Engine Controls - Trouble Shooting - No Codes - 3.4L: Symptoms: Backfires: Sensor/System

Inspect for the following intermittent ignition system conditions:

• Monitor the 24X crank sensor and the CMP sensor signal present parameters on the scan tool. If both are not responding, test the sensor feed circuit. Both sensors use a separate feed circuit but are internally connected to power. Check all CKP sensor "A" and CMP sensor circuits for intermittents.
• Monitor the 3X parameter on the scan tool. If the 3X is not responding, inspect the CKP sensor "B" and circuits for intermittents. Inspect the Ignition Control (IC) circuit, IC timing control circuit, low resolution engine speed signal circuit and the low reference circuit for intermittents. If these circuits become open, or shorted, they may not set a Diagnostic Trouble Code (DTC) immediately, but are capable of causing driveability complaints.
• Check the CKP sensor "B" for an internal short.

Inspect the Mass Airflow (MAF) sensor conditions. Ensure that the MAF sensor honeycomb is not damaged.