At start-up, the ECM determines the TOP CENTER
position of the number 1 cylinder from the secondary
speed/timing sensor on the camshaft. The ECM
decides when fuel injection should occur relative to
the TOP CENTER position. The ECM optimizes
engine performance by control of each of the
electronic unit injectors so that the required amount
of fuel is injected at the precise point of the engine's
cycle. The electronic unit injectors are supplied high-
pressure fuel from the fuel manifold. The ECM also
provides the signal to the solenoid in the fuel injection
pump. The solenoid in the fuel injection pump
controls a valve in the fuel injection pump. This valve
controls the volume of fuel that enters the plungers.
By controlling the volume of fuel that enters the
plungers, this controls the pressure in the fuel
manifold. Fuel that is not required for the engine is
diverted away from the fuel injection pump back to
the fuel tank.
The ECM adjusts injection timing and fuel pressure
for the best engine performance, the best fuel
economy, and the best control of exhaust emissions.
Fuel Injection
The programmable software inside the ECM sets
certain limits on the amount of fuel that can be
injected.
The FRC Limit is a limit that is based on intake
manifold air pressure and engine rpm. The FRC Limit
is used to control the air/fuel ratio in order to control
the engine's exhaust emissions. When the ECM
senses a higher intake manifold air pressure, the
ECM increases the FRC Limit. A higher intake
manifold air pressure indicates that there is more air
in the cylinder. When the ECM increases the FRC
Limit, the ECM allows more fuel into the cylinder.
The Rated Fuel Limit is a limit that is based on the
power rating of the engine and on the engine rpm.
The Rated Fuel Limit enables the engine power and
torque outputs to conform to the power and torque
curves of a specific engine model.
These limits are in the programmable software and
these limits cannot be changed.
The ECM controls the following characteristics:
• Boost pressure
• Operation of the NOx reduction system
Diagnostic Codes
When the ECM detects an electronic system
problem, the ECM generates a diagnostic code. Also,
the ECM logs the diagnostic code in order to indicate
the time of the problems occurrence. The ECM also
logs the number of occurrences of the problem.
Diagnostic codes are provided in order to indicate
that the ECM has detected an electrical problem or
an electronic problem with the engine control system.
In some cases, the engine performance can be
affected when the condition that is causing the code
exists.
If the operator indicates that a performance problem
occurs, the diagnostic code may indicate the cause
of the problem. Use a laptop computer to access the
diagnostic codes. The problem should then be
corrected.
Event Codes
Event Codes are used to indicate that the ECM has
detected an abnormal engine operating condition.
The ECM will log the occurrence of the event code.
This does not indicate an electrical malfunction or an
electronic malfunction. If the temperature of the
coolant in the engine is higher than the permitted
limit, then the ECM will detect the condition. The
ECM will then log an event code for the condition.
Passwords
System Configuration Parameters are protected by
factory passwords. This will prevent unauthorized
reprogramming of the system and the unauthorized
removal of logged events. Factory passwords are
calculated on a computer system that is available
only to Perkins distributors. Since factory passwords
contain alphabetic characters, only an electronic
service tool may change System Configuration
Parameters. System Configuration Parameters affect
the power rating or the emissions. Passwords also
allow the customer to control certain programmable
engine parameters.
Refer to Troubleshooting, “Programming
Parameters” and Troubleshooting, “Factory
Passwords”.
UENR4490-01 63
Engine Operation
This document has been printed from SPI2. NOT FOR RESALE
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