What's up people...


Quick question. How much of a difference in AFR reading would I get if I use a wideband in the 2nd O2 sensor port on a cat back exhaust?

I have a Greddy TiC with the second o2 port just where it bolts to the cat, but the JDM cars as the Evo 7 only carries one. So I'd like to connect the wideband there but been reading where it's not quite the best thing to do... but I'm not sure I want to add a bung on to the car just yet...

 

Closer then better. I prefer it on the downpipe.

 

You could use the second bung if you ran a test pipe. If the stock cat is on there, you have to weld a bung in the downpipe. BAsically, the cat will affect the AFR reading.

 

I see...

but then with the stock cat how much would it be "off" ?

Why I ask as well is because I know some people tune via attatching the sensor to the tailpipe...

 

Have a bung welded into the downpipe for more accurate readings.

 

most people that are getting tuned like that don't have a cat

you would have to ask a tuner for a better idea how "off" the reading actually be

 

Off enough to negate the advantage of installing a wideband in the first place. Don't waste money, do it right. Just have a bung installed in the downpipe.

 

Distance from the turbo only hurts response. During WOT the air is moving so fast that having it in the tailpipe is fine - even with a cat. Having it before the cat and closer to the turbo will help during normal driving and understanding more accurate AFRs.

 

I have mine in the that location in my TiC, no cat, and was told my Chris of Mellon Tuning it would be fine. I got tuned with it there and haven't had any problems.

 

1. you must put it before the cat or it will throw off the AFR alot....
2. you can put it as far as end of the muffler if you want but again, readings will be off slightly. alot of tuners just stick a sniffer right into the muffler on a dyno, havent you noticed?
3. the manufacterer will give you recommendation on the placement of the bung. it should be above the 3 or 9o'clock position(reduce chance of burning out from moisture and temp shock) and should be a certain inches away from the turbo or risk it burning out. middle of the DP to before the cat is probably optimal

 

if you ran it in the 2nd o2 bung....where are you gonna put your o2 sensor? you would have a CEL and the car would run like sh*t

 

wha??? only the 1st o2 matters for proper operations, o2 is only for emissions

 

all i know is when my cutout was opened, the car ran completely different and always had a CEL

 

no offense but your first statement is VERY incorrect, 2nd o2 is PURELY emissions only. i wont go into it too much but cutout issues is a different topic altogether

i havent been very interested in cutouts myself but i heard of various issues from it including exhaust leaks, cutout valve motor getting burned etc etc but nothing to do with your 2nd o2