I will install a downpipe and a catback, I already have a cat-delete. Actually my UEGO O2 sensor is installed on the stock downpipe and the stock O2 sensor is on the cat-delete. Here is my question. Could I install the UEGO O2 sensor after the cat-delete or should be on the downpipe? I asking because the catback already have an O2 sensor bung.

 

Yes, you can. However, you'll see a little more lag in the readings due to the increased distance from the motor. It shouldn't really be noticeable though.

 

Thanks! Actually I did the installation yesterday and it is reading perfect. Here is a couple of pics.

 

as close to the exhaust manifold as possible

 

no thats wrong - it should be as far from the turbo as possible but before the cat...

 

I know, it is too hot for the sensor....

 

not only that but the turbo causes turbulance which is reduced the futher you go back in the exhaust

 

Please leave your installs to a trained professional. And keep your assumptions to yourself. Listen to the other poster. About 36" away from turbo, but before the cat. You could put yours in the cat if its a HFC and has an extra bung. But I wouldnt put it past the cat, HFC or not.

 

You don't want the sensor between the manifold and the turbo. According to Corky Bell (he wrote the book on turbochargers called "Maximum Boost") the pressures there are too high for it to function properly. I agree with the others that it belongs between the turbo and cat. One thing to look out for is that the sensor does not sit at a low point.

If the sensor sits at a low point where condensate or other moisture can collect it may crack due to thermal shock when the heater to the sensor turns on suddenly. Normally you would want to mount it @ 3, 9, or 12 o' clock.

 

I agree as well between the turbo and the cat... anything after the cat will be distorted since it will convert the elements around (hc, co, nox)

 

on the HKS exhaust, it comes w/ a bung for a wide band O2. I plugged it w/ the bolt since i dont have one. But its on the main pipe before the muffler. Definately after the Cat/Test pipe which housed my #2 O2. So this is too far back for a wide band?

 

yes your WB should be before the cat

 

When i bought my WB from PLX they said mount it at least 24" away from the turbo, because of the amount of heat generated by the turbo, and before the cat. So that basically works out to be at the back of the DP and make sure it is between the 9 o'clock and 3o'clock positions.