Well, sort of. If you replicate the situation three separate times and the misfire monitor passes each time, the CEL will extinguish and the code will clear from history. However, if the situation is not replicated or monitor does not pass, the CEL will stay in history for 80 drive cycles. I hope that's not too confusing, but the ECM has to be very careful in dealing with misfire due to CARB regulations, so it makes the monitoring and the rules of it all very difficult.kinkyllama wrote:Wait so Chip, if you turn off the key three times the code isnt stored anymore?
This is exactly right. There is a hall effect sensor that is "looking" at the teeth of the timing belt pulley on the crank. The ECM has a baseline map of what the signature of these teeth looks like. While the crank is spinning, the ECM is monitoring the real-time map and comparing it to the baseline. If the ECM detects enough of a deviation from the baseline map then it is reported as a misfire. If there are enough misfires in a given period of time the ECM will light the CEL. If there are a severe amount of misfires in that time period the CEL will blink, indicating what the ECM interprets as catalyst damaging misfire. My thought is that the UD pulley disrupts the balance of the crankshaft at very high speeds, causing vibration of the crank that the ECM sees as misfire at the timing belt pulley teeth. Hope this helps explain the misfire monitoring and how difficult it is to monitor and how easy it is to disrupt it.as i understand the crank position sensor got nothing to do with the UD pully, the sensor detects crank motion from the sproket gear at the back of the pully not the pully itself.
-Chip