C4.4 Engines for Caterpillar Built Machines Electronic Control System Caterpillar


Electronic Control System
`
C4.4 Engines for Caterpillar Built Machines [UENR4524]
ELECTRICAL AND STARTING SYSTEM
CONTROL GP-ELECTRONIC
C4.4 Engines for Caterpillar Built Machines Electronic Control System
1.1. Introduction
2.1. Sensor Locations for the Engine
3.1. ECM
4.2. Engine Speed
5.2. Timing Considerations
6.2. Fuel Injection
7.1. Diagnostic Codes
8.2. Event Codes
9.1. Passwords
10.1. Speed/Timing Sensors
11.1. Pressure Sensors
12.1. Temperature Sensors

Introduction

The engine is designed for electronic control. The engine has an Electronic Control Module (ECM), a fuel injection pump and electronic unit injectors. All of these items are electronically controlled. There are also a number of engine sensors. The ECM controls the engine operating parameters through the software within the ECM and the inputs from the various sensors. The software contains parameters that control the engine operation. The parameters include all of the operating maps and customer-selected parameters.



Illustration 1g03518599
Typical example
(1) Air cleaner
(2) Air inlet temperature sensor
(3) Turbocharger
(4) Engine
(5) Coolant temperature sensor
(6) Air-to-air aftercooler
(7) Crankshaft speed/timing sensor
(8) Electronic unit injectors
(9) Solenoid for the fuel injection pump
(10) Secondary speed/timing sensor
(11) Fuel injection pump
(12) Fuel transfer pump
(13) Priming pump
(14) Primary fuel filter
(15) Fuel pressure sensor
(16) Oil pressure sensor
(17) ECM
(18) Inlet manifold pressure sensor
(19) Inlet manifold air temperature sensor
(20) Secondary fuel filter
(21) Fuel tank

The electronic control system has the following components:

  • ECM

  • Pressure sensor

  • Temperature sensors

  • Crankshaft speed/timing sensor

  • Camshaft speed/timing sensor

  • The solenoid for the fuel injection pump

  • Electronic unit injectors

Sensor Locations for the Engine

The illustrations in this section show the typical locations of the sensors for the industrial engine. Specific engines may appear different from the illustration due to differences in applications.



Illustration 2g03519477
Typical example of sensor locations on the left side of the engine
(1) Coolant temperature sensor
(2) Inlet manifold pressure sensor
(3) Solenoid for the fuel injection pump
(4) Inlet manifold temperature sensor
(5) Fuel pressure sensor
(6) Electronic Control Module (ECM)
(7) Primary speed/timing sensor
(8) Oil pressure sensor
(9) Secondary speed/timing sensor


Illustration 3g03519480
Typical example of close up views of sensor locations on the left side of the engine
(1) Coolant temperature sensor
(2) Inlet manifold pressure sensor
(3) Solenoid for the fuel injection pump
(4) Inlet manifold temperature sensor
(5) Fuel pressure sensor
(6) Electronic Control Module (ECM)
(7) Primary speed/timing sensor
(8) Oil pressure sensor
(9) Secondary speed/timing sensor

ECM



Illustration 4g03347127
Typical example

The Electronic Control Module (ECM) (1) functions as a governor and a computer for the fuel system. The ECM receives signals from the sensors in order to control the timing and the engine speed.

The electronic system consists of the ECM, the engine sensors, and inputs from the parent machine. The ECM is the computer. The personality module is the software for the computer. The personality module contains the operating maps. The operating maps define the following characteristics of the engine:

  • Engine rating

  • Torque curves

  • High and low idle speed (rpm)

  • Emissions

  • Injection timing

The factory passwords restrict changes to authorized personnel. Factory passwords are required to clear any event code. Refer to Troubleshooting, "Factory Passwords" for more information on the passwords.

The ECM has an excellent record of reliability. Any problems in the system are most likely to be the connectors and the wiring harness. The ECM should be the last item in troubleshooting the engine.

The programmable software contains all the fuel setting information. The information determines the engine performance.

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.

The ECM is sealed and the ECM needs no routine adjustment or maintenance.

Engine Speed

The electronic controls determine the injection timing, the amount of fuel that is delivered to the cylinders and the intake manifold pressure. 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 secondary 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 in order to increase engine speed.

Timing Considerations

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:

  • Engine coolant temperature sensor

  • The sensor for the intake manifold air temperature

  • The sensor for the intake manifold pressure

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. The actual timing can be viewed with an electronic service tool. Also, the desired timing can be viewed with an electronic service tool.

Fuel Injection

The programmable software inside the ECM sets certain limits on the amount of fuel that can be injected.

The Fuel Ratio Control (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

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 problem's 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 AVSpare dealers. Since factory passwords contain alpha-numeric 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".

Speed/Timing Sensors



Illustration 5g03538902
Typical example

The primary speed/timing sensor is located on the left-hand side of the cylinder block close to the flywheel housing. The primary speed/timing sensor generates a signal by detecting the movement of the teeth that are located on the crankshaft timing ring (1). The signal that is generated by the speed/timing sensor is transmitted to the ECM. The ECM uses the signal from the speed/timing sensor to calculate the position of the crankshaft. The signal is also used to determine the engine speed.



Illustration 6g03538918
Typical example

The secondary speed/timing sensor is located on the left-hand side of the cylinder block under the fuel injection pump. The secondary speed/timing sensor detects the movement of the fuel injection pump drive gear (2). The signal that is generated by the speed/timing sensor is transmitted to the ECM. The ECM calculates the speed and the rotational position of the engine by using the signal. The secondary speed/timing sensor is required for starting purposes.



Illustration 7g03347142
Schematic for the speed/timing sensor

When the engine is cranking, the ECM uses the signal from the secondary speed/timing sensor. When the engine is running the ECM uses the signal from the speed/timing sensor on the crankshaft. This speed/timing sensor is the primary source of the engine position.

Pressure Sensors



Illustration 8g03538938
Schematic for the pressure sensors

The boost pressure sensor and the engine oil pressure sensor are active sensors.

The boost pressure sensor provides the ECM with a measurement of inlet manifold pressure in order to control the air/fuel ratio. This will reduce the engine smoke during transient conditions.

The operating range of the boost pressure sensors is 39 to 400 kPa (6 to 58 psi).

The engine oil pressure sensor provides the ECM with a measurement of engine oil pressure. The ECM can warn the operator of possible conditions that can damage the engine. This includes the detection of an oil filter that is blocked.

The operating range for the engine oil pressure sensor ... 13 to 1200 kPa (2 to 174 psi)

Temperature Sensors



Illustration 9g03538937
Schematic for the engine temperature sensors

The air inlet temperature sensor and the coolant temperature sensor are passive sensors. Each sensor provides a temperature input to the ECM. The ECM controls following operations:

  • Fuel delivery

  • Injection timing

The operating range for the sensors ... −40° to 125°C (−40° to 257°F)

The sensors are also used for engine monitoring.