Rough Idle

• Check switch condition signal circuit. See CODE 51 in appropriate article;

For GS300 TESTS W/CODES

For SC300 TESTS W/CODES

For SC400 TESTS W/CODES

• Check Idle Air Control (IAC) valve circuit.
• Check Volume Airflow (VAF) sensor circuit. See CODE 31 in appropriate article;

For GS300 TESTS W/CODES

For SC300 TESTS W/CODES

For SC400 TESTS W/CODES

• Check fuel injector circuit.
• Check EGR system.
• Check ignition signal circuit. See SPARK TEST under IGNITION CHECKS in appropriate articles;

For GS300 BASIC TESTING

For SC300 BASIC TESTING

For SC400 BASIC TESTING

• Check engine compression.
• Check fuel pump control circuit. See CODE 78 in appropriate articles;

For GS300 TESTS W/CODES

For SC300 TESTS W/CODES

For SC400 TESTS W/CODES

• Check ignition coil resistance.
• Check distributor sensors.
• Check spark plugs.