Curious guys i have my wideband placed behind my car sound metal core cats on my V6 project suv. How much off will the readings be ?

 

almost impossible to say. depends on how efficient your cats are. readings after cats are useless.

 

I looked into this a while ago, and the conclusion I came to is that the readings are not useless, but that they will be more accurate the farther you are away from stoich, and the more volume of exhaust is being forced through the cats. It seems that at WOT on a fairly high HP car (especially a turbo car that is running fairly rich for in-cylinder cooling effect), the readings after the cats may be fairly accurate.

 

Only thing this is a v6 with maybe 200 whp lol. with long tube headers.

Im guessing id be better off just welding a bung to say the left bank pre cat and take my readings from there vs from behind the cats at the Y pipe

 

your readings will be way off......if you ever look at a post cat o2, it hovers at half a volt....basically stoich.

if you put the wideband after the cat, if you are running rich, your cat will burn up what the engine doesnt. thus giving you a false reading.

you need to go pre cat with the wideband.

if this is wrong, i apologize, this is how it was explained to me.

 

Here's a prior thread that has some useful links in it:

https://honda-tech.com/forums/forced-induction-16/wideband-sensor-after-catconverter-2538548/