GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2004 🢒 Optra 🢒 Engine 🢒 Engine Controls - 1.4L DOHC 🢒 Hard Start

Hard Start

Checks

Action

DEFINITION: Engine cranks OK, but does not start for a long time. The vehicle does eventually run, or may start but immediately stalls.

Preliminary
    • Refer to Important Preliminary Checks Before Starting in Symptoms - Engine Controls .
    • Verify that the engine control module (ECM) grounds are clean, tight, and in the correct locations.
    • Search for bulletins.

Sensor/System

Inspect the engine coolant temperature (ECT) sensor. Compare the ECT sensor value to the intake air temperature (IAT) sensor value on a cold engine. The ECT and IAT sensor values should be within ± 3°C (5°F). If the ECT sensor is out of range with the IAT sensor, test the resistance of the ECT sensor. Refer to Temperature Versus Resistance for resistance specifications. Replace the ECT sensor if the resistance is not within specification. Refer to Engine Coolant Temperature Sensor Replacement . If the sensor is within the specification, test the ECT circuits for a high resistance.

Fuel System
    • Test the fuel pump relay operation. The fuel pump should turn ON for 2 seconds when the ignition is turned ON. Refer to Fuel Pump Electrical Circuit Diagnosis .
    • Test for incorrect fuel pressure. Refer to Fuel System Diagnosis .
    • Test for leaking fuel injectors. Refer to Fuel System Diagnosis .
    • Test for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

Ignition System
    • Test the ignition voltage output with the J 26792 Spark Tester. Refer to Electronic Ignition (EI) System Diagnosis .
    • Remove the spark plugs and inspect for the following conditions:
       - Incorrect heat range
       - Wet plugs
       - Cracks
       - Excessive wear
       - Improper gap
       - Burned electrodes
       - Heavy deposits
       - Refer to the following procedures:
    • If the spark plugs are fouled by gas, coolant, or oil, determine the cause before replacing the plugs. Refer to the following procedures:
       - For diagnosis of a rich condition, refer to DTC P0172 .
       - For diagnosis of coolant or oil fouled spark plugs, refer to Loss of Coolant in Engine Cooling or Symptoms - Engine Mechanical in Engine Mechanical - 1.4L DOHC.
    • Inspect the spark plug wires for damage. Refer to Spark Plug Wire Replacement .
    • Inspect the ignition coil for cracks or carbon tracking.

Engine Mechanical
    • Inspect for excessive oil in the combustion chamber and for leaking valve seals.
    • Test for low cylinder compression. Refer to Engine Compression Test in Engine Mechanical - 1.4L DOHC.
    • Inspect the combustion chambers for excessive carbon buildup. Clean the chambers with top engine cleaner. Follow the instructions on the can.
    • Inspect the following for incorrect basic engine parts:
       - The cylinder heads
       - The camshaft
       - The pistons, connecting rods, and bearings
       - Refer to the following procedures in Engine Mechanical - 1.4L DOHC: