GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 Eldorado 🢒 Engine 🢒 Engine Controls - 4.6L 🢒 Cuts Out, Misses

Checks

Action

DEFINITION: Steady pulsation or jerking that follows engine speed, usually more pronounced as the engine load increases.

Preliminary
    • Refer to Important Preliminary Checks Before Starting in Symptoms .
    • Search for bulletins.
    • Check the intake air system for the following conditions:
       - Dirty or damaged air filter element
       - Restriction(s)

Sensor/System
    • Check MAF sensor and connections.
    • Check the engine coolant temperature (ECT) sensor for being shifted in value. Connect the scan tool and compare the engine coolant temperature with the intake air temperature 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. For specifications, refer to Temperature Versus Resistance .
    • Check TP sensor and connections.
    • Check for throttle body tampering, excessive deposits, or damage.
    • Check the EGR system for proper operation.

Fuel System
    • Check fuel pressure.
    • Check fuel injectors and related wiring.
    • Check for fuel in the fuel pressure regulator.
    • Check for items that can cause an engine to run rich and/or lean.
    • Check for contaminants in the fuel. Refer to Fuel Quality Diagnosis .

Ignition System
    • Check CKP sensors A and B for proper operation. Refer to DTC P1372 Crankshaft Position (CKP) Sensor A-B Correlation .
    • Check the IC circuits at each ignition module assembly for poor connections, damage, misrouting.
    • Check ignition coils for damage.
    • Check spark plug boots for misalignment, and damage.
    • Check for a damaged or missing ground spring at each ignition module assembly.

       Important: If the spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

    • Check the spark plugs for the following conditions:
       - Fouling
       - Cracks
       - Wear
       - Incorrect heat range or reach
       - Improper gap
       - Burned electrodes

Engine Cooling
    • Check the engine coolant level for being too low. Refer to Loss of Coolant in Engine Cooling.
    • Check for an incorrect, damaged, or malfunctioning thermostat. Refer to Thermostat Diagnosis in Engine Cooling.

Engine Mechanical
    • Check the following:
       - Engine compression, refer to Engine Compression Test in Engine Mechanical.
       - Sticking or leaking valves
       - Worn camshaft lobe(s)
       - Valve timing
       - Worn rocker arms
       - Broken valve springs
       - Excessive oil in the combustion chamber-leaking valve seals, refer to Oil Consumption Diagnosis in Engine Mechanical.
    • Check for incorrect basic engine parts. Inspect the following:
       - Camshaft
       - Cylinder heads
       - Pistons, etc.

Additional Checks
    • Visually/physically inspect the vacuum hoses for splits, kinks, proper routing and connections, and/or damage. Refer to the Vehicle Emission Control Information label.
    • Check the exhaust system for possible restrictions.
    • An engine misses condition can be caused by electromagnetic interference (EMI). EMI can usually be detected by monitoring the engine RPM with a scan tool. A sudden increase in RPM with little change in the actual engine RPM, indicates EMI is present.