Your thinking of it backwards. What are you stft values? You sdjust the switchpoint to line up your trims.

 

The STFT's bounce around zero while cruising (when I have lean cruise disabled). Are you saying vary the switchpoints between banks so the STFT's of both banks are about equal? Sorry for the confusion. Mine vary slightly from bank to bank, not sure how much through.

What I was trying to say is, lets assume my wideband is 100% accurate. When the narrow band O2's are targeting what they think is stoich, the wideband is reading 1.00-1.02 (0-2%) lean. So couldn't I adjust the switchpoints so when the NBO2's are targeting stoich the wideband reads 1.00?

 

I guess I do it way different than you guys. I use the Narrowbands to tune idle and part throttle in the VE. They know stoich better than the wideband does. And then I use the wideband for any tuning done where I want to target something richer/leaner than stoich.

 

I've never heard this before. Is it because the NBO2's are more sensitive to stoich (in terms of output voltage) than a wideband?

 

No. With the trims turned on you wideband will read real close to 1.00 because the trims force it there. Now since the trims are pushing your afr to 1.00, look to see what your trims are reading. At part throttle with trims a tive your wideband is useless, read the trims.

 

A narrowbands only purpose is to find stoich. They have a very "narrow" window that they function in. I will always use a more precise tool if there is one handy.

 

Exactly how I do it.

 

Chasing the rabbit does not allow you to catch it.
If tweaking the switching works sounds like a fix.
Figure the engine is no longer oem spec once your hot rodding starts.

 

I'm going to get a log here in a minute so you guys can see what I mean. I'm thinking that I'm just going to have to tune idle and part throttle with the wideband so I don't get the lean condition on cold starts and warm up. That will make my STFT's wack but they still get fueling in line once closed loop hits. I'm sure thats the best I can do with how the O2's are positioned

 

Here is a log at 10-11psi. You can see that my histogram is fairly close. Not perfect but the STFT are within 3% everywhere. Now if you look at the log, bank one (O2 is close to stock location) stays pretty consistent. Bank two is all over the place. I think I saw it adding 14% somewhere in the log . I've never seen bank two subtract fuel, it is always adding.

It sounds like having the bank two O2 post turbo is just not a good place for it from a tuning standpoint. Don't get me wrong, it works and controls fueling back to lambda 1 but if I listen to the STFT, my tune will never be correct.