Oxygen Sensor Bush

[cb750]

Got to take the silencer and pipe off my 3A so was thinking of having a bush welded on it to take an oxygen sensor in the future. Are there any requirements as regards positioning? Is the diameter of the pipe ok at this point to avoid clearance issues (52mm diameter)? I was going to use an 18mm stainless bush and plug and mount it on the top of the silencer inlet pipe.

[Guest 2b cruising]

I was under the impression they are meant to be before and after the cat.

[cb750]

Haven't got a cat fitted.

[Guest lotusPaul]

I have a 4-2-1 manifold. My wide band is fitted just by the 1 joint. Instructions say 600mm from head flange so it's about right. It should be before cat.

I have a full stainless exhaust and the boss is stainless too.

[cb750]

My exhaust is similar to yours, stainless, no cat, But with 4 into 1 manifold. I was going to have the bush welded on the silencer pipe very near the first system joint (manifold to silencer pipe joint) which puts it about 200mm from the 4 pipe joint and about 1 metre from the head joint. Do you think this will be ok?

[alanrichey]

The Superspec was fitted with a lambda sensor as standard (as well as a cat). The boss is about 70mm from the manifold/silencer pipe joint which puts it 400mm from the 4-1 joint.. Don't know how crucial the positioning is though, although it must be before the cat.

 

Although I agree the cat is irrelevant, as that is designed to clean up the gases, the lambda sensor feeding back to the ECU is to control the fuel/air mix.

Edited June 16, 2016 by alanrichey

[Guest lotusPaul]

The reason for it being as close as possible is for heating the element quickly, not so relevent with later designs, but also it allows quicker or more efficient use of the electronics when using wide band sensors.

[cb750]

Thanks for the advice. Just ordered the parts. At the moment I only want the access to possibly help tune the carbs (but fuel injection in the future?)

[Guest mcramsay]

The sensor needs to be before the cat, and to be in the section of pipe where the 4 branches come together into 1. That way you won't be reading the mixture of one cylinder alone. Also you have to have the boss welded at the 12 o'clock ( or close) position as the lambda sensors do not like any condensation that you can get pooling inside the pipes

[alanrichey]

Superspecs have them mounted at between 3 o'clock and 4 o'clock. Why am I not surprised

[Guest lotusPaul]

If anyone is after a wide band sensor I can reccomend Emerald. I have one they sell. Mine's obviously wired into my ECU to give full fuel control but it can work as a stand alone reader with a dial display.

 

Nothing but a very happy customer