What signals injector to pulse on a 1985 corvette?

In a 1985 Corvette (likely with a TBI system - Throttle Body Injection), the signal to pulse the injectors comes from the Engine Control Module (ECM). The ECM receives various inputs from sensors throughout the engine, such as:

* Throttle Position Sensor (TPS): Indicates how much the throttle is open. More throttle generally means more fuel is needed.

* Manifold Absolute Pressure (MAP) sensor: Measures the pressure in the intake manifold. This helps determine engine load.

* Air Flow Meter (AFM) (if equipped, some 1985s may have different setups): Measures the volume of air entering the engine. Crucial for calculating fuel requirements.

* Crankshaft Position Sensor (CKP): Signals the ECM the crankshaft's rotational position, crucial for precisely timing the injector pulses.

* Coolant Temperature Sensor (CTS): Provides information about engine temperature, influencing fuel delivery.

The ECM uses these inputs, along with its internal programming, to calculate the required fuel pulse width for each injector. This pulse width is then sent as a signal to the injectors, causing them to open and inject fuel for a specific duration. The signal itself is usually a ground signal; the ECM grounds the injector circuit to activate it. A specific driver circuit within the ECM handles this.

In short, it's not a single signal, but a complex calculation within the ECM based on multiple sensor inputs that ultimately triggers the injector pulses.