C4.4 Industrial Engine Electronic Control System Caterpillar

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 engine is equipped with an electronically controlled wastegate system for the turbocharger. 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.

The electronic control system has the following components:

• ECM

• Pressure sensor

• Temperature sensors

• Crankshaft speed/timing sensor

• Camshaft speed/timing sensor

• The suction control valve for the fuel injection pump

• Wastegate solenoid

• Electronic unit injectors

• Soot sensors

Engines with Series Turbochargers

Illustration 1	g02476176
(1) Air cleaner (2) Air inlet temperature sensor (3) Exhaust back pressure valve (4) Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF) (5) Inlet temperature sensor for the DPF (6) Soot sensor (7) Exhaust Cooler for the NOx Reduction System (NRS) (8) Turbochargers (9) Valve for the NOx Reduction System (NRS) (10) Temperature sensor for the NOx Reduction System (NRS) (11) Inlet pressure sensor for the NOx Reduction System (NRS) (12) Exhaust gas valve for the NOx Reduction System (NRS) (13) Air-to-air aftercooler (14) Wastegate regulator (15) Outlet pressure sensor for the NOx Reduction System (NRS) (16) Engine (17) Coolant temperature sensor (18) Crankshaft speed/timing sensor (19) Electronic unit injectors (20) Fuel cooler (21) Fuel pressure relief valve (22) Camshaft speed/timing sensor (23) Fuel injection pump and fuel temperature sensor (24) Fuel pressure sensor (25) Oil pressure sensor (26) Atmospheric pressure sensor (27) ECM (28) Fuel transfer pump (29) Primary fuel filter (30) Fuel strainer (31) Boost pressure sensor (32) Inlet manifold temperature sensor (33) Transfer pump inlet regulator (34) Secondary fuel filter (35) Fuel tank

Engines with a Single Turbocharger

Illustration 2	g02420296
Typical example (1) Air cleaner (2) Air inlet temperature sensor (3) Exhaust Cooler for the NOx Reduction System (NRS) (4) Exhaust back pressure valve (5) Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF) (6) DPF inlet temperature sensor (7) Soot sensor (8) Turbocharger (9) Valve for the NOx Reduction System (NRS) (10) Temperature sensor for the NOx Reduction System (NRS) (11) Inlet pressure sensor for the NOx Reduction System (NRS) (12) Exhaust gas valve for the NOx Reduction System (NRS) (13) Air-to-air aftercooler (14) Wastegate regulator (15) Outlet pressure sensor for the NOx Reduction System (NRS) (16) Engine (17) Coolant temperature sensor (18) Crankshaft speed/timing sensor (19) Electronic unit injectors (20) Fuel cooler (21) Fuel pressure relief valve (22) Camshaft speed/timing sensor (23) Fuel injection pump and fuel temperature sensor (24) Fuel pressure sensor (25) Oil pressure sensor (26) Atmospheric pressure sensor (27) ECM (28) Fuel transfer pump (29) Primary fuel filter (30) Fuel strainer (31) Inlet manifold pressure sensor (32) Inlet manifold air temperature sensor (33) Transfer pump inlet regulator (34) Secondary fuel filter (35) Fuel tank

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 3	g02476638
(1) Coolant temperature sensor (2) Fuel pressure sensor (3) Inlet manifold temperature sensor (4) Boost pressure sensor (5) Electronic Control Module (ECM) (6) Atmospheric pressure sensor (7) Crankshaft speed/timing sensor (8) Engine oil pressure sensor (9) Fuel temperature sensor (10) Suction control valve for the fuel injection pump (11) Wastegate regulator (12) Inlet pressure sensor for the NOx Reduction System (NRS) (13) Outlet pressure sensor for the NOx Reduction System (NRS) (14) Exhaust gas valve for the NOx Reduction System (NRS) (15) Temperature sensor for the NOx Reduction System (NRS)

Illustration 4	g02476647
(16) Exhaust back pressure valve (17) Camshaft speed/timing sensor (18) Water in fuel switch (19) Oil level switch (if equipped) (20) Electric fuel transfer pump

Illustration 5	g02476653
(1) Coolant temperature sensor (2) Fuel pressure sensor (3) Inlet manifold temperature sensor (4) Boost pressure sensor (5) Electronic Control Module (ECM)

Illustration 6	g02476657
(6) Atmospheric pressure sensor (7) Crankshaft speed/timing sensor (8) Engine oil pressure sensor

Illustration 7	g02476662
(9) Fuel temperature sensor (10) Suction control valve for the fuel injection pump (11) Wastegate regulator (12) Inlet pressure sensor for the NOx Reduction System (NRS) (13) Outlet pressure sensor for the NOx Reduction System (NRS)

Illustration 8	g02476672
(14) Exhaust gas valve for the NOx Reduction System (NRS) (15) Temperature sensor for the NOx Reduction System (NRS) (16) Exhaust back pressure valve

Illustration 9	g02476674
(17) Camshaft speed/timing sensor

Illustration 10	g02476676
(18) Water in fuel switch (19) Oil level switch (if equipped) (20) Electric fuel transfer pump

Sensor Locations for the Clean Emissions Module

Illustration 11	g02395776
Typical example (1) Temperature sensor (2) Connector for temperature sensor (3) Soot sensor connection (4) Aftertreatment identification module (5) Soot sensor connection (6) Soot sensor module

Note: The location of the soot sensor module will depend on the application.

ECM

Illustration 12	g01926054
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 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 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.

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 AVSpare dealers. 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".

Speed/Timing Sensors

Illustration 13	g02155463
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 14	g02476196
Typical example

The secondary speed/timing sensor is located on the right-hand side of the cylinder block toward the rear of the engine. The secondary speed/timing sensor generates a signal that is related to the camshaft position. The secondary speed/timing sensor detects the movement of the teeth on the timing ring (2) for the camshaft. 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 15	g01878676
Schematic for speed/timing sensor

When the engine is cranking, the ECM uses the signal from the speed/timing sensor on the camshaft. 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 16	g02139716
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 17	g02139713
Schematic for the engine temperature sensors

Illustration 18	g02139706
Schematic for the temperature sensors for the engine aftertreatment system

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 operating range for the fuel temperature sensor ... -40° to 120°C (-40° to 248°F)

The sensors are also used for engine monitoring.

Sensors for the NOx Reduction System (NRS)

Illustration 19	g02139786
A typical example of a schematic of the position sensors for the NOx Reduction System (NRS)