Repair Manual

17
IGNITION AND INJECTION
17 - 21
For starting the oxygen sensor as soon as possible after the engine start up it should be
heated by its electric resistance, type PTC = positive temperature coefficient.
The evacuation track of the burned gases should be 100% sealed in the area in front of
the ë rod and of the catalytic converter in order to not get measurements errors of the
oxygen content in the burned gases.
Reference values:
- heating resistance of the ë rod: R
1-2
= 1 – 15 Ù
-R insulation = R
1-4
= R
1-3
= R
2-3
= R
2-4
> 25 MÙ at 20 °C
IMPORTANT: Only fuel without lead should be supplied. Otherwise the oxygen sen-
sor and the catalyst will be broken. The oxygen sensor and the catalyst are damaged in
case of overheating caused by a difficult starting up or by an improper functioning of
the engine.
The correlation between the value ë and the dosing of the mixture is indicated in the
diagram here under.
The voltage limit values are U ë = 0.9 V for a rich mixture and U ë = 0.1 V for a poor
mixture. The value U ë = 0.45 V, existing between these two, is the reference voltage
existing in the computer memory; the later uses it in case of damage of the ë rod, the
engine being under running.
The value ë
1
= 1 ± 002 is the area of the voltage jump characteristic to the ceramic
element (ZrO
2
in this case).
A voltmeter with internal resistance R
i
= 10 MÙ is used for measuring the voltage generated
by the ë rod. This voltmeter will be connected to the ë rod (pins 3 and 4) or to the elec-
tronic control unit (pins 9 and 10).
Mixture
rich
Mixture
poor
DESCRIPTION OF THE SYSTEM
vnx.su