GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2000 🢒 Century (China) 🢒 Engine 🢒 Engine Controls - 2.5L (LB8) and 3.0L (L46) 🢒 Hard Start

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

Preliminary
    •  Refer to Intermittent Conditions before starting.
    •  Search for bulletins.

Sensor/System
    • Inspect the engine coolant temperature (ECT) sensor for being shifted in value. Connect a scan tool and compare the ECT with the intake air temperature (IAT) on a cold engine. The ECT and IAT should be within ± 3°C (5°F) of each other. Check the resistance of the ECT sensor if the temperature is out of range with the IAT sensor. Refer to Temperature Versus Resistance . If the ECT sensor resistance is not within the specification, refer to DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage or DTC P0113 Intake Air Temperature (IAT) Sensor Circuit High Voltage .
    • Inspect for 24X crankshaft position and camshaft position sensors on the scan tool. If both are not responding, inspect the sensor feed circuit.
    •  Inspect the mass air flow (MAF) sensor for proper installation and conditions. A MAF sensor with a damaged honeycomb may cause a hard start. Refer to Information Sensors/Switches Description .
    •  Using a scan tool, check the idle air control (IAC) operation. Refer to Idle Air Control (IAC) System Diagnosis .
    • Inspect the EGR system for proper sealing/connections and operation. Refer to Exhaust Gas Recirculation (EGR) System Description .

Fuel System
    • Inspect the fuel pump relay circuit for proper operation. Refer to Fuel Pump Electrical Circuit Diagnosis .
    • Inspect for low fuel pressure. Refer to Fuel System Pressure Test .
    • Inspect for fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

Ignition System
    • Inspect for proper ignition voltage output using the following steps:
       -  Clip the J 26792 spark tester to engine ground.
       -  Connect one end of a spark plug wire to the J 26792 spark tester. Leave the other end of the spark plug wire to the coil being tested.
       -  Connect one end of another spark plug wire to the other coil tower. Connect the other end of the spark plug wire to ground.
       -  Crank the engine while observing the J 26792 spark tester. A spark should be observed.
       -  Repeat the above steps for each coil.
    •  If spark is not present at the plugs, inspect for the following conditions:
       -  Inspect the coils for cracks, carbon tracking/arcing or a resistance value outside the specified range.

Coil Resistance
5K-7K ohms (5,000-7,000 ohms )

       -  Inspect the spark plug wires for signs of arcing/cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing or a resistance value outside the specified range.

Spark Plug Wire Resistance
1 968 ohms per meter (600 ohms per foot)

    Important: :  Spraying the secondary ignition wires with a light mist of water may help locate an intermittent problem. Ignition components will arc to ground when a secondary component is faulty.

       -  Defective module
       -  Ignition System Wiring--Loose ignition module feed or ground connection, or damaged system wiring
    •  Remove the spark plugs and inspect for the following:
       -  Fouled plugs
       -  Cracks
       -  Wear
       -  Improper gap
       -  Burned or damaged electrodes
       -  Improper heat range or reach
    •  If the spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

Engine Mechanical
    • Excessive oil in combustion chamber--Leaking valve seals. Refer to Base Engine Misfire Diagnosis in Engine Mechanical.
    •  Low cylinder compression--Refer to Engine Compression Test in Engine Mechanical.
    •  For incorrect basic engine parts inspect the following:
       -  Cylinder heads
       -  Camshaft and valve train components
       -  Pistons, etc.
       -  Refer to Base Engine Misfire Diagnosis in Engine Mechanical.