For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

DTC P0300 00: Engine Misfire Detected
DTC P0301 00: Cylinder 1 Misfire Detected
DTC P0302 00: Cylinder 2 Misfire Detected
DTC P0303 00: Cylinder 3 Misfire Detected
DTC P0304 00: Cylinder 4 Misfire Detected
DTC P0313 00: Misfire Detected With Low Fuel Level

### Circuit/System Description

The engine control module (ECM) uses information from the crankshaft position sensor in order to determine when an engine misfire is occurring and uses information from the camshaft position sensor - intake and camshaft position sensor - exhaust sensors in order to determine which cylinder is misfiring. By monitoring variations in the crankshaft rotation speed for each cylinder, the ECM is able to detect individual misfire events. If the ECM detects a misfire rate sufficient to cause emission levels to exceed mandated standards, DTC P0300 00 sets. Under certain driving conditions, a misfire rate can be high enough to cause the 3-way catalytic converter to overheat, possibly damaging the converter. The malfunction indicator lamp (MIL) will flash ON and OFF when converter overheating, damaging conditions are present and DTC P0300 00 is set. DTCs P0301-P0304 00 correspond to cylinders 1-4. If the ECM is able to determine that a specific cylinder is misfiring, the DTC for that cylinder will set. If the ECM detects a misfire and low fuel level, DTC P0313 00 is set.

### Conditions for Running the DTC

• | DTCs P0016 00, P0121 00, P0122 00, P0123 00, P0221 00, P0222 00, P0223 00, P0335 00 or P0336 00 are not set.

• | The engine speed is between 600-6528 RPM.

• | The ECM is not in fuel cut-off mode.

• | DTCs P0300 00, P0304 00, and P0313 00 run continuously when the above conditions are met.

### Conditions for Setting the DTC

The ECM is detecting a crankshaft rotation speed variation indicating a misfire sufficient to cause emission or catalytic converter damaging levels to exceed mandated standards.

### Action Taken When the DTC Sets

DTCs P0300 00-P0304 00 and P0313 00 are Type B DTCs.

### Conditions for Clearing the DTC

DTCs P0300 00-P0304 00 and P0313 00 are Type B DTCs.

### Diagnostic Aids

• | A misfire may only occur when the engine is under a load or when the engine is cold.

• | A misfire DTC may be caused by an excessive vibration from sources other than the engine. Inspect for the following possible sources:

⇒ | A tire or wheel that is out of round or out of balance

⇒ | Variable thickness brake rotors

⇒ | Certain rough road conditions

⇒ | A damaged accessory drive component or belt

⇒ | A damaged reluctor wheel

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

#### Special Tools

J 36012-A Ignition System Diagnosis Harness

EL-26792 HEI Spark Tester

For equivalent regional tools, refer to Special Tools.

### Circuit/System Verification

1. Verify that no other DTCs are set.

⇒ | If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.

2. Engine idling, verify there is no abnormal engine noise.

⇒ | If there is abnormal engine noise, refer to Symptoms - Engine Mechanical.

3. If the vehicle passes the circuit/system verification test, operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the freeze frame/failure records lists.

### Circuit/System Testing

1. Verify that the following conditions do not exist:

• | Low fuel level

• | Engine vacuum leaks

• | Fuel pressure that is too low or too high--Refer to Fuel System Diagnosis.

• | Contaminated fuel--Refer to Alcohol/Contaminants-in-Fuel Diagnosis.

• | Restricted exhaust system--Refer to Restricted Exhaust.

⇒ | If you find any of the above conditions, repair as necessary.

2. Ignition OFF, disconnect the harness connector from the K35 Ignition Control Module (ICM).
3. Remove the K35 Ignition Control Module (ICM) from the engine.
4. After removing the K35 Ignition Control Module (ICM) from the engine, connect the engine wire harness to the K35 Ignition Control Module (ICM).
5. Install the J 36012-A Ignition System Diagnosis Harness onto each spark plug and secure the ends into the K35 Ignition Control Module (ICM) spark plug boots for testing.
6. Install a EL-26792 HEI Spark Tester into the position #1 of the K35 Ignition Control Module (ICM) and ground.

Note: An erratic or weak spark is considered a no spark condition.

7. Crank the engine and observe the EL-26792 HEI Spark Tester . The spark tester should spark.
8. Ignition OFF, remove the spark tester and repeat the test for each cylinder.

⇒ | If there is no spark, refer to Electronic Ignition (EI) System Description for diagnosis of the K35 Ignition Control Module (ICM).

9. Ignition OFF, inspect each spark plug. If there is a condition with the spark plug, replace the spark plug. Refer to Ignition System Specifications and Spark Plug Inspection.

### Repair Instructions

• | Ignition Coil Replacement

• | Spark Plug Replacement

### Repair Verification

1. Install any components or connectors that have been removed or replaced during diagnosis.
2. Perform any adjustment, programming or setup procedures that are required when a component or module is removed or replaced.
3. Clear the DTCs.
4. Turn OFF the ignition for 60 s.
5. If the repair was related to a DTC, duplicate the conditions for running the DTC and use the freeze frame/failure records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to the Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure.
6. To verify that the performance of the catalytic converter has not been affected by the condition that set this DTC, perform the Repair Verification for DTC P0420 00. Refer to DTC P0420.