Camaro RS V8-305 5.0L VIN E TBI (1990)
Electronic Spark Timing: Description and Operation
High Energy Ignition (HEI) System - PFI
The Electronic Spark Control (ESC) system module sends a voltage signal (8 to 10 volts) to the ECM when no spark knocking is detected by the ESC
knock sensor, and the ECM provides normal spark advance. When the knock sensor detects spark knock, the module turns "OFF" the circuit to the ECM
(0 volts). The ECM then retards EST to reduce spark knock.