UENR0623-02 39 Engine Operation The programmable software contains all the fuel setting information. The information determines the engine performance. The ECM adjusts injection timing and fuel pressure for the best engine performance, the best fuel economy, and the best control of exhaust emissions. The actual timing can be viewed with an electronic service tool. Also, the desired timing can be viewed with an electronic service tool. Flash programming is the method of programming or updating the programmable software. Refer to Troubleshooting, “Flash Programming” for the instructions on the flash programming of the programmable software.
Fuel Injection The ECM is sealed and the ECM needs no routine adjustment or maintenance. The programmable software inside the ECM sets certain limits on the amount of fuel that can be injected. Engine Speed 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 to control the engines 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 electronic controls determine the injection timing, the amount of fuel that is delivered to the cylinders and the intake manifold pressure if an electronically controlled wastegate is installed. These decisions are based on the actual conditions and the desired conditions at any given time. The ECM has software that compares the desired engine speed to the actual engine speed. The actual engine speed is determined through the crankshaft speed/timing sensor and the camshaft speed/timing sensor. If the desired engine speed is greater than the actual engine speed, the ECM will instruct the electronic unit injector to inject more fuel to increase engine speed.
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. Timing Considerations The ECM controls the following characteristics: Once the ECM has determined the amount of fuel that is required, the software must determine the timing of the fuel injection. Fuel injection timing is determined by the ECM after considering input from the following components:
Boost pressure Operation of the NOx reduction system Diagnostic Codes Engine coolant temperature sensor When the ECM detects an electronic system problem, the ECM generates a diagnostic code. Also, the ECM logs the diagnostic code to indicate the time of the problems occurrence. The ECM also logs the number of occurrences of the problem. Diagnostic codes are provided to indicate that the ECM has detected an electrical problem or an electronic problem with the engine control system. Sometimes, the engine performance can be affected when the condition that is causing the code exists.
The sensor for the intake manifold air temperature The sensor for the intake manifold pressure Oxygen sensor 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. 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.