Rough, Unstable, or Incorrect Idle and Stalling. Cadillac Seville 2000

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2000 🢒 Seville 🢒 Engine 🢒 Engine Controls - 4.6L 🢒 Rough, Unstable, or Incorrect Idle and Stalling

Checks

Action

DEFINITION: Engine runs unevenly at idle. If severe, the engine or vehicle may shake. Engine idle speed may vary in RPM. Either condition may be severe enough to stall the engine.

Preliminary

•	Refer to Important Preliminary Checks Before Starting in Symptoms .

•	Search for bulletins.

Sensor/System

•	Check the PCV system for proper operation.

•	Check the throttle body, and TP sensor for proper operation and damage.

•	Check the knock system (KS) for excessive spark retard.

•	Check the EGR system for proper operation.

•	Check the IAC valve and valve housing for deposits and/or damage.

•	Check for dirty or damaged air cleaner element.

•	Check for collapsed or damage intake air ducting.

Fuel System

•	Check the fuel pressure. Refer to Fuel System Pressure Test .

•	Check the fuel injectors and related wiring. Refer to the following:

-	Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 .

-	Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) .

-	Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Outside 10-35 Degrees C (50-95 Degrees F) .

•	Check the minimum idle speed.

•	Check for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Check for items that cause the engine to run rich, or lean.

Ignition System

•	Check the IC circuits for proper connections at each ignition module assembly.

•	Check for proper ignition voltage output using the spark tester J 26792.

•	Check the ignition coils for cracks, or damage.

•	Check for a missing or damaged ignition module assembly grounding spring.

•	Check for misaligned, or damaged spark plug boots.

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

-	Improper heat range or reach

-	Incorrect gap

Engine Mechanical

•	Check the following:

-	Engine compression

-	Sticking or leaking valves

-	Worn camshaft lobes

-	Valve timing

-	Worn rocker arms

-	Broken or weak valve springs

-	Excessive oil in the combustion chamber-leaking valve seals.

•	Check for incorrect basic engine parts. Inspect the following:

Camshafts

-	Cylinder heads

-	Pistons, etc.

Additional Checks

•	Check the exhaust system for possible restrictions.

•	Check for fuel loading in the EVAP system.