If the igniter is bad, the ECU won't receive the "feedback" signal and will stop firing the injectors after a few seconds. Rough Idle or Stalling
Ensure 12V is present when the key is in the "On" position.
A "dead spot" in the throttle position sensor signal will cause hesitations during acceleration. Safety and Best Practices toyota 4afe ecu pinout
Power Grounds for injectors and heavy-load components. 2. Ignition and Timing Crucial for starting and maintaining a smooth idle.
Never use a test light on ECU pins, as the current draw can fry the internal circuitry. If the igniter is bad, the ECU won't
The signal from the MAP sensor. THA: Intake Air Temperature sensor signal. THW: Coolant Temperature sensor signal.
The 4A-FE uses a Speed-Density system (using a MAP sensor) or a Mass Air Flow system depending on the region and production year. Most ECUs utilize three main grey or yellow plastic connectors. Common Connector Layouts Primary engine sensors and power. Safety and Best Practices Power Grounds for injectors
When testing a running engine, slide your probe into the back of the connector rather than piercing the wire insulation.