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Old 01-02-2013, 09:52 AM   #4
Cobb Tuning
Member#: 4803
Join Date: Mar 2001
Location: Austin, TX

Yes, the roughness monitor is a misfire count (per cylinder). The ECU determines misfires by basically looking for unusual variations in RPM. There are certain variable thresholds that determine the level of misfire counts before a check engine light code is set so it is possible to have perceived misfires without a DTC if the level is low enough.

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