Tune related then

 

You heard of Thunder racing? That's who is tuning it.

 

Thunder Racing went and shut down a couple of years back, I didn't think they still existed as a business. Are you talking about EPS by chance?

If your fuel trims are swinging like you say they are, you should try putting LESS fuel in. You are quite possibly spraying unburnt fuel into the exhaust, which nets the exact same effect as having an air leak. Both will cause sensors to indicate a lean condition (rich only applies to having too much fuel for efficiency, but not so much fuel that it impedes complete burning).

 

Just throwing this out there, but anyway you have the O2 sensor wiring crossed? I fought an issue like this on a camaro where open loop ran great but as soon as it kicked into closed the trims went all crazy and ran like crap. Come to find out the O2 harness was crossed so bank 1 was reading bank 2 and vice versa. Switched it back around and bingo!

 

Thunder racing is out of business but the tuner from there still tunes.

I will throw less fuel at it an see what it does after I install my wideband

Both 02 sensors are in the the down pipe so they can't be crossed

 

on a single setup they are not supposed to be in the downpipe

on twin setups they can go in each down pipe but single setup they need to be before the turbo

 

Never had any problems with any of my other builds doing it this way

But I may move them if I can't figure anything else after I install my wideband.

 

Just to understand correctly, you have one down pipe and you have both O2 sensors in that pipe? I would suggest against that. A narrow band O2 will only read rich or lean, and it bounces back and forth between the two. When it senses lean it adds more fuel, when it senses rich it removes fuel. It does that for the entire bank. An engine doesn't constantly run stoich, it runs either rich or lean and bounces back and forth between the two. It sounds like that could be your problem. During the tuning process how was it running with the trims disabled? I would disable all trims and see what happens. But as Richard said earlier you really need a wideband to see what is happening.

 

Install narrowbands in correct locations
Next get correct data for injectors
Next make sure tuner has a clue


If this offends you then so be it....your fuel trims should never be that far out with a correctly built setup and correct tune

 

If your tuner can't get it right, try Geoff at EPS. He's the brains behind a lot of stuff in the LS tuning world and he started Thunder Racing.