hippy

I just purchased an AEM wideband for my 05 LS2 with a full Z06 exhaust. The exhaust still has the cats and I plan to keep them. The H pipe when I bought the exhaust had a bung welded in it far forward left side of the H pipe. I am currently using that bung for my O2 which places it after the cat. I know this isn't ideal but with the Z06 manifolds there really isn't a great place for another bung before the cat. At part throttle I am seeing 14.6-7 so that's fine but I've logged my car with probably 20 runs in 2nd and 3rd gear and am seeing varying O2 data. I saw just one run that went up to 13.2 between 5750 and 6500, which was the first run I did on that log and that one run was leaner throughout the whole rpm range than every other run to redline which also was a 2nd gear pull. All the other runs stayed below 12.6 and down to 11.8 hovering around 11.9-12.2. Should I continue to try to tweak the tune closer to 12.5 even though I did see the one run go lean, or should I be cautious of the data that sensor is providing me due to its location? I am also using HP tuners.

[img]<a href="http://s1120.photobucket.com/user/hippy289/media/screenshot.jpg.html" target="_blank"><img src="http://i1120.photobucket.com/albums/l481/hippy289/screenshot.jpg" border="0" alt=" photo screenshot.jpg"/></a>[/img]

erick_e

It can be done..

hippy

I saw this in the directions though and it seems they don't recommend the sensor mounted that close to the exhaust port.


A weld-in M18 X 1.5 boss is supplied for sensor installation.
Mount the O2 sensor in the exhaust system at least 18 inches downstream from the exhaust port.

erick_e

Not too many options when keeping it upstream of the cats with OEM manifolds.

NGK recommends 12-48" from the engine. The closer it is to the engine, the more chance it has of burning out from overheating. But in all cases pre-converter it probably best.

schpenxel

I've done it on both LS2 and LS7 manifolds.

On LS7 I put it basically on the opposite side of the pipe from where the factory one is (pre-cat). It fits fine. Muffler shop welded it in in less than 30 minutes so it's not hard.

LS2 I put right at the entrance of the cat. Again.. both worked fine

I can get you some pictures if you need them

YOU NEED IT TO BE BEFORE THE CATS!!

Lots of things can cause different AFR's during different pulls. Transient fueling can do weird things, IAT's being different can cause things to change sometimes.. long term fuel trims can carry into WOT and make it go richer.. all kinds of things. Some are tougher to see than others.

Regardless, get the wideband installed before the cats first.

hippy

Did you have them weld it with the pipe in the car?

schpenxel

I did on the LS7 ones

LS2's I took off and took to a machine shop.. though a muffler shop could have done it in car no problem

LS7 ones have been in for about 6 months, used nearly daily.. no problems with the wideband O2 sensor

hippy

I have a 2nd set of down pipes I could just take in and have welded but if I don't have to pull the down pipe off that would be nice. I'm assuming they weld from under the hood and not under the car. Would that be correct?

schpenxel

No. From under the car.

I'd have it done on the car if possible. I actually had one set of bungs installed (off the car) after I thought I had carefully picked a location that would work.. yeah, ended up not fitting. Had to have them re-done. The redo was the one I had done on the car at an exhaust shop. I just showed up randomly one morning at 8:30 and was gone by 9. Cost me $40 I think it was

hippy

I wouldn't have guessed that you could get a bung on under the car, but it's been a six months since I put the exhaust on. I'll put it on the lift and take a peek at it one of these days.

schpenxel

There's more room than you'd think, just have to install it at the right angle

If you need pics to help the installer I can to get some next weekend

hippy

Yea, if you're going to have the car up in the air I'd be interested where you put it.

schpenxel

Will do.

truth.b

sub'd

Mike's LS3

Do a search, Josh from A&A corvette posted several pictures on the F/I platform of the sensor bung placement prior to the cats for C5 and C6 vettes. The sensor should be placed at a 15* angle pointing down. This prevents moisture from getting on the tip of the sensor which will damage it. You can buy a bung cut at an angle to help get the proper angle for the sensor.

schpenxel

Ideally, yes. But the world won't come to a stop if it isn't installed perfectly.

Mike's LS3

Mine isn't perfect, but I really don't want to spend $100 for a new sensor down the road. I finally upgraded my Hptuners interface to the Pro version so I can now log using the PLX WB.

KM177122

Sub'd. Interesting to hear the various areas to place.

schpenxel

Wideband on LS7 manifolds, before the cats, driver side. Muffler shop welded this in in < 30 minutes for like $20-30. There's another bung without a sensor which is what happens when you try to install a bung with the exhaust off the car, so ignore that little mistake

hippy

Thanks for the pic. It's getting to be that time of year where I will start driving it again full time and get this done.