O2 Sensor Reading Delay (Open-Loop) - A.E.B. AEB215 Manuel D'utilisation

VEHICLE CONFIGURATION
O2 SENSOR READING DELAY (OPEN-LOOP) (Fig. 27)
• Normally, the Oxygen Sensor behaves as follows:
- when the Oxygen Sensor is cold, that is, right after the engine has
been started, the voltage on the Oxygen Sensor signal carrier wire is
steady at about 0,45 V;
- after a few minutes, the Oxygen Sensor reaches the operating
temperature and the voltage on the signal carrier wire begins to
toggle between 0,2 V (LEAN mixture) and 0,8 V (RICH mixture);
- under these conditions, the LEONARDO works correctly.
• On some of the new vehicles, the Oxygen Sensor behaves
differently:
- when the Oxygen Sensor is cold, that is, as soon as the engine has
been started, the voltage on the signal carrier wire is kept at a steady
0,8 V (RICH carburetion signal) by the E.C.U.;
- after a few minutes, when the Oxygen Sensor has reached
operating temperature, the E.C.U. "unlocks" the oxygen sensor and a
voltage toggling between 0,2 V (LEAN mixture) and 0,8 V (RICH
mixture) can be read.
Under these conditions, the LEONARDO E.C.U. does not work
properly, because it reads a voltage of 0,8 V (RICH carburetion signal)
for several minutes during the cold phase. Under this condition, the
LEONARDO commands the fuel flow modulating stepper motor to close
the flow of the fuel completely; therefore, the engine stops
operating.
To eliminate this potential problem, it is sufficient to program the
unit to delay the reading of the Oxygen Sensor ("O2 SENSOR
READING DELAY").
To correctly enter the correct value of the delay, proceed as follows:
- select "DISPLAY PARAMETERS" (Fig. 28);
- start the engine on PETROL. Observe that on the tester display the
LAMBDA voltage is steady at 0,8 V;
- count the time elapsed between engine start and the point at which
the voltage begins to toggle between 0,8 V and 0,2 V. This is the
value that is to be entered in the "O2 SENSOR READING DELAY"
(Fig. 29). We recommend adding a few seconds to this value.
With this programming, the LEONARDO ignores the Oxygen Sensor
signal for the time progammed, and keeps the stepper motor at its
DEFAULT value. The LEONARDO becomes operational after the
oxygen sensor has been "unlocked" by the E.C.U..
Is215-2 Rev. 110105-2
LEONARDO
O2 SENSOR READING
DELAY
5 s
Fig. 27
ACT 95 DEF 100
RPM 900 RPM
TPS 0.80 V ™ ™ ™ ™ ™ ššš
ššš ššš
ššš ššš
LBD 0.80 V šš
šš šš ™ ™ ™ ™ ™
šš šš
Fig. 28
O2 SENSOR READING
DELAY
30 s
Fig. 29
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