Engine Hesitates Or Accelerates Poorly

Check Clutch Operation Or Brakes

• Ensure parking brake does not drag when released.
• Ensure service brakes do not drag when released.
• Check for clutch-slip and adjust as necessary.

Check Sensors

• Check upstream HO2S.
• Check Throttle Position (TP) sensor.
• Check Engine Coolant Temperature (ECT) sensor.
• Check Manifold Absolute Pressure/Intake Air Temperature (MAP/IAT) sensor.
• Check Mass Airflow (MAF) sensor.
• Check Knock Sensor (KS).

Check For Air Leaks

• Check vacuum and purge hoses, connections and related components.
• Check intake manifold and throttle body.
• Check for leaks in exhaust system.

Check Fuel Supply

• Check for a dirty or clogged air filter.
• Check for contaminated fuel.
• Ensure there is enough fuel.
• Check for restricted fuel filter.
• Ensure fuel pump is operating properly.
• Ensure fuel pressure is correct.
• Ensure fuel pressure regulator is operating properly.
• Check fuel lines for leaks and/or deformations.
• Ensure fuel injectors are operating properly.

Check ECM Harness Connectors

• Check ECM power and ground circuits.
• Check sensor power, ground and signal circuits.
• Ensure ECM control relay is operating properly.

Check Ignition Spark

• Check power and ground circuits for ignition coils.
• Ensure ignition coils are operating properly.
• Ensure spark plug gap is correct and plugs are not fouled.
• Check spark plug cables.

Check Engine Idle Speed

• Ensure engine idle speed is correct.
• Ensure engine idle speed actuator is operating properly.
• Ensure ignition timing is correct.

If no other problems are found, replace ECM and recheck.