wideband location

[oleshifty]

I am finally ordering my nelson tune. My county has emissions, but the truck isn't um.... driven on the street. I want to have the rear 02s turned off so it won't throw any codes just incase I ever have to get it tested.


I am also getting a wideband gauge/sensor. Can I put this in the 'after the cat' location on the stock piping until I get my headers on, or will the cats throw off the wideband reading?

[badseed91]

Your going to want the wideband pre catylist. The converter will change what it reads and make it where you cant effectively tune it. Plus the converter is another variable that is constanly changing in different conditions. OEM's use the forward 02's for fuel control for those reasons. Im not sure what a wideband will read mounted after the catylist but it will most definately read something completely different from what the actual a/f is either lean or rich. I want to say it will read rich but i cant remember this morning for some reason. If you mounted the wideband after the cat and you had tuned it off of that somehow and say your cat went bad (lost efficiency P0420, p0430) the wideband would read completely different and throw off your whole tune. Put it in front and you will be ok.

[oleshifty]

I'll just wait til the headers go on then

[blackjack325]

what about me, who doesnt have cats?
I have long tubes with an off-road y-pipe, where can i put the a/f ratio 02 sensor?
After the Y meets on the passenger side?

[oleshifty]

i'll be putting mine after the Y once headers go on. That way it sees an average from the 2 banks. I'm going with the stainless ebay headers, so technically I could put them on 1 bank or 1 on each bank...but that seems a bit extreme for 'monitoring'

[jetmech]

i'll be putting mine after the Y once headers go on. That way it sees an average from the 2 banks. I'm going with the stainless ebay headers, so technically I could put them on 1 bank or 1 on each bank...but that seems a bit extreme for 'monitoring'

That's what I do. I have my wideband's 02 sensor after the merge on the Y-pipe and I still have my factory CATs. I won't say the CAT's won't give a not-so-good reading for the wideband but this setup has worked GREAT for me. BTW, when we tuned my truck, we had the Dyno's wideband clipped into the tailpipe and that worked well too. 30k boosted miles later everything is still working just fine

[badseed91]

How on earth do you tune with a wideband after the cat? I gotta know.

[jetmech]

How on earth do you tune with a wideband after the cat? I gotta know.

You just tune it like you would if the wideband was pre-cat. Is it REALLY that amazing that I have my truck tuned with the wideband post-cat? It works VERY well and I've never had a problem with my tune.