps the fuel pressure constant, the quantity of fuel injected is controlled by the
time the injection valve is open.
The basic injection rate is determined by the engine speed and manifold air pressure or throttle valve position; the opening
period is directly dependent on the engine load (manifold air pressure/throttle valve signal); fuel is injected every 720° crank
angle (every other rotation).
Additional sensors establish the operating conditions and driving conditions (e.g.: coolant and air temperature, ambient air
pressure, battery voltage, etc.); the basic injection rate is corrected based on the signals received from these sensors.
Manifold air pressure sensors/
throttle valve sensor
Pulse generator
Corrective sensors/inputs
Control unit (ECU)
Injection valves
Basic injection rate
Correction
Actual injection rate
SENSOR/INPUTS INFORMATION
Coolant temperature sensor
Throttle valve sensor
Air temperature sensor
Ambient air pressure sensor
Lambda probes
Battery voltage
CORRECTION SENSORS AND INPUTS
The injection time must be prolonged and the idle speed increased for a
cold start and during the warming-up phase (required for starting
enrichment and a steady warming-up).
The quantity injected is dependent on the TPS position in the upper
load/speed range, it also influences the ignition.
The injection time is prolonged at a lower intake air temperature and
reduced at a high temperature.
The injection time is reduced at a low ambient air pressure (e.g.: uphill
driving) and prolonged at a high ambient air pressure (the oxygen level
of the intake air drops as the altitude increases).
The oxygen level in the emission (rich-mixture combustion results in
less residual oxygen, lean combustion in more residual oxygen).
The injection time is prolonged at a low battery voltage.
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