Questionhello, I hope I can get some help from you.
I have a 2000 Land Rover discovery 2 , a computer diagnostic was telling me to replace the 4 O2 sensors, last week I had problems with one of them cause the four wire broke (my fault cause I was trying to clean them and I left wire hanging)and I had a lot of smoke on the exhaust , and a very strong smelling gas .So I replaced the four O 2 sensors yesterday , but the smell of gas and the smoke are still present in the exhaust system.
I am wondering if broking the wires for the rear sensor (actually I droved like that for 3 days ) could get any other aditional damage like the catalytic converter.thanks in advance
AnswerHi Marcelino,
it has been said that driving with faulty O2 sensors could result in catalyst breakdown - but it depends on fuel quality and how long it has operated under these conditions.
My guess would be that your system has to adjust itself to the new sensors OR the sensors were not installed properly.
Manual states:
"During adaptive fuelling conditions, information from the heated oxygen sensors (HO2 S) is used by the ECM to correct the fuel quantity to keep the air/ fuel ratio as close to the stoichiometric ideal as possible."
It sounds like your Disco is stuck in an OPEN LOOP FUELING position as a result of your initial O2 sensors failure and repair.
"Open loop fuelling does not rely on information from the HO2 S, but the air/ fuel ratio is set directly by the ECM, which uses information gained from the ECT, MAF/ IAT, the TP sensors and also the vehicle speed sensor (VSS). The ECM uses open loop fuelling under the following conditions:
1. Cold start.
2. Hot start.
3. Wide open throttle.
4. Acceleration.
The ECM uses open loop fuelling to control fuel quantity in all non adaptive strategy conditions. The ECM implements fuelling information carried in the form of specific mapped data contained within its memory.
Because there is no sensor information (e.g. HO2 S), provided back to the ECM, the process is called an 'open loop'.
The ECM will also go into open loop fuelling if a HO2 S fails."
So... its also possible that something else has gone wrong and that may explain why you are still in an OPEN LOOP FUELING stage.
Here's the possibilities:
Failure of the closed loop control of the exhaust emission system may be attributable to one of the failure modes indicated below:
1. Mechanical fitting & integrity of the sensor.
2. Sensor open circuit / disconnected.
3. Short circuit to vehicle supply or ground.
4. Lambda ratio outside operating band.
5. Crossed sensors.
6. Contamination from leaded fuel or other sources.
7. Change in sensor characteristic.
8. Harness damage.
9. Air leak into exhaust system (cracked pipe / weld or loose fixings).
System failure will be indicated by the following symptoms:
1. MIL light on (NAS and EU-3 only).
2. Default to open-loop fuelling for the defective cylinder bank.
3. If sensors are crossed, engine will run normally after initial start and then become progressively unstable with one bank going to its maximum rich clamp and the other bank going to its maximum lean clamp – the system will then revert to open-loop fuelling.
4. High CO reading
5. Strong smell of H2 S (rotten eggs)
6. Excessive emissions
Double check the wiring of your sensors and make sure the harness is ok. I hope this helps.
JohnMc
