I hate to beat topics to death, but I'm not too happy with my search results in finding a variety of information...so I'm going to beat this horse again.

Where is the best spot to put a wideband to get the most accurate readings on an 02 ls1? I know as close to the header as possible, but should I be looking to run dual widebands?

I know I have read that the driver side has leaner banks than the passenger side, so should I be putting the wideband on that pipe if I am going to run a single sensor?

Do we have the ability to skew fueling if I do run dual widebands and determine one side is leaner?

Lastly, we have like 6 o2 sensors in these cars. I know I can unplug and use one of these ports, but I can't remember now, is it before the cat or after the cat?

 

The closer the better for accurate readings. Further away is better for sensor durability. Innovate suggested 18" from my turbo. I have noticed the reading lags one frame behind in my logs mounted so far away from the cylinder head.

Dual widebands would be best, but you can get away with one. I can't speak from experience on the skewing one side in the tune on an LS1B but I think you can. The narrow bands certainly do automatically.

The WO2 has to be before the catalytic convertor.

What tuning software are you going to use? I don't think there are 6 O2 sensors. My LC-1 has the ability to fake a NB signal if I had placed it in a front O2 factory position.

 

Thanks for the reply, sorry for the late response...it has been a long week.

So am I ok to unplug the narrowband right before the cat on the drivers side? or does the car heavily rely on that one?

I am using hp tuners for all tuning.

I know there is 1 sensor before/after each cat, and I thought I saw one further down stream, so I threw an extra one in for good measure

 

Don't touch the narrowbands as they are needed for closed loop. Put it a few inches away from it up or downstream on the driver side pipe. Closer to the engine the better due to the infamous #7.

 

so I can't replace an existing sensor and I need to add a bung?

 

Replace an existing sensor? I'm lost. Get a muffler shop to weld in a bung for you wideband O2 sensor on the driver side pipe pre-cat.

 

This is what I have noticed over the years for wideband placement. I've noticed that some headers place the 02 sensor very close in the collector to where the primaries merge into the collector. The problem with using that bung for a wideband is you get a lot of data and reversion from one cylinder with the o2 being so close to one or two primaries. I normally like to place the sensor anywhere from 8" up to 20" from where the primaries merge up in the collector. Under WOT the only place you'll really notice a lag is low rpm where intake velocity and exhaust velocity is down but as RPM increases the o2 becomes much more accurate to where you currently are on the table.

If single sensor put it in the driver side, if you are running dual sensors then obviously one in each. You can also pull the rear o2's and use the bung for them to put your wideband(s) in. It'll still read fine back there as long as you don't have exhaust leaks or a cutout in front of the rear o2's.

 

You can't run the wideband after the cat or it will scew your readings. If you are going to wideband tune you will be open loop so you could put it in place of the front O2 while tuning.

 

I say remove the #1 O2 on drivers side, tune it, then re-install NB sensor and call it a day. I had access to cylinder skew in my v6 but don't think we have that option in the LS1. Wish we did, I'd love to have the ability to skew that #7 as mentioned above.
If anyone has info on the ability to skew that #7 I would be very, very interested

 

For what it's worth. When I had my car dyno tuned they stuck a wideband in the tail pipe and it read .1-.2 richer than what mine showed and mine is actually mounted on the neck (pre cat) of the high flow catalytic conv.

 

That is how I know about skewing, from the 3.8. I figured since the ls1 pcms have 100000 more tables than the 3.8's, that this would be an option buried somewhere I just haven't found.


back in my v6 the car had 3 o2 sensors, 1 right after each header, and one right before the cat. The one right before the cat wasn't really needed, so it was ok to unplug/delete/replace that O2 with a wideband sensor.

I was hoping it would be the same for the ls1- I don't want to tune then delete the wideband, I run it full time- I like to know what is happening 24/7 while driving my car (I caught that I was having a clogged fuel filter just doing a base scan of my car at WOT and the narrowbands showed I was lean. The car ran great though, without that data, I would not of known and possibly done damage until it got bad enough that the car bucked and I had to investigate)

Since I will also be installing longtube headers over the winter, maybe I'll set it up as the same way the v6 was. Move down to a single cat and place the sensor right there so it gets both banks.

At the end of the day, if we can't skew, there isn't a huge point in running dual widebands imo.

 

Will your wideband fake a narrow band signal?

 

Mine uses a bung welded into the I-pipe at the trailing
edge of the passenger's door.

 

it is a AEM, I don't think so. But, if you have hp tuners, why would faking that signal matter anyways?

 

Depends on your tuning technique. You can fail the fuel trims and tune it pure open loop. I didn't.

It's not that it is faking the signal, but rather providing a compatible signal to the ECM at the same time.

 

That's the way I always do it. And on vehicles with cats that are bolted directly to the manifolds, there is no practical way to weld in an O2 bug.

Russ Kemp

 

I don't normally have a problem with cat's here in KY as we don't have any emissions here so that is the best mod to do is to take a broom handle to the cats or put off road headers and a x or y pipe (depending on type of vehicle).

 

And the stink of a cat-less vehicle gets old real quick. Installing high flow cats on a street driven vehicle costs very little HP.

And I don't get why you would want make a late model vehicle's exhaust smell like an old car. A functioning catalytic converter significantly reduces emissions. And where I live, there are no emission tests either.

Russ Kemp

 

in general...replacing a stock Front O2 is the Easiest way for tuning...Turn off and reset stock Trims, dont worry about the o2 code while tuning....
but..if you are going to add a bung for another o2... anywhere from 12-18 inches from the collector is usually acceptable for reasonably accurate readings....
the further back you have to go, the further from the exact same frame its going to get while tuning...which translates to data being a little bit off in the tune and just making it harder to get a tune done quickly.

the Cats dont skew readings on a Wideband.....
I've done a bunch of tunes with wideband after the Cats.....
the only time a Catalytic Converter burns fuel in the exhaust is when you have so much that it is PIG rich which causes the cat to overheat, and that excess heat will eventually reach a temperature to cause combustion inside your exhaust....it wont get there in normal operation or anything within the normal operating ranges that we use for tuning.

I've also tested this on the dyno with one before and one after...multiple cars, from stock to aftermarket cats.... no difference from before to after...only the difference in lag from front of car to rear of car. (meaning 13.0 in front, 2-3 frames later I see 13.0 at the tail pipe.


you can buy a wideband that will output both a 0-5v signal, and a 0-1v signal(programmed for 450mv to be 14.68 afr or 1.0 lambda) and send the 0-5v to the tuning program, and the 0-1v signal over to the pcm

in an ideal world, you have one on each side...and then you pick a method to tune....tune to the richest? tune to the leanest? tune to an average of both?
there are various reasons for all choices.
when you get to an aftermarket pcm like the Holley EFI stuff, you can tune each cylinder and make it so that you can get even fueling from bank to bank, or just fixing front to back fueling....but you have to use more tools to determine that stuff(more widebands or EGT probes.)...

 

Good to know, thanks