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Fernandez · 08-15-2007, 09:44 AM

Hi Therealroy!

The Oxigen sensor (also called Lambda sensor) lives in the exhaust system, very close to the catalytic converter and therefore very close to the exhaust manifold. This device measures the amount of oxigen in the exhaust gases. By doing this the ECU knows how the air/fuel ratio is and can adjust it accordingly. The ideal ratio is, if I remember correctly, 14.7/1 (in terms of mass, not volume). This seems to be the ideal for both combustion and catalyst efficiency and survival. The ECU then adjusts how much fuel is injected in the intake manifold by modifying the amount of time the injectors are opened.

Cars with On Board Diagnostic systems can store fault codes relating to the oxigen sensor. That is what happened in my case.

Changing the Oxigen sensor is pretty simple (although you need ramps to elevate the front of the car). Cost in my case (M104 engine) was around £100 (?around 200 US dollars) for a genuine MB part.

Don't forget to check the other possible culprits, as mentioned somewhere else in this post and tell us what finally resolves the problem.

08-15-2007, 09:44 AM	#15 (permalink)
Fernandez BenzWorld Junior Member Date registered: Mar 2007 Vehicle: Mercedes-Benz 280TE 1993 Location: Lanarkshire-Scotland-UK Posts: 42	re: idle surge Hi Therealroy! The Oxigen sensor (also called Lambda sensor) lives in the exhaust system, very close to the catalytic converter and therefore very close to the exhaust manifold. This device measures the amount of oxigen in the exhaust gases. By doing this the ECU knows how the air/fuel ratio is and can adjust it accordingly. The ideal ratio is, if I remember correctly, 14.7/1 (in terms of mass, not volume). This seems to be the ideal for both combustion and catalyst efficiency and survival. The ECU then adjusts how much fuel is injected in the intake manifold by modifying the amount of time the injectors are opened. Cars with On Board Diagnostic systems can store fault codes relating to the oxigen sensor. That is what happened in my case. Changing the Oxigen sensor is pretty simple (although you need ramps to elevate the front of the car). Cost in my case (M104 engine) was around £100 (?around 200 US dollars) for a genuine MB part. Don't forget to check the other possible culprits, as mentioned somewhere else in this post and tell us what finally resolves the problem.