Troubleshooting - No Codes: Symptoms: Backfire

Check listed items in order as follows:

• Check Powertrain Control Module (PCM) power and ground circuits. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in appropriate SYSTEM & COMPONENT TESTING article.
• Check fuel pressure. See FUEL PRESSURE TEST under FUEL SYSTEMS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
• Check Manifold Absolute Pressure (MAP) sensor. See MANIFOLD ABSOLUTE PRESSURE SENSOR under ENGINE SENSORS & SWITCHES in appropriate SYSTEM & COMPONENT TESTING article.
• On models with 45RFE transmission, check minimum idle airflow. See MINIMUM IDLE AIRFLOW under IDLE CONTROL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article.