Additional Symptoms Tests: Surges/Chuggles

Inspect the heated oxygen sensors. The heated oxygen sensors should respond quickly to a change in throttle position. If the heated oxygen sensors do not respond to different throttle positions, inspect for contamination from fuel, silicon, or the incorrect use of RTV sealant. The sensors may have a white powdery coating and result in a high, but false, signal voltage, which gives a rich exhaust indication. The engine control module reduces the amount of fuel delivered to the engine, causing a driveability condition.

Hard Start

• Test the engine coolant temperature sensor. Compare the engine coolant temperature sensor value to the intake air temperature sensor value on a cold engine. The engine coolant temperature and intake air temperature sensor values should be within ± 3°C (5°F). If the engine coolant temperature sensor is out of range with the intake air temperature sensor, test the resistance of the engine coolant temperature sensor. Refer to Temperature Versus Resistance for resistance specifications. Replace the engine coolant temperature sensor if the resistance is not within specification. Refer to Engine Coolant Temperature Sensor Replacement . If the sensor is within the specification, test the engine coolant temperature circuits for a high resistance.
• Test the idle air control system.
• Verify that the fuel system has adequate pressure for engine start-up. With a scan tool, compare the Fuel Pressure Sensor parameter value to the Desired Fuel Pressure parameter value when the ignition key is first turned to ON. Refer to Fuel System Diagnosis  for additional information.

Hesitation, Sag, Stumble

• Test the fuel pressure. Refer to Fuel System Diagnosis .
• Test the manifold absolute pressure sensor. Refer to DTC P0106 .
• Test the generator. Refer to Symptoms - Engine Electrical . Repair the charging system if the generator output voltage is less than 9 volts or more than 16 volts.

Poor Fuel Economy

• Heavy loads being carried or towed.
• Acceleration rate too much or too often.
• Inspect for foreign material accumulation in the throttle bore, and for carbon deposits on the throttle plate and shaft. Also inspect for throttle body tampering.