GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2002 🢒 DeVille 🢒 Engine 🢒 Engine Controls - 4.6L 🢒 Hard Start

Checks

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
    • Check 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. 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.
    • Check the operation of the idle air control (IAC) valve.
    • 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.
    • Check for the proper operation of the exhaust gas recirculation (EGR) system.

Fuel System
    • Check the operation of the fuel pump. The pump should turn ON for approximately 2 seconds when the ignition is turned ON.
    • Check for incorrect fuel pressure. Refer to Fuel System Diagnosis .
    • Check 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 .
    • Check for fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

Ignition System
    • Check the operation of crankshaft position sensors A and B.
    • Check for proper ignition voltage output using the spark tester J 26792 .
    • Check for damaged ignition coils within the ignition coil module assemblies.
    • Check for damaged or misaligned spark plug boots.
    • Check for a missing or damaged ignition module ground spring.
    • Check 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.
    • Check for low cylinder compression. Refer to Engine Compression Test in Engine Mechanical
    • Check for incorrect or damaged basic engine parts. Inspect the following:
       - Cylinder heads
       - Camshaft and valve train components
       - Pistons, and piston assemblies