Graph 6: Erratic Exhaust Gas Temperatures - Navistar MaxxForce DT Diagnostic Manual

4.6. GRAPH 6: ERRATIC EXHAUST GAS TEMPERATURES

1. Diesel Oxidation Catalyst Inlet
Temperature (DOCIT) (degrees
Fahrenheit) [Green]
2. Diesel Particulate Filter Inlet
Temperature (DPFIT) (degrees
Fahrenheit) [Orange]
Graph Analysis:
This graph shows erratic exhaust gas temperatures. Erratic temperatures in the exhaust stream occur when
the Diesel Oxidation Catalyst becomes contaminated, or an issue with the Aftertreatment Fuel Injector (AFI)
is present. This test does not give pass or fail results. It only allows the user to validate operation of the
aftertreatment system by monitoring exhaust gas temperatures.
Actions:
1. After Diesel Oxidation Catalyst (DOC) reaches operating temperature, verify Diesel Particulate
Filter Inlet Temperature (DPFIT) and Diesel Particulate Filter Outlet Temperature (DPFOT) signal
values do not fluctuate more than 50°F (28°C) within 2 minutes. In this graph, DPFIT and DPFOT
fluctuate more than 50°F (28°C) within 2 minutes.
Figure 10 Graph 6: Erratic Exhaust Gas Temperatures
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DIAGNOSTIC MANUAL
3. Diesel Particulate Filter Outlet
Temperature (DPFOT) (degrees
Fahrenheit) [Blue]
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