Poor Fuel Economy

Check listed items as follows:

• Check Powertrain Control Module (PCM) power and ground circuits. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in SYSTEM & COMPONENT TESTING article.
• Check fuel pressure. See FUEL PRESSURE TEST under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES article.
• Check engine coolant temperature sensor. See CHECKING ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
• Check throttle position sensor. See CHECKING THROTTLE POSITION SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
• On models with 45RFE transmission, check minimum idle airflow. See CHECKING MINIMUM AIRFLOW under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
• Check idle air control motor operation. See CHECKING IDLE AIR CONTROL MOTOR under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
• Check EVAP emission system. See FUEL EVAPORATIVE SYSTEM in SYSTEM & COMPONENT TESTING article.
• Check intake air temperature sensor. See CHECKING INTAKE AIR TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.