P0303

On Board Diagnosis Logic
If a misfire occurs, the engine speed will fluctuate. If the fluctuation is detected by the crankshaft position sensor (OBD), the misfire is diagnosed.
The misfire detection logic consists of the following two conditions.

1. One Trip Detection Logic (Three Way Catalyst Damage)
When a misfire is detected which will overheat and damage the three way catalyst, the malfunction indicator lamp (MIL) will start blinking; even during the first trip. In this condition, ECM monitors the misfire every 200 revolutions.
If the misfire frequency decreases to a level that will not damage the three way catalyst, the MIL will change from blinking to lighting up.
(After the first trip detection, the MIL will light up from engine starting) If a misfire is detected that will cause three way catalyst damage, the MIL will start blinking.)
2. Two Trip Detection Logic (Exhaust quality deterioration)
When a misfire that will not damage the three way catalyst (but will affect exhaust emission) occurs, the malfunction indicator lamp will light up based on two trip detection logic. In this condition, ECM monitors the misfire for every 1,000 revolutions of the engine.




DTC Confirmation Procedure

CAUTION: Always drive vehicle at a safe speed.

NOTE: If "DTC Confirmation Procedure" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 seconds before conducting the next test.

With CONSULT
1. Turn ignition switch "ON", and select "DATA MONITOR" mode with CONSULT.
2. Start engine and warm it up to normal operating temperature.
3. Turn ignition switch "OFF" and wait at least 5 seconds.
4. Start engine again and drive at 1,500 to 3,000 rpm for at least 3 minutes.
Hold the accelerator pedal as steady as possible.

NOTE: Refer to the freeze frame data for the test driving conditions.

5. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

With GST
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch "OFF" and wait at least 5 seconds.
3. Start engine again and drive at 1,500 to 3,000 rpm for at least 3 minutes.
Hold the accelerator pedal as steady as possible.

NOTE: Refer to the freeze frame data for the test driving conditions.

4. Select "MODE 7" with GST.
5. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

Without Scan Tool
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch "OFF" and wait at least 5 seconds.
3. Start engine again and drive at 1,500 to 3,000 rpm for at least 3 minutes.
Hold the accelerator pedal as steady as possible.
4. Turn ignition switch "OFF", wait at least 5 seconds, and then turn "ON".
5. Perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.
6. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

Diagnostic Procedure

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Component Inspection




IGNITION WIRES
1. Inspect wires for cracks, damage, burned terminals and for improper fit.
2. Measure the resistance of wires to their distributor cap terminal. Move each wire while testing to check for intermittent breaks.

Resistance:

Cylinder No. Resistance K Ohms [at 25 °C (77 °F)]
1 Approximately 6.5
2 Approximately 10.0
3 Approximately 8.5
4 Approximately 12.5
5 Approximately 8.5
6 Approximately 11.0

If the resistance exceeds the above specification, inspect ignition wire to distributor cap connection. Clean connection or replace the ignition wire with a new one.