Repair Manual

IGNITION AND INJECTION
17
17 - 8
Fig. 3
The valve potentiometer consists of a first potentiometer, working on the range
(0° - 22°) and a second one, working on the range (19° - 90°). A common area is noticed,
between (19° - 22°) established for a more precise reading of the load necessary in the
partial load area, the most used for the engine exploitation.
The connector of the valve potentiometer consists of the following connections (drawing 2):
1 - Mass ( pin 27 computer )
2 - Potentiometer I ( 0
0
- 22
0
)
3 - Blank
4 - Potentiometer II ( 19
0
- 90
0
).
5 - Supply ( 15 V, pin 25 computer ).
In can be checked by means of means of an oscilloscope as follows:
- engine on contact;
- manual moving of the control clutch lever;
-oscilloscope contacted to the pins 1 and 2 of the connector; if the displayed sign
looks like a row of horizontal straight lines with no interactions the potentiometer is ready
to use (drawing 10)
In case of damage, the potentiometer is not to be repaired – the lower part of the injection
central unit is to be replaced.
The wires of the potentiometer connector should be checked by an ohmmeter. The
following values are indicated for a good potentiometer:
- potentiometer I R
1-5
= 600 – 1400 Ù
- potentiometer II R
2-4
= 400 – 4000 Ù;the maximal values should
contact each other within the partial load area.
Fig.4
DESCRIPTION OF THE SYSTEM
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