Engine System Overview 2.3.6 Intake Air Heater (C7 ACERT and C9 ACERT, HEUI Only) The engines are equipped with an electric heater that is located behind the air inlet elbow. The electric heater has two functions: • Aid in starting • Aid in white smoke cleanup during start-up The intake air heater works in conjunction with the wait-to-start lamp. NOTE: If an ether starting aid is used on C7 ACERT or C9 ACERT engines, it must be controlled by the engine ECU so that ether is not injeced while the intake air heater is in use. Refer to section 16.4.
2.3.7 Fuel Pressure Sensor (C7 ACERT-C18 ACERT Only) Prior to exiting the fuel filter base, the fuel pressure is sampled by the fuel pressure sensor. The signals that are generated by the sensor are used by the engine control in order to monitor the condition of the engine’s injectors. This information is used to adjust the fuel delivery of the engine in order to optimize efficiency and to protect the injectors. 2.3.8 Dual Speed Timing Sensors The engine speed/timing sensors are used to determine both engine speed and fuel injection timing. The C7 ACERT and C9 ACERT sensors are both triggered by a target wheel on the camshaft.
On the C11 ACERT through C32 ACERT, the camshaft position sensor detects information from a target wheel on the camshaft and the crankshaft position sensor detects this information from a target wheel on the crankshaft. Under normal operating conditions the engine monitors one of the position sensors while cranking (camshaft) and one of the position sensors (crankshaft) while running. The design provides for optimized start capability as well as redundancy. Should a failure occur in either of the sensor circuits, the engine can be started and will run with only one sensor.
2.3.9 Compression Brake Solenoids (Option on C15 ACERT and C18 ACERT Only) Compression brake is an optional feature offered on select C15 and C18 ratings only. There is one compression brake actuator assembly per pair of adjacent cylinders and one control solenoid per brake assembly. The ECU directly drives the solenoid through the engine harness. Contact the Caterpillar Application Support Center for ratings that are approved to use a compression brake. Refer to Exhaust and Compression Brakes (section 10) for more information. 2.3.10 Fuel Temperature Sensor (C11 ACERT-C32 ACERT) Fuel temperature is measured at the fuel filter base. Fuel is sampled prior to fuel exiting the fuel filter base.
Fuel temperature is monitored to adjust fuel rate calculations as part of a fuel temperature power compensation strategy to maintain constant power when fuel temperature exceeds 30° C. Refer to the Fuel Temperature (C11 ACERT-C18 ACERT only) (section 15.1.6) in the Engine Monitoring and Protection section for more information on fuel temperature compensation. 2.3.11 Atmospheric Pressure Sensor The atmospheric pressure sensor is an absolute pressure sensor measuring crankcase pressure. Both the boost pressure and oil pressure communicated to service tools and over the data link are calculated by subtracting the atmospheric pressure sensor reading.
The atmospheric pressure sensor can measure pressures from 0 kPa (0 psi) to 116 kPa (16.8 psi). The engine implements altitude compensation (derate) strategies based partially on input from this sensor. I N D U S T R I A L E N G I N E E L E C T R O N I C S 10