Hello

I want to put a stainless steel de-cat exhaust on my car from the turbo back. There is a hole in the the stainless exhaust for the lamba sensor but 'my mate' reckons that the lamba wont work beacuse there is no cat.

is this right?

Thanks
Steve

 

If the lambda isn't fitted the ECU won't be able to monitor the fuelling so it will throw a fault code. The fuelling will be way out and it won't run well without being remapped for a decat.

 

Think that's bill-hooks. Lamda sensor measures how much oxygen there is in the exhaust - this is really important to the ECU, and the health of your engine, regardless of whether there's a cat or not.

I think "your mate" is referring to the sensor that determines the temperature of the catalytic converter itself. That, obviously, won't work without a cat, so you have to either have the error mapped out, or replace the sensor with a resistor that fools the ECU into thinking the cat temp is OK.

Or, I might be talking bill hooks

 

Thanks for the help guys

'my mate' definatley meant the lamba, just so i'm talking about the right item the sensor I am referring to is on the downpipe behind the turbo

I wouldn't normally question what he tells me, it's just I was puzzled why the would make a hole for the lamba in the exhaust if it wasn't needed.

I will have to fit the lamba after hes gone....he doesn't like being wrong

 

My decat downpipe definitely has a sensor in it

 

no chance of dumping the 02 sensor then?

 

Even with a decat, you'll need it to manage the air/fuel ratio

 

What MY is the car???

If its an early one then the O2/Lambda sensor is in the drivers side manifold, easily spotted by sliding under the f/o/s and taking a look, and if so then the sensor you are talking about is the exhaust gas temp sensor or 'cat on fire'.

If this is the case and you have a de-cat then the sensor is obsolete

 

You must run the lambda sensor as it sends a signal to the ECU which attempts to run the engine at stoich when in closed loop. ie tickover and while in vacum, not boost.
You are in vacum for a large proportion of the time as you will see if you have a boost guage and importantly while in the cruise.
By running lambda your car will operate smoothly and use less fuel than it would do without the lanbda.
If you have reported accurately what your mate has said then he clearly has large gaps in his knowledge and maybe you should question what he says more often because this piece of advice from him is totally duff.