SPN 1324, FMI 31 - Emissions/Catalyst Damage Misfire Detected Cylinder #2
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Cylinder #2 Misfire Detected-Emissions/Catalyst Damaging Check Condition- Key On, Engine Running Fault Condition- Misfire occurrences higher than allowed for each operating condition calibrated at a level that can result in catalyst damage Corrective Action(s)- Illuminate MIL and/or sound audible warning or illuminate secondary warning lamp, disable adaptive learn fueling correction for key-cycle, and disable closed-loop fueling correction during active fault. Emissions related fault
The ECU is capable of detecting combustion misfire for certain crank-cam software modules. The ECU continuously monitors changes in crankshaft angular velocity, comparing acceleration rates on a cycle-to-cycle basis and determining if a given cylinder’s rate of change is abnormal compared to other cylinders. This method of detection is better known as Instant Crank Angle Velocity (ICAV). Misfire is of concern for four main reasons: 1) damage can occur to aftertreatment systems due to the presence of unburned fuel and oxygen causing chemical reactions resulting in extremely high temperatures causing irreversible damage to catalytic coatings and/or substrates, 2) exhaust emissions increase during misfiring, 3) the engine’s driveability suffers due to inconsistent operation, and 4) fuel economy suffers due to the need for higher power operating conditions to achieve the same brake torque. The GCP has two stages of misfire faults 1) emissions/catalyst damaging misfire detected and 2) driveability or general misfire detected. Emissions/catalyst misfire is generally thought of as a per “bank” fault as multiple cylinders misfiring on the same bank cumulatively add unburned fuel and oxygen to that banks aftertreatment device(s). The catalyst/emissions fault is configured to set based on one or both of the following conditions: 1) Aftertreatment temperatures experienced during this level of misfire are high enough to cause permanent damage to emission control components Indmar Products
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