Overview
The Engine Air System Verification Test is an automated test that helps in the troubleshooting of certain problems with the following systems: Clean Gas Induction System (CGI), combustion air supply and variable nozzle turbocharger. Table 1 lists the problems for each system.
| Systems and Problems | |
|---|---|
| System | Problems |
| CGI | Electrical problems with the circuit for the CGI control group |
| Low flow of CGI | |
| High flow of CGI | |
| Combustion Air Supply | Low flow of combustion air |
| High flow of combustion air | |
| Erratic flow of combustion air | |
| Variable Nozzle Turbocharger | Excessive turbocharger speed |
The problems that are listed in Table 1 can cause the following symptoms:
- Boost pressure may be incorrect
- The ARD may fail to ignite
- The ARD may experience a loss of combustion
- There may be high turbocharger speed on C7 engines or C9 engines
The test is performed when the vehicle is stationary and the engine is running. Approximately two minutes are required in order for the test to run. The Caterpillar Electronic Technician (ET) commands the following components to actuate during the test:
- CGI control group
- Air pressure control valve
- Variable nozzle turbocharger on C7 engines and C9 engines
Cat ET monitors the following sensors during the test:
- Differential pressure sensor for the CGI system
- Absolute pressure sensor for the CGI system
- Temperature sensor for the CGI system
- Differential pressure sensor for the combustion air system
- Intake manifold pressure sensor
- Turbocharger speed on C7 engines and C9 engines
Cat ET displays the results of the test after the test is complete. The test results must be interpreted in order to determine if troubleshooting is required.
Starting the Test
The test will not start until the following conditions are met:
- The vehicle must be stopped.
- The engine must be running.
- All engine driven accessories must be off.
- The coolant temperature must be above 65 °C (149 °F).
- Certain sensors and actuators do not have diagnostic codes.
The engine speed must be approximately 1400 rpm during the test. It may be necessary to manually raise the engine speed with the cruise control switches or the accelerator pedal. The test will abort for the following conditions:
- The user aborts the test.
- The vehicle speed is above zero.
- Engine speed is too high or too low.
- Engine load is excessive or inconsistent.
- Diagnostic codes for certain sensors and actuators
Ending the Test
The test ends automatically. The test results are displayed on Cat ET at the end of the test. The test results may be printed or the test results may be saved to a file on the hard disk. The file may be attached to a warranty report.
Test Points
The test is a series of test points. The test points are described in Table 2. Cat ET collects data for approximately 20 seconds at each test point. Then, Cat ET moves to the next test point.
| Test Points | ||||
|---|---|---|---|---|
| Test Point | System That is Being Tested | Position of the Component | ||
| 1 | "CGI Test" | The CGI valve is commanded to fully close | ||
| 2 | The CGI valve is commanded to open | |||
| 3 | "ARD Airflow Test" | The air pressure control valve is commanded to fully close | ||
| 4 | The air pressure control valve is commanded to open | |||
| 5 (1) | "Turbocharger Test" | The vanes for the turbine are commanded to fully open | ||
| 6 (1) | The vanes for the turbine are commanded to close | |||
| ( 1 ) | This test point is not performed on C13 engines and C15 engines. |
"CGI Test"
Opening the CGI control valve should cause the "CGI Venturi Mass Flow Rate" to increase between test point 1 and test point 2. There may be a slight decrease in "Boost Pressure" between test point 1 and test point 2. This is normal.
"ARD Airflow Test"
Opening the air pressure control valve should cause the "Aftertreatment 1 Secondary Mass Air Flow" to increase between test point 3 and test point 4. Opening the air pressure control valve should cause the "boost pressure" to decrease between test point 3 and test point 4.
"Turbocharger Test"
Closing the vanes for the turbine should cause the "boost pressure" and the "turbocharger 1 speed" to increase between test point 5 and test point 6.
Example of Test Results
The test results are displayed in metric units or English units. Settings on Cat ET determine if the results are in metric units or English units. Illustration 1 is an example of test results.
 | |
| Illustration 1 | g01433491 |
Example of test results | |
Acceptable Test Results
Cat ET collects "delivered fuel volume" data during the test. The data is not currently used for troubleshooting. Cat ET also calculates the difference between the test points. The differences are not currently used for troubleshooting.
C7 Engines
| Acceptable Test Results for C7 Engines | |||
|---|---|---|---|
| CGI Test | Test Point 1 | Test Point 2 | Difference (1) |
| Delivered Fuel Volume | |||
| CGI Venturi Mass Flow Rate | Maximum 1000 (2) Minimum 0 (2) |
Maximum 4481 (2) Minimum 1530 (2) |
|
| Boost Pressure | Maximum 66 kPa (9.6 psi) Minimum 25 kPa (3.6 psi) |
Maximum 63 kPa (9.2 psi) Minimum 19 kPa (2.7 psi) |
|
| ARD Airflow Test | Test Point 3 | Test Point 4 | |
| Delivered Fuel Volume | |||
| Boost Pressure | Maximum 69 kPa (10 psi) Minimum 27 kPa (3.9 psi) |
Maximum 46 kPa (6.6 psi) Minimum 18 kPa (2.6 psi) |
|
| Aftertreatment 1 Secondary Mass Air Flow | Maximum 16 (36) (3) Minimum 9 (19) (3) |
Maximum 180 (396) (3) Minimum 85 (188) (3) |
|
| Turbocharger Test | Test Point 5 | Test Point 6 | |
| Delivered Fuel Volume | |||
| Boost Pressure | Maximum 2 kPa (0.3 psi) Minimum 0 kPa (0 psi) |
Maximum 69 kPa (10 psi) Minimum 23 kPa (3.4 psi) |
|
| Turbocharger 1 Speed | Maximum 30483 rpm Minimum 14544 rpm |
Maximum 77781 rpm Minimum 49782 rpm |
|
| ( 1 ) | The values in this column are not currently used for troubleshooting. |
| ( 2 ) | These values do not have a unit of measurement. |
| ( 3 ) | This value is in kilograms per hour (pounds per hour). |
C9 Engines
| Acceptable Test Results for C9 Engines | |||
|---|---|---|---|
| CGI Test | Test Point 1 | Test Point 2 | Difference (1) |
| Delivered Fuel Volume | |||
| CGI Venturi Mass Flow Rate | Maximum 1182 (2) Minimum 0 (2) |
Maximum 4624 (2) Minimum 2918 (2) |
|
| Boost Pressure | Maximum 76 kPa (11.0 psi) Minimum 34 kPa (4.9 psi) |
Maximum 60 kPa (8.7 psi) Minimum 39 kPa (5.7 psi) |
|
| ARD Airflow Test | Test Point 3 | Test Point 4 | |
| Delivered Fuel Volume | |||
| Boost Pressure | Maximum 75 kPa (10.9 psi) Minimum 38 kPa (5.5 psi) |
Maximum 49 kPa (7.1 psi) Minimum 27 kPa (3.9 psi) |
|
| Aftertreatment 1 Secondary Mass Air Flow | Maximum 35 (78) (3) Minimum 0 (0) (3) |
Maximum 172 (379) (3) Minimum 130 (287) (3) |
|
| Turbocharger Test | Test Point 5 | Test Point 6 | |
| Delivered Fuel Volume | |||
| Boost Pressure | Maximum 0 kPa (0 psi) Minimum 0 kPa (0 psi) |
Maximum 72 kPa (10.4 psi) Minimum 47 kPa (6.8 psi) |
|
| Turbocharger 1 Speed | Maximum 25993 rpm Minimum 21421 rpm |
Maximum 67545 rpm Minimum 60512 rpm |
|
| ( 1 ) | The values in this column are not currently used for troubleshooting. |
| ( 2 ) | These values do not have a unit of measurement. |
| ( 3 ) | This value is in kilograms per hour (pounds per hour). |
C13 Engines
| Acceptable Test Results for C13 Engines | |||
|---|---|---|---|
| CGI Test | Test Point 1 | Test Point 2 | Difference (1) |
| Delivered Fuel Volume | |||
| CGI Venturi Mass Flow Rate | Maximum 1060 (2) Minimum 0 (2) |
Maximum 5826 (2) Minimum 3119 (2) |
|
| Boost Pressure | Maximum 25 kPa (3.7 psi) Minimum 11 kPa (1.6 psi) |
Maximum 20 kPa (3.0 psi) Minimum 8 kPa (1.2 psi) |
|
| ARD Airflow Test | Test Point 3 | Test Point 4 | |
| Delivered Fuel Volume | |||
| Boost Pressure | Maximum 25 kPa (3.7 psi) Minimum 11 kPa (1.7 psi) |
Maximum 17 kPa (2.5 psi) Minimum 7 kPa (1.1 psi) |
|
| Aftertreatment 1 Secondary Mass Air Flow | Maximum 18 (40) (3) Minimum 14 (32) (3) |
Maximum 98 (217) (3) Minimum 65 (144) (3) |
|
| ( 1 ) | The values in this column are not currently used for troubleshooting. |
| ( 2 ) | These values do not have a unit of measurement. |
| ( 3 ) | This value is in kilograms per hour (pounds per hour). |
C15 Engines
| Acceptable Test Results for C15 Engines | |||
|---|---|---|---|
| CGI Test | Test Point 1 | Test Point 2 | Difference (1) |
| Delivered Fuel Volume | |||
| CGI Venturi Mass Flow Rate | Maximum 1000 (2) Minimum 0 (2) |
Maximum 6800 (2) Minimum 3779 (2) |
|
| Boost Pressure | Maximum 26 kPa (3.7 psi) Minimum 10 kPa (1.5 psi) |
Maximum 18 kPa (2.6 psi) Minimum 3 kPa (0.4 psi) |
|
| ARD Airflow Test | Test Point 3 | Test Point 4 | |
| Delivered Fuel Volume | |||
| Boost Pressure | Maximum 26 kPa (3.7 psi) Minimum 11 kPa (1.6 psi) |
Maximum 19 kPa (2.7 psi) Minimum 7 kPa (1.1 psi) |
|
| Aftertreatment 1 Secondary Mass Air Flow | Maximum 29 (64) (3) Minimum 8 (18) (3) |
Maximum 105 (232) (3) Minimum 61 (135 lb) (3) |
|
| ( 1 ) | The values in this column are not currently used for troubleshooting. |
| ( 2 ) | These values do not have a unit of measurement. |
| ( 3 ) | This value is in kilograms per hour (pounds per hour). |
Unacceptable Test Results
Test results that are outside of the values that are indicated above should be investigated. The appropriate troubleshooting procedure for determining the root cause of the unacceptable test results is listed in Table 7.
| Appropriate Troubleshooting Procedure | ||||
|---|---|---|---|---|
| Test Point | System That is Being Tested | Troubleshooting Procedure | ||
| 1 | "CGI Test" | "Clean Gas Induction - Test" | ||
| 2 | ||||
| 3 | "ARD Airflow Test" | "ARD Combustion Air - Test" | ||
| 4 | ||||
| 5 (1) | "Turbocharger Test" | "Turbocharger - Test" | ||
| 6 (1) | ||||
| ( 1 ) | This test point is not performed on C13 engines and C15 engines. |
Additional troubleshooting information is located within the appropriate troubleshooting procedures.