Lambda Sensor

[big_ralge]

Hi all has anyone any pics of where the lambda sensor is and how to remove it.

 

Thnx John

[Ivor_E_Tower]

Why? Have you bought some fuel at a Tesco or Morrisons? ^_^

[HullHornet#30]

what is the sensor and what does it do.

[big_ralge]

Why? Have you bought some fuel at a Tesco or Morrisons? :lol:

LOL no i haven't emissions are a little poor.

[whitty]

lambda sensor is basically an oxegen sensor it allows the ecu to see and constantly adjust the fuel mixture using a closed loop system

 

you should find your lambda sensor bolted into the exhaust front pipe or manifold and you will find one on pretty much every car built since about 1992

 

 

if yours is playing up it usually goes 1 of 2 ways either leans fuel mixture right off causing v poor performance and stalling ect or the other way yes you guessed it very rich fueling black exhaust smoke, poor performance ect ect

 

 

don't panic though! !!

 

lambda sensors are not expensive ! although they can be if you walk into your local main dealer!

 

go to good motor factor and ask for one they will probally ask you how many wires 1,2,3 or 4

 

1 wire sensors just feed the ecu

2 wire sensors usually feed ecu and go to earhth on vehicle or to ecu and to earth

3 wire sensors 1 wire feeds the ecu the other 2 are a heater inside the sensor basically lambda sensors dont work properly till they are hot so bosch ect in their wisdom fitted a heater so they worked better

4 wire sensors are as 2 wire ones but have the heater also

 

when you get your new sensor from factors

all you do is remove old sensor (usually a 22mm spanner) from your front pipe and unplug the sensor from the car

cut the wires off the old sensor and following instructions you got with new sensor and using the supplyed crimp style connectors join the new sensor to the old wires

put sensor back in exhaust

plug it back in

 

job done!!

 

simple 40mins job nothing hard and not expensive last one i brought was a 3 wire and it cost me

[Scorpiorefugee]

Hi Whitty,

 

Mine are all diesels so I'm not over worried about lambda sensors and rough petrol but I must complement you on a brilliantly useful post.

 

Thanks and a belated welcome to the 'club'

 

Ron.

[big_ralge]

Is the lambda sensor a 4pin connector on the 2.0 galaxy?

 

Thanks

 

Big_Ralge

[Smilge]

Its all based on the principle of a galvanic oxygen concentration cell with solid-state electrolyte ...... anyone interested? I could talk all day about it. :ph34r:

[NikpV]

actually I am how do they make it reversible - what electron donor reaction do they use ??

[mumof4]

oh Gawd nik....please no!!!!!!!!!!!!..

[Smilge]

actually I am how do they make it reversible - what electron donor reaction do they use ??

 

Now your asking Nik ........ to do with the number of excess electrons and electron holes within the solid state electrolyte .... thats all I know and as far as reversing it is concerned...where does that come into it? :ph34r:

[NikpV]

if it were a non-reversible process then once the electrolyte had been used up you would need to replace the sensor. I presume that a higher concentration of oxygen would allow electrons to migrate thriugh the material ???

[Smilge]

Nik, when the sensor is subjected to 350 degrees C, it allows oxygen ions to flow through a zirconium dioxide lattice. There are two platinum electrodes which measure a reference gas (air) and the exhaust gas and with the flow of oxygen ions across the Zirconium oxide will produce a voltage between the two electrodes. The size of this voltage is based on the oxygen partial pressure differential created by the reference and exhaust gases. So basically, if the engine is running rich the sensor will produce 800 to 1000mV (λ<1) but is only about 100mV with weak mixtures (λ>1) but the transition from the lean to the rich range lies at 450 to 500mV. So yes, although the sensor contains a porous ceramic layer on the exhaust gas side of the sensor to prevent contamination, the porosity of the ceramic layer will be affected eventually by contaminants within the fuel.

[NikpV]

thanks for that, how long will it take for the sensor to reach its 350ºC I assume that the sensor contains a heater rather than depending on exhaust gas temp due to the variations in the pO₂ that this would entail. I wonder if the porosity being affect

ed by the contaminants is the problem currently being experienced.

 

Would disconnecting the sensor allow the ECU to use a failsafe value or do you think that nowadays the engines are running so close to the limits that it would still give a rough running engine?

[Smilge]

Would disconnecting the sensor allow the ECU to use a failsafe value or do you think that nowadays the engines are running so close to the limits that it would still give a rough running engine?

 

Dont really know Nik, I would say that the Lambda sensor will operate in open loop control in failsafe mode and in closed loop control to operate within 1% of the stoichiometric ratio (λ=1) once it has got up operating temperature (around 20 to 30 seconds with a heated sensor @ 600 degrees C). Just out of interest, closed loop control is only applied when it is at 350 and the response time is then <50mS. Complicated stuff!