DTC P0300 - ENGINE MISFIRE DETECTED GMC Envoy I

Note. For circuit reference, see WIRING DIAGRAMS - 4.3L article.

Circuit Description

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

Conditions for setting DTC

1. No CKP, IAC, MAF, TP or VSS sensor DTCs set.
2. Rough road not detected.
3. Engine speed 300-5600 RPM.
4. ECT at normal operating temperature.
5. System voltage 9-16 volts.
6. Positive or negative throttle position change is less than 2.9 percent for 100 msec.
7. A misfire is detected.