Question about tuning and O2 sensors

[gunnin4ya]

About to do a OBDII to OBDI conversion on a 96 WS6. Here is the question, after reaidn it was suggested to replace the O2 sensor before starting to tune. Would it hurt to just replace the upstream sensor and not the downstream? I do not have cats on it and was going to turn off the downstream but wanted to make sure I wasn't screwing up or messing up some readings from it.

[bigtoyz]

i dont think OBD1 has the rear O2's......... thats part of the difference is. OBD2 added the O2's

[Fastbird]

The above is correct. OBDI doesn't use the after cat O2's. As for replacing......I'd only replace them if you've got issues. If they're working fine, leave well enough alone.

Posted from my Rooted and ICS'd Rezound

[meissen]

To add to Fastbird's post - take a look at o2 bung plugs. Right now you have 4 working o2 sensors and you only need 2. Personally, being the cheap ass that I am, I'd disconnect the two downstream o2 sensors, plug the o2 ports in the pipe with plugs, and then baggie the two downstream o2 sensors to save for a rainy day. Only do this when you're done with the conversion, though - while it's OBD2 you need them plugged in.

[bigtoyz]

Now this brings something interesting to mind. I just had my car up to the tuner. And he asked me if I wanted to shut off the rear O2's and said shit yeah do it.
When I got home I use LT1 Edit and he used my laptop to do it. I went in to see how and where he did it and couldnt find a thing. Can anyone verify this?

Due to some issues with him and me doing most of the tune and costing me 600 bucks for 3 dyno pulls and supposedly street tuning it and said I had it pretty close. But
still running rich at idle and cruising speeds he didn't adjust anything so.........I got a new sensor for my wideband and gonna do some math and get things where
they are suppose to be by modding the 400-2000 and 2000-7000 VE tables. WOT I had nailed at 13:1 (no boost as of now...selling the 600b procharger to add to the twin turbos funds)
and he added a little timing here and there. And really didnt get a full dyno pull cause it was breaking up at 3600 and told me plugs and opti might have something wrong with it. Got it home
trailered home looked at fuel gauge and put gas in it and spun to 6500 no problems ....what an idiot I'm thinking. But I got 250 rwhp at 3600 and 280 rwtq NA and still dont have a full pull number.
Not that it matters but just like to know how it did.

But when I get to putting my Twin turbos in this winter I found a new tuner cause I really dont want to go through that all again of tuning it again. I found a new
place to take it that is really up with the times and wants me to go E85 with the build.

Sorry for being to wordy!

[meissen]

Usually when they say they're "turning something off" what they really mean is they're disabling the flag for the o2 error codes. I don't have the definition file in front of me, but if you have upstream and downstream o2 flags, turn off the downstream o2 flags.