Cuts Out, Misses. Chevrolet Metro 1998

For 1990-2009 cars

Checks | Action
--- | ---
DEFINITION: A steady pulsation or jerking that follows engine speed, usually more pronounced as the engine load increases. The exhaust has a steady spitting sound at idle, low speed or on hard acceleration.

Preliminary Checks

• | Refer to Powertrain On Board Diagnostic (OBD) System Check .

• | Refer to Symptoms .

Ignition System Checks

Check for an ignition system misfire:

Important: DO NOT perform this test for more than 2 minutes in order to prevent damage to the catalytic converter.

1. Start the engine.
2. Disconnect one fuel injector (electrical connector) at a time while observing engine RPM.
3. An equal RPM drop on all cylinders (within 50 RPM) indicates a common condition. Refer to Rough, Unstable, or Incorrect Idle and Stalling .
4. No RPM drop on one or more cylinders indicates a cylinder specific condition. Check for spark on the suspected cylinder(s) with a J 26792 spark tester or equivalent.
5. If there is no spark, Refer to Engine Cranks but Does Not Run .
6. If there is spark, check the spark plugs for any of the following conditions:

- | Wet (fuel fouled) plugs.

- | A terminal screw that is bent or loose (rotate and pull).

- | A ceramic insulator that has cracks, carbon tracking or deposits (red or black dust)

- | A tip insulator that has cracks, carbon tracking, deposits (oil, carbon, glazing, fuel additive), or is loose (rattles).

- | A center electrode that is loose (wiggles side to side)

- | An incorrect spark plug gap that is too large or too small.

7. If the ignition system components of the suspect cylinder pass all checks, inspect the cylinder for mechanical or fuel delivery faults.

• | Check that the spark plug wire resistance does not exceed 30,000 ohms.

• | Check the ignition system for moisture, dust, cracks, burns, etc.

• | Run the engine and spray the secondary ignition system with water in order to check for secondary voltage shorts.

• | Check the CKP sensor engine reference signal with a scan tool. Observe the Engine Speed parameter while operating the engine at the speed of the concern. The scan tool should indicate steady and linear RPM readings while running. If the erratic values, such as sudden spikes or drops in engine speed are displayed, the engine reference signal is not stable enough for the engine to run properly. Check for a short to ground in the CKP sensor Ignition Reference Low circuit . A short to ground in the CKP sensor Ignition Reference Low circuit will cause a faulty engine reference signal to be sent to the PCM, but will not set a CKP sensor DTC (P0335).

Engine Mechanical Checks

• | Check for any of the following engine mechanical problems:

- | Incorrect valve lash

- | Broken or weak valve springs

- | Incorrect valve timing

- | Incorrect or worn camshaft

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

• | Refer to Engine Mechanical.

Fuel System Checks

• | Check for a restriction in the fuel supply system. Check for the correct fuel pressure. Refer to Fuel System Diagnosis .

• | Check the fuel injectors. Perform the Fuel Injector Coil Test Procedure and the Fuel Injector Balance Test Procedure. Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) and Sequential Multiport Fuel Injector Balance Test .

• | Check for water contamination of the fuel.

Additional Checks

• | Check the PCM grounds for being clean, tight, and in their proper locations. Refer to PCM Power and Ground electrical schematic.

• | Check the Service Bulletins for any updates or information.