Boosting OBDII - O2 Sensors Locations

[BradsPGT]

So I think this is a simple question but maybe not. I am boosting my 1996 PGT and bought a replica Boostwerx kit so it has a 2 o2 bungs on the pipe, right below where it attaches to each of the OEM manifolds.

Now since I am using OBDI exhaust manifolds (because thats required with these pipes, right?) but its going on an OBDII car, it need 2 more bungs put in plus the wideband bung.

So if I put another bung on the turbo pipe, a few inches after (further downstream) the existing bungs is that good or should I try and have the shop put an o2 bung in each of the OBDI manifolds? And for the wideband, where is the best location to put the wideband bung in?

Hopefully that makes sense. I am taking the pipes to a local shop this week to get the welding done on them.

[short4stuff]

Where are they usually on obd2? one in each manifold and then in the y pipe after the pre cats in the manifolds?

If your boosting this, I am assuming your not worried about the check engine light? If your not, don't worry about the rear o2 sensors. put the two front sensors in the bungs that are there. and have a bung welded into the down pipe for the wideband. Mine is before the flex pipe around in around the 10 o-clock position per the manual.
Anything 18" past the turbo is ok. (also per the manual)

If you are going to be running megasquirt dont worry about any o2's other than the wideband.

[BradsPGT]

I'm running a Plug-N-Play MS unit wired into the back of a stock '96 ECU. I was more worried about emission and properly running, but you're saying I don't really need the other O2s eh? If plugging in the other couple O2s will rid CELs - which I don't know if it it since this is my first go at boost - but if it did, may be worth it.

As for stock O2s I can't say for 100% certainty since I have never looked at my rear bank sensors on this car yet, but the front has an O2 on the exhaust manifold, then like 2" below the manifold on the exhaust pipe so I'd imagine the rear is the same. And I would imagine there is also one after the main cat on the exhaust pipe. I haven't had a chance to get under the car and really give it a good look yet, just working on finish up finals for class the last couple weeks. I'll take a look at my Haynes manual when I get home, that may shed some light on it too. Or just wait till I have a chance to get under it and look.

Thanks for the input on location for the WB, that solves that part

[jleo_jleo]

I have a boosted 96 and faced this very same issue.. I ended up putting bungs in each side and have not had any issues. I'm not running MS.

[BradsPGT]

So you put added 2 more bungs into the turbo pipe? The pipes I bought have 1 bung just below each of the exhaust manifold flanges, 2 total?

I'm just not sure if I need to have 4 O2s on the turbo pipes or if those 2 are fine or if I need to have a shop put O2 sensors into the OBDI manifolds to replicate the placement like OBDII has.

[jleo_jleo]

Yes, I have 4 in total.. Didn't want to chance any CEL to stop me from passing inspection.

[BradsPGT]

Ok sweet, I was hoping someone had come across the issue before. So any advice on the location of the second bungs? Is a few inches downstream from the first O2 okay?

[jleo_jleo]

Yes, that should work as that's pretty much my setup too. I tried as closely as I could to duplicate the stock O2 locations, pre and post catalytic converter logs, except no logs! :-)

[BradsPGT]

Perfect. Thanks guys.

So O2s, try and replicate the OEM locations
And Wideband anywhere 18" after the turbo and before the flexpipe.

[short4stuff]

Maybe the earlier obd2 cars aren't as fussy, but with a newer car no cats going to throw a p0420. It checks to make sure the cat is there and functioning....

Otherwise your o2 locations seem ok.

[BradsPGT]

Yea I figured I may get a cat code because the OBDI manifolds dont have the 'precats' in them but we'll see. I'd like to avoid CELs but I'm not sure that is possible.

Anymore input is welcome. I think this pretty much answer my questions.

[jleo_jleo]

btw, I have no catalytic converts running currently.. Certainly no pre-cats because of my 93 exhaust manifolds, nor post since I went with 3" pipes and I have not had any catalytic-converted related CEL in running my setup. I've certainly had my share of CEL's but non related to the CATs..

[BradsPGT]

Oh yea? Awesome, thats good news then. I do expect my share of CELs too, hopefully sort out most of them