DFelton

iTrader: (4)

When tuning a car on a dyno, tuners use the sniffer in the tailpipe, right? People tune cars with and without catalytic converters, right? Then why the hell does everyone make such a big deal out of putting the WB 02 before or after the cat? Has any ACTUAL testing been done to confirm there is a difference? From what I have heard, it's not even .1 afr difference. I wish I had logged before I went to a test pipe ( literally JUST started being able to log). However I don't see a difference looking at the guage.

Does anyone have conclusive evidence on this? I'm curious to see hard facts, and to the armchair mechanics, cool it. I'm not looking for speculation.

-Doug

Sharkbite2000

iTrader: (21)

I guess that's the sweet spot for the gases.

Babs

iTrader: (26)

For a catted car, it might make a difference. Most of the dyno runs you see are more than likely with a test pipe. And in that case, I don't think it makes much difference. Now the angle at which you install the bung relative to the horizon does make a difference but if it's test piped, then it doesn't matter really.

Most people, including me, put it right at the end of the downpipe for ease since there is a grommet you can push out and feed the sensor cable to the inside of the car.

DFelton

iTrader: (4)

I see what you saying, but my argument is that people seem to scream and shout whether the sensor is put before or after the cat. My point is, I don't think the cat has any effect on the reading.

chaotichoax

iTrader: (149)

I highly doubt that 98% of cars dyno'd are catless

that's just a silly observation

tuners don't solely rely on afr's when tuning...although I'm sure there is a suggested addition/subtraction afr method for a catted car when using a tailpipe sniffer

SmurfZilla

iTrader: (33)

The further downstream the Wideband the less accurate the reading is.

EVO8STI

iTrader: (2)

idk mine is right before the cat and its just fine for me and thats how it will
stay