temperature, which may cause damage to the three-way catalytic converter. To prevent these increases in emissions and to limit the possibility of
thermal damage, the ECM monitors the misfire count. When the temperature of the three-way catalytic converter reaches the point of thermal
degradation, the ECM blinks the MIL. To monitor misfires, the ECM uses both the VVT sensor and the crankshaft position sensor. The VVT sensor
is used to identify any misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. Misfires
are counted when the crankshaft rotation speed variations exceed predetermined thresholds.
If the misfire count exceeds the threshold level and could cause emission deterioration, the ECM illuminates the MIL and sets a DTC.
When DTCs for misfiring cylinders are randomly set, but DTC P0300 is not set, it indicates that misfires have been detected in different cylinders at
different times. DTC P0300 is only set when several misfiring cylinders are detected at the same time.
MONITOR DESCRIPTION
Text in Illustration
- The ECM illuminates the MIL and sets a DTC when either one of the following conditions, which could cause emission deterioration, is
detected (2 trip detection logic).
- Within the first 1000 crankshaft revolutions of the engine starting, an excessive misfiring rate (approximately 20 to 50 misfires per 1000
crankshaft revolutions) occurs once.
- After the first 1000 crankshaft revolutions, an excessive misfiring rate (approximately 20 to 60 misfires per 1000 crankshaft revolutions)
occurs 4 times in sequential crankshaft revolutions.
- The ECM flashes the MIL and sets a DTC when either one of the following conditions, which could cause the three-way catalytic converter
damage, is detected (2 trip detection logic).
- In every 200 crankshaft revolutions at a high engine speed, the threshold misfiring percentage is recorded once.
- In every 200 crankshaft revolutions at a normal engine speed, the threshold misfiring percentage is recorded 3 times.
Misfire Monitor for Mexico Models
The ECM illuminates the MIL and sets a DTC when either one of the following conditions, which could cause emission deterioration, is detected (2
trip detection logic).
- Within the first 1000 crankshaft revolutions of the engine starting, an excessive misfiring rate (approximately 1000 misfires per 1000
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