i know the ideal position would be to put one before the cats.
On the SC400 it is a little tiny bit difficult.

Is it okay to put it aftercat?

I ask because when i went get my car dyno-tuned they put the O2 sniffer on the tailpipe to get the A/F readout....

anyone?

thank you

dennis

 

^^^

 

please~~

 

on the turbo cars, they are installed before any cats, i suggest doing the same.

 

the thing is when you go get the car dyno tuned, they put the sniffer on the tailpipe.... if i am not using the wideband for real-time and if i am using it to datalog-then-tune it shouldn't make a difference right?

 

isnt the cat, burning the unburnt fuel? so your reading may not be accurate.

thats my guess.

 

that's what i was thinking exactly, but when i was at the dyno last time getting my car tuned they said it didn't really matter. I mean they are supposedly pros so they should know, but i just couldn't come to accept that.

I checked with supraforums and i had mixed answers. Some say close to factory o2 some say doesn't matter if it's in front of the muffler...

What bugs me though is that just about every dyno-tuning facility will use the tailpipe sniffer to tune your car... which leads me to believe that it is okay to have it after the cat.....

what do you think?

 

dont trust these pros, all they want is your money!

its hard for them to weld in a bung, so they stick in the mufller.

 

man this just makes things harder... This means i'm going to either drop the headders and add a bung and re-install

or

take the stock cats out, build a pipe and relocate the cat further downstream so i can went the bung in pre-cat....

it just doesn't get any easier.....

 

I don't know about the "pros" that use a sensor in the tailpipe My guy replaces one of the stock O2 sensors with a wideband when he tunes!
At any rate, DON't put the wideband sensor behind the cat, you may as well not even use it since the readings will be pretty much useless. Think about it, the cat is cleaning up what the wideband is supposed to be sensing!
The ideal position is 12-18" down from the exhaust port. Any closer and it could burn, any further and it takes too long to warm up (from the AEM literature).