Cuts Out, Misses. Oldsmobile Shelby Series 1 1999

For 1990-2009 cars

Checks | Action
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DEFINITION: A steady pulsation or jerking that follows engine speed, which is usually more pronounced as the engine load increases. This condition is not normally felt above 1,500 RPM or 48 km/h (30 mph). The exhaust has a steady spitting sound at idle or at low speed.

Preliminary

• | Refer to Important Preliminary Inspections Before Starting in Symptoms .

• | Search for bulletins.

• | Inspect the PCM grounds for being clean, tight, and in the proper locations. Refer to Engine Controls Schematics .

• | Remove the air filter element and inspect for dirt or for being restricted. Refer to Air Filter Element Service . Replace if necessary.

Fuel System

• | Test the fuel injectors. Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) .

• | Test for proper fuel pressure. Refer to Fuel System Diagnosis .

• | Test for a restricted fuel filter. Refer to Fuel System Diagnosis .

• | Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

• | Inspect the items which can cause an engine to run rich. For a rich condition, refer to DTC P0132 HO2S Circuit High Voltage Bank 1 Sensor 1 and DTC P0152 HO2S Circuit High Voltage Bank 2 Sensor 1 .

• | Inspect items that can cause an engine to run lean. For a lean condition, refer to DTC P0131 HO2S Circuit Low Voltage Bank 1 Sensor 1 and DTC P0151 HO2S Circuit Low Voltage Bank 2 Sensor 1 .

Sensor/System | Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity. Refer to Knock Sensor (KS) System Description .

Ignition System

• | Wet down the secondary ignition system with water from a spray bottle. Wetting down the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply water.

• | Test for proper ignition voltage output with the J 26792 spark tester.

• | Remove the spark plugs and inspect for the following conditions:

- | Correct heat range

- | Wet plugs

- | Cracks

- | Wear

- | Improper gap

- | Burned electrodes

- | Heavy deposits

• | An improper spark plug gap will cause a driveability concern. Gap the spark plugs using a wire gauge gap tool.

• | Determine the cause of the fouling before replacing the spark plugs if the spark plugs are gas, coolant or oil fouled. Refer to DTC P0172 Fuel Trim System Rich Bank 1 or DTC P0175 Fuel Trim System Rich Bank 2 for diagnosis of the rich condition. Refer to Spark Plug Visual Diagnosis for diagnosis of coolant or oil fouled spark plugs.

• | Visually and physically inspect the secondary ignition for the following:

- | Ignition wires arcing to ground

- | Ignition wires for proper routing

- | Ignition coils for cracks or carbon tracking

Engine Mechanical

• | Inspect engine mechanical for the following:

- | Test compression

- | Sticking or leaking valves

- | Worn camshaft lobes

- | Valve timing

- | Bent push rods

- | Worn rocker arms

- | Broken valve springs

- | Excessive oil in combustion chamber-Leaking valve seals

• | For incorrect basic engine parts, inspect the following components:

- | Camshaft

- | Cylinder heads

- | Pistons, etc.

Additional Checks

• | Inspect the following exhaust system components for possible restrictions:

- | The exhaust system for physical damage

- | The exhaust manifold for a collapsed inner wall

- | The mufflers for heat distress or possible internal failure

- | The three-way catalytic converters (TWC) for possible plugged pipes by comparing the exhaust system back pressure on each side of engine

• | Electromagnetic interference (EMI) on the reference circuit can cause an engine miss condition. A sudden increase in RPM with little change in actual engine RPM change indicates that EMI is present. Inspect for high voltage components near the ignition control circuits if a condition exists.

• | Inspect the intake manifold and the exhaust manifold passages for casting flash.