Circuit Description
WARNING: This page is about a different car, the 1995 Lexus LS 400. However, it is still accessible from the selected car via links, so may be relevant.
A misfire is determined by the ECM. The ECM uses signals provided by the crankshaft and camshaft position sensors. If the engine speed rate has changed enough to equal a preset number, a misfire is detected and the MIL is illuminated. If the misfire rate is high enough, and driving conditions will cause catalytic converter damage or overheating, the MIL blinks when a misfire is occurring.
Code is set when misfiring of random cylinders is detected during any particular 200 or 1000 revolutions. Possible causes are:
- Ignition system.
- Injector(s).
- Fuel pressure.
- EGR system.
- Engine compression.
- Valve clearance.
- Valve timing.
- Mass Airflow (MAF) sensor.
- Engine Coolant Temperature (ECT) sensor.