Management Of The Signals - Fiat 1998 Marea Service Manual

Marea- Marea Weekend
99 update
SYSTEM MANAGEMENT STRATEGIES

MANAGEMENT OF THE SIGNALS

During starting, the control unit recognizes the phasing of the injection and the ignition which are vital for
the subsequent operation of all strategies.
This recognition is based on interpreting the succession of signals coming from the flywheel sensor, on
the crankshaft and the engine timing sensor, on the camshaft.
NOTE The term "square signals" refers to the collection of signals coming from the sensor on the crank-
shaft and those from the sensor on the camshaft which, due to the precise reciprocal position,
provide the control unti with a synchronized sequence of signals which the control unit is capable
of recognizing.
These signals are composed as follows:
- flywheel on the crankshaft: it has two symmetriacl sets of teeth, arranged respectively at 10°, 65° and
97° in advance of each TDC;
- wheel on the camshaft: it has two long inspection windows and a short one, whose size and position
allow the signal to be supplied as illustrated.
97°65° 10°
J U L J l
130°
1. cylinder TDC
2. Crankshaft angles
3. Crankshaft flywheel signal (engine rpm sensor)
4. Camshaft wheel signal (engine timing sensor)
NOTE The numbers relating to the signals indicate the crankshaft angles in advance of the next TDC.
Copyright Fiat Auto
ft
16v
180°
97° 65° 10'
J U L J l
120°
130°
I T
140°
360°
97° 65° 10°
97° 65° 10'
JU1_IU-
J U L J l
120°
J ~ L
140°
Engine
Fuel system
10.
540 a
5