CAMSHAFT AS 20R1141 - Caterpillar

Start the engine. Before continuing, allow the engine to warm to normal operating temperature.
Use an emissions analyzer to check the emissions level of the engine exhaust. Measure the O2, CO, and NOX at the inlet and outlet of the converter. Record the data.Note: Ensure that the readings from the analyzer have stabilized prior to recording the data.Use the information in Table 1 to troubleshoot the performance of the catalytic converter.
Table 1
Catalyst Performance Matrix
Problem Probable Cause Corrective Action
Reduced exhaust system back-pressure
Elevated emissions levels Damaged catalyst substrate caused by excess vibration or engine backfire Perform the necessary repairs on the engine.
Replace the catalyst substrate.
Elevated catalytic converter temperatures
Excessive emissions levels Ignition and/or plugs failure
Detonation Check the engine timing.
Check the heating values of the fuel.
O2 level is greater than 0.5 percent at the inlet of the converter Exhaust leak Check the exhaust system for leaks.
Ensure that the crankcase ventilation system is operating according to the manufacturers specifications.
O2 level is greater than 0.5 percent at the inlet of the converter
CO level is greater than 7000 ppm at the inlet of the converter
Normal catalytic converter temperatures Leaking exhaust valves. Check the condition of the engine exhaust valves.
O2 level is greater than 0.5 percent at the inlet of the converter
CO level is greater than 7000 ppm at the inlet of the converter
Elevated catalytic converter temperatures Ignition misfire Perform the necessary repairs to the engine.
O2 level is greater than 0.5 percent at the inlet of the converter
CO level is less than 7000 ppm at the inlet of the converter
Reduced catalytic converter temperatures
Erratic swings in the O2 sensor output. Low compression ratio or low load condition Perform the necessary repairs to the engine.
CO levels are low at the outlet of the catalytic converter
NOX levels are high at the outlet of the catalytic converter
Normal engine operation Incorrect air/fuel ratio
A damaged catalytic coating can cause a loss in the capacity for the storage of oxygen.
This condition is probably caused by high exhaust temperatures that are caused by ignition misfire. Correct the problem that is causing the incorrect air/fuel ratio.
CO levels are high at the outlet of the catalytic converter
NOX levels are low at the outlet of the catalytic converter
Normal engine operation Improper air/fuel ratio
A damaged catalytic coating can cause a loss in the capacity for the storage of oxygen.
This condition is probably caused by high exhaust temperatures that are caused by ignition misfire. Repair the engine ignition system.
Replace catalyst substrate.
CO levels are high at the outlet of the catalytic converter
NOX levels are high at the outlet of the catalytic converter
Normal air/fuel ratio control operation
Normal engine operation This condition is probably due to damage to the catalytic coating on the substrate. A damaged catalytic coating can cause a loss in the capacity for the storage of oxygen. Perform any repairs that are necessary for the engine.
Replace catalyst substrate. Perform the repairs that are necessary.For additional information related to the catalytic converter, refer to the following information:Reference: Systems Operation, "Catalytic Convertor"Reference: Testing and