Daytona V6-181 2972cc 3.0L SOHC VIN 3 FI (1992)
Pick-Up Coil: Description and Operation
Optical Distributor
Location
Housed in distributor.
Purpose
The PCM uses this input to determine engine speed and crankshaft position, and adjusts ignition timing, fuel injection, and idle speed accordingly.
Operation
Pick-up generates pulses when slots pass between Light Emitting Diodes (LED's) and photo diodes.
Theory
A thin disk, with 2 sets of slots, spins at half engine speed, between two LED and photo diode pairs (optical sensors).
The outer or "high data rate", slots pass through the corresponding optical sensor 1 slot per 2 degrees of crankshaft rotation.
The inner, or "low data rate", set of 6 slots, correspond to top-dead-center for each piston.
During cranking and at idle, engine speed changes with the firing pulse of each cylinder. Therefore the "high data rate" signal is used to time
ignition correctly for engine speeds up to 1200 RPM.
Above 1200 rpm, speed changes due to individual firing pulses are negligible. Therefore the "Low data rate" slots are used to time fuel injection
and ignition at engine speeds above 1200 RPM.
Note: If the PCM does not detect input from the pick-up, the PCM de-activates the ASD and fuel pump relays, interrupting power to the fuel pump,
injectors, coil, and oxygen sensor heater, preventing fuel injection and ignition, (a no start condition).