GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2003 🢒 Seville 🢒 Engine 🢒 Engine Controls - 4.6L 🢒 Hard Start

Inspection/Test

Action

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

Preliminary
    • Refer to Important Preliminary Checks Before Starting in Symptoms - Engine Controls .
    • Search for bulletins.

Sensor/System
    • Inspect the engine coolant temperature (ECT) sensor for being shifted in value. Install the scan tool and compare the displayed engine coolant temperature with the intake air temperature on a cold engine. Check the resistance of the ECT sensor if the engine coolant temperature is not within ±3°C (5°F) of intake air temperature (IAT). Refer to Temperature Versus Resistance . If the ECT sensor resistance is not within the specification, refer to DTC P0117 or DTC P0118 .
    • Inspect the mass air flow (MAF) sensor and connections.
    • Inspect the operation of the idle air control (IAC) valve. Refer to Idle Air Control (IAC) System Diagnosis
    • Using the scan tool, monitor the throttle position (TP) sensor voltage. The TP sensor voltage should be less than 0.9 volts with a closed throttle. If the TP sensor voltage is more than 0.9 volts, inspect the throttle body and accelerator cables for binding.
    • Inspect for the proper operation of the exhaust gas recirculation (EGR) system. Refer to Exhaust Gas Recirculation (EGR) System Description

Fuel System
    • Inspect the operation of the fuel pump. The pump should turn ON for approximately 2 seconds when the ignition is turned ON. Refer to Fuel Pump Electrical Circuit Diagnosis
    • Inspect for incorrect fuel pressure. Refer to Fuel System Diagnosis .
    • Inspect the fuel injectors and related fuses. Refer to Fuel Injector Solenoid Coil Test , and Fuel Injector Balance Test with Tech 2 or Fuel Injector Balance Test with Special Tool .
    • Test for fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

Ignition System
    • Inspect the operation of crankshaft position (CKP) sensors A and B.
    • Test for proper ignition voltage output using the J 26792 Spark Tester .
    • Inspect for damaged ignition coils within the ignition coil module assemblies.
    • Inspect for damaged or misaligned spark plug boots.
    • Inspect for a missing or damaged ignition module ground spring.
    • Inspect the spark plugs. Refer to Spark Plug Inspection .

Engine Mechanical
    • Excessive oil in combustion chamber-leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical 4.6L.
    • Inspect for low cylinder compression. Refer to Engine Compression Test in Engine Mechanical 4.6L.
    • Inspect the following for incorrect or damaged basic engine parts:
       - Cylinder heads
       - Camshaft and valve train components
       - Pistons, and piston assemblies