F 250 2WD Pickup V8-351 5.8L (1982)
Crankshaft Position Sensor: Description and Operation
Fig.6 - Crankshaft Position Sensor
Fig.7 - Crankshaft Position Sensor
DESCRIPTION
The crankshaft vibration damper is fitted with a four-lobe "pulse ring" which provides the system with an accurate indication of when the pistons
reach 10 BTDC. This indication is called the reference timing. Figs. 6 and 7.
The pulse ring is a powdered metal ring positioned on the crankshaft vibration damper during manufacture. It has four equally spaced lobes which
represent crankshaft position when the pistons reach 10 BTDC.
During operation, the lobes on the pulse ring pass by the tip of the CP sensor. The pulse ring interrupts the magnetic field at the tip of the sensor.
When the field is interrupted, an output signal is generated and sent to the ECA.
As the crankshaft turns, the ECA evaluates the electrical impulses to determine the exact position of the crankshaft at any given time. By the
frequency of the impulses, the ECA can determine the engine speed. With these two factors, the ECA will determine the appropriate ignition
timing advance required for best engine operation.
