Have found this info but does not give the values for the rear sensor.
Anyone know what they should be?
PETROL INJECTION
Richness regulation
17B
17B-4
HEATING THE SENSOR
The oxygen sensor is reheated by the injection computer when the engine is started.
Heating the oxygen sensor is stopped:
– when the vehicle speed is greater than
108 mph (180 km/h) (value given for information purposes),
– according to the load and engine speed.
UPSTREAM SENSOR VOLTAGE
The value read on the diagnostic equipment (except XR25) under the Upstream sensor voltage parameter
represents the voltage supplied to the computer by the oxygen sensor located upstream from the catalytic converter.
It is expressed in millivolts.
The voltage should fluctuate between two values during richness regulation:
–
150 ｱ 100 mV for a lean mixture,
– 750 ｱ 100 mV for a rich mixture.
The smaller the difference between the minimum and maximum values, the poorer the signal from the sensor (the
difference is usually at least 500 mV).
MIXTURE CORRECTION
The value read on the diagnostic equipment under the Mixture correction parameter represents the average of the
richness corrections made by the computer in line with the richness of the fuel mixture seen by the oxygen sensor
located upstream of the catalytic converter.
The correction value has a mid-point of
128 and limits of 0 and 255:
– value less than 128 = request for mixture to be made leaner.
– value greater than 128 = request for mixture to be made richer.
Note:
If the difference is small, check the sensor heater.
PETROL INJECTION
Richness regulation
17B
17B-5
ENTRY INTO RICHNESS REGULATION MODE
Richness regulation will start after a timed starting period according to the coolant temperature if the oxygen sensor
is ready (sufficiently warm).
In all cases, richness regulation should be active after
2 minutes if the coolant temperature is above 70 ｰC.
When the mixture regulation is complete the parameter value is 128. Refer to the richness regulation state on the
diagnostic equipment.
Unlooping phase
In the mixture regulation phase, the stages of operation during which the computer does not take into account the
value of the voltage supplied by the upstream sensor are:
– at full load,
– under heavy acceleration,
– under deceleration with a no load signal,
– when the oxygen sensor is faulty.
In this case the value
128 is displayed.
DEFECT MODE IN THE EVENT OF AN OXYGEN SENSOR FAULT
When the voltage from the oxygen sensor is incorrect (varying only slightly or not at all) during mixture regulation,
the computer will only enter defect mode if the fault has been recognised as present for
10 seconds. In this case
only the fault will be memorised, the parameter: "Mixture correction" is 128.
If an oxygen sensor fault is present and recognised and if the fault has already been stored, the system enters the
open loop mode directly.
