Oxygen sensors. What do they do?

[Ladaman]

The reason I ask is, on the M15A engine from the Ignis sport I'm fitting in the Sammi, the exhaust manifold/down pipe has an oxygen sensor just before and just after the cat'.

The Jimny manifold I'm using has one just before the cat'. I believe there is one halfway down the exhaust also, but I have only seen a diagram of that.

So can I bin the second one, or even both?

I'm not sure if the second one has any effect, as before my son pranged the Ignis, he had de-catted the manifold, so the readings would have been wrong but it seemed to run okay.

[turbo-tom]

oxygen lambda Sensor does is send signals to the ecu so that the engine can run a leaner mixture once the car has warmed up also the one after the cat just monitors if they cat is working etc

http://ngkntk.co.uk/index.php/technical ... sensor-do/

[dan_2k_uk]

Sense oxygen??? ........sorry

[Jordi]

I know i said my Zuk had electrics in another post but thats far too technical.

[Ladaman]

oxygen lambda Sensor does is send signals to the ecu so that the engine can run a leaner mixture once the car has warmed up also the one after the cat just monitors if they cat is working etc

http://ngkntk.co.uk/index.php/technical ... sensor-do/

So the first one is quite important and needed. I'd best fit that one. Still not sure about the second one.

Sense oxygen??? ........sorry

I did leave the door open I suppose.

[turbo-tom]

yeah fit the first one id say it it monitors air to fuel etc and adjust as i take it you running injection still?

so run the first on pre/before the cat if you running one?and another afterwards as the second one after the cat monitors how well the cat is doing but if you not running a cat just run the first one but id leave the wiring there for the second one if you ever need it!

hope it makes sense what im splilling on about

[Ladaman]

yeah fit the first one id say it it monitors air to fuel etc and adjust as i take it you running injection still?

so run the first on pre/before the cat if you running one?and another afterwards as the second one after the cat monitors how well the cat is doing but if you not running a cat just run the first one but id leave the wiring there for the second one if you ever need it!

hope it makes sense what im splilling on about

I think I know what you're saying.

Yep def keeping the injection. So I will fit the first, pre cat one, and probably leave the cat in the manifold at least for the time being, then again it's not hard to break it out, and get a bit more power I certainly don't need it for the MOT.

I've got the second sensor, but I think it will be staying in the garage now. Wiring to stay in place.

Checking this video out


Click Here for Youtube Video



I think this means, no sensor, so no voltage, so the engine management will think its lean, so worst case it will just use more fuel. It not my day car so who cares?

Does that sound right?

[turbo-tom]

Yep sounds good to me worst case if you need to run the second one after the cat just drill a hole weld in a nut and put the sensor in job done!

and yep Eric is top notch we use him alot at college!

[twiss]

The ECU compares the fuel mix readings it gets from both of the lambda sensors (before cat and after cat).
This way it can tell what effect the catshit converter is having on the exhaust gases

[Rhinoman]

During normal running the ECU will drive the mixture alternately rich and lean and measure the time taken for the sensor to respond, from that it deduces if the mixture requires adjusting. If the first sensor isn't fitted and the ECU does not see the reading change with the mixture then it will set a fault code and revert to base settings - how much effect that has depends on the condition of the engine. The second sensor is used to test the effectiveness of the cat, no sensor will flag a fault but you can connect the sensor and leave it in free air, that's usually enough to cheat it.