© 2002 Cannondale Corporation - All Rights Reserved
6
Electrical_EFI Service Manual.fm
ENGINE MANAGEMENT SYSTEM
(EMS)
Engine operation is supported by the management
system consisting of three main types of electrical
components: the ECU, the sensors, and the actu-
ators.
•
The engine control unit (ECU or ECM) precisely
calculates ignition timing and fuel delivery for all
engine speeds and loads (based on the
currently installed calibration file and its
mapping). The ECU is an extremely reliable
component and should be the last component
checked in the event there is a problem with the
fuel injection system.
•
The sensors of the system collect engine
operating information and transmit it to the
ECU.
•
The actuators are devices like the fuel injectors,
fuel pump, fuel pressure regulator, and spark
plug coil, and relays.
ENGINE CONTROL UNIT (ECU)
The engine control unit or “ECU” is a kind of com-
puter that calculates ignition timing and fuel delivery
for all engine speeds and loads based on its pro-
gramming. It is sometimes referred to as the “brain”
of the fuel injection system. This brain calculates fuel
delivery and ignition timing based on information
gathered from vehicle sensors (inputs) and the cali-
bration file loaded at the factory.
The ECU inputs are the air temperature, coolant,
crankshaft position, throttle position, and barometric
pressure sensors. Information from these sensors
together with the ECU operating code (hex file) and
engine calibration file (map) are used to control the
system actuators (e.g. fuel pump, ignition coil,
injectors, relays, idle air control valve).
NOTE :
In this manual, the engine control unit is referred
to as the “ECU.” It is also sometimes called an
“ECM” or engine control module. Either reference
is OK.
Motorcycle ECUs are located within the subframe.
ATV ECUs are located on the electronics tray under
the cowl.
1. ECU
2. Air pressure sensor hose (from airbox and fuel pressure
regulator)
3. Internal barometric (air) pressure sensor.
1. ECU
2. Air pressure sensor hose (from airbox)
3. Accessories connector
4. EMS power relay
1
2
3
2
3
3
4
1
