Circuit Description

Misfire is detected using Camshaft Position (CMP) and Crankshaft Position (CKP) sensors. When PCM senses CKP deceleration not associated with normal engine speed reduction, CMP is used to determine misfiring cylinder. PCM determines misfires on each cylinder and evaluates a random misfire and set DTC.

Conditions required to set code are:

• No transaxle or VSS DTCs set.
• No CKP, CMP, ECT, MAF or TP sensor DTCs set.
• Engine speed 450-5800 RPM.
• ECT 19-248°F (-7 to 120°C).
• Throttle steady.
• PCM detects crankshaft RPM variation, indicating a misfire which could cause catalytic convertor damage or high emissions.