Idle Mixture: LS400
- Ensure idle speed is within specification. Install jumper wire between VF1 or VF2 and E1 terminals of check engine connector. Connect positive (+) probe of voltmeter to terminal VF1 for left bank or VF2 for right bank and negative (-) probe to terminal E1. See Fig 1 and Fig 2.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
- Start engine and maintain engine RPM at 2500 RPM for approximately 120 seconds. With engine RPM at 2500, count the number of times voltmeter fluctuates between the specified voltage. See IDLE MIXTURE TEST SPECIFICATIONS table.
- If the number of fluctuations is less than minimum amount, check for air leaks at air induction system, defective airflow meter or throttle body.
- If fluctuations were within specification, accelerate and hold engine at 2500 RPM for approximately 2 minutes. Install exhaust gas analyzer probe in tailpipe at least 1.3 feet. Wait one minute and check idle mixture readings. If readings are not within specification, see IDLE MIXTURE TROUBLE SHOOTING table.
IDLE MIXTURE TEST SPECIFICATIONS
| Model |
Voltage |
Minimum Fluctuations |
| All Models |
0-5 |
8 Per 10 Seconds |
IDLE MIXTURE TROUBLE SHOOTING
| Problem |
CO/HC |
Probable Cause |
| Rough Idle |
Normal/High |
Incorrect Ignition Timing, Faulty Ignition Components, Incorrect Valve Clearance, Defective EGR Valve, Leaking Intake/Exhaust Valves, Defective Cylinder |
| Rough Idle |
Low/High |
Vacuum Leaks, Lean Mixture Causing Misfire |
| Rough Idle |
High/High |
Restricted Air Filter, Plugged PCV, Faulty Pressure Regulator, Clogged Fuel Return Line, Defective Coolant Temperature or Air Temperature Sensor, ECU, Fuel Injector, Cold Start Injector, TPS, Airflow Meter |