Wideband placement.

[SRT8Tech]

How big of a differance does it make to put the wideband O2 behind the Cats?? Ive heard that it should not be done and that it makes the readings wayyy off. True or not? Theres just not much room to put an O2 before the cats in an LX SRT8.

[Quick]

well... first off there's plenty of room in front of the cat. It's got to go on the driver's side, sort of adjacent to the narrowband and about the 2 o'clock position. The only difficulty is getting the cat off to do the job without dropping the entire exhaust. The studs off the header are pretty long so the cat has to move back a good ways to get it off the studs. You probably aren't going to have that kind of play in the joints and flexible hangers. If you get someone who knows what they're doing they'll just saw the cat in two (the pipe part, not the cat itself). Loosen the joint clamp and then you can pull it to one side and get the flange off the studs. Cut the hole, weld in the bung, get it back on the studs and weld the pipe back together. You really want to take it off because you don't want any metal scraps or filings from cutting the hole to get into the cat itself.

Ok. So the cats will mainly damp the fluctuations -- you won't see changes in a/f as quickly as you would in front of the cats. As for accuracy, it will probably be less than 0.2 from a reading in front of the cats. After all, they use a tail pipe sensor on dynos. But really, if you're going to the expense of buying a wideband and display why install it in a less than optimal location?

[sohfast94]

I've found the difference to be minimal on most applications that I've tested on the dyno. Normally 1-2% As long as the cat is lit off then you shouldn't have very much to worry about being that Mopar is normally relatively performance minded and has a decent flowing catalyst system.

[STR8_From_Hell]

I've found the difference to be minimal on most applications that I've tested on the dyno. Normally 1-2% As long as the cat is lit off then you shouldn't have very much to worry about being that Mopar is normally relatively performance minded and has a decent flowing catalyst system.

Excellent news. I have an 06 SRT8 that I installed long tubes on and now have no room to install a bung pre-cat unless I go into the header collector. That's all fine and dandy but welding in a bung will screw up the ceramic coating and that is something I am trying to stay away from. It will be much simpler to have a bung welded into the mid pipe post cat.....