BEARING 4H7701 - Caterpillar

System Operation Description:The clean gas induction (CGI) system routes clean gas from the outlet of the Diesel Particulate Filter (DPF) to the inlet of the turbocharger. The CGI system consists of the following components:
CGI cooler
Sensor group
Control groupCGI CoolerThe CGI cooler uses engine coolant to cool the clean gas.Sensor GroupThe sensor group consists of these components:Venturi - The venturi is a restriction in the duct between the DPF and the turbocharger. Two pressure taps on the venturi provide connection points for tubing.Tubing - Tubing connects the venturi's pressure taps to two pressure sensors.Sensors - Three sensors sense the parameters of the clean gas.The sensor group produces electrical signals that indicate the values of the following parameters:CGI Temperature - This is the temperature of the clean gas in the duct.CGI Absolute Pressure - This is the absolute pressure of the clean gas in the duct.CGI Differential Pressure - This is the pressure drop across the venturi.Electrical wiring sends the signals from the sensors to the Engine Control Module (ECM). The ECM uses the signals to determine the mass of the clean gas that is flowing into the turbocharger.The ECM creates a pulse width modulated signal (PWM) that indicates the amount of clean gas that is desired. Wiring sends the PWM signal from the ECM to the control group.Control GroupThe control group consists of the following components:Coil - The coil receives the PWM signal from the ECM. The coil creates a magnetic field that is detected by the actuator.Actuator - The actuator uses pressurized engine oil to convert the coil's magnetic field to rotation of a shaft. The shaft is connected to the valve assembly.Valve Assembly - The valve assembly contains a flapper. The flapper is connected to the actuator's shaft. The flapper moves in order to vary the amount of clean gas that flows into the turbocharger.During normal engine operation, the ECM commands the flapper to a position that results in the desired flow of clean gas. Illustration 1 shows the flapper in the closed position and in the open position. The ECM can command the flapper to any position between the closed position and the open position.
Illustration 1 g01384096
Sectional view of a typical CGI valve assembly
Illustration 2 g01319012
Component identification on the C7 and C9 enginesThis is a typical view. The location of control group (4) and (6) and temperature sensor (5) depends on the chassis. (1) Differential pressure sensor (2) Absolute pressure sensor (3) Tubing (4) Valve assembly (5) Temperature sensor (6) Actuator (7) Venturi (8) CGI cooler
Illustration 3 g01319058
Component identification on the C13 and C15 engine (3) Tubing (5) Temperature sensor (7) Venturi (8) CGI cooler
Table 1
Codes for the CGI System    
J1939 Code    Description    Comments    
520192-15     CGI Mass Flow Rate : High - Least Severe (1)     The flow of clean gas is consistently excessive. A snapshot is triggered. The code is logged.    
520192-16     CGI Mass Flow Rate : High - Moderate Severity (2)     The flow of clean gas is consistently excessive. Additionally,