Speaking of oxygen sensors....

[Rich Z]

How many people use a wideband in first one bank for tuning, and then check the other bank? Seems that since there is an oxygen sensor in each bank that operates independently, isn't this telling me something? If it isn't important, then why not just have a single oxygen sensor and call it a day? I would think the car manufacturers would love to cut manufacturing expenses if something was just frivolous and unneeded.

Along these same thoughts, can dual LC-1 WBs be used with EFILive to monitor both banks simultaneously? Or has it been proven to just be a waste of time and expense doing it this way instead of just swapping the WB from one bank to the other?

[eficalibrator]

As long as a few ASSumptions are good, you "should" be fine with only measuring one bank:

1) The intake manifold is designed as a mirror that does not bias air flow toward one bank
2) Valve events are timed the same on both banks (more of a concern on OHC engines)
3) Injectors and rail pressure are the same for both banks
4) Measured injector pulsewidth is the same for both banks as seen in the datalogs
5) No vacuum or exhaust leaks in the system

If all of these are good, then it's reasonable to assume that both banks would be operating the same and burning at the same AFR. FWIW, you might see two different AFR numbers with cheaper widebands like the LC1/LM1 since their control logic is sketchy at best anyway. Don't confuse poor O2 sensor control/reading with variance in actual engine performance. Also, understand that combustion itself is only ~2% consistent, so it'll never read perfect even with a lab grade O2.

[Rich Z]

Yeah, theoretically. But how come mistakenly crossing the harnesses for the front oxygen sensors is a common cause of people causing their cars to run incorrectly? If the banks were mirror images, I would expect something like this to have no effect at all. Perhaps the points you made are not as easy to hit as we could assume?

[joecar]

When the front O2 harnesses are crossed, then as the PCM trims each bank differently (say one negative and the other positive) it sees the opposite effect (since the harnesses are crossed) so it keeps increasing the magnitudes of the trims (the negative bank becomes more negative, the positive bank becomes more positive) and it keeps seeing the opposite effect in a recursive manner...

this is closed loop positive feedback very much like holding a microphone close to the speaker it feeds (the signal/trim becomes grossly unstable and diverges).

[EagleMark]

I've done a tune with LC-1 and then swapped banks and data was almost mirror identical. If there's no mechanical issue bank to bank there should be no change as already discussed.

Dual O2 sensors were introduced in V engines as part of bank to bank or Sequential injection, as Joe discibed feedback for each bank. Can't swap feedback bank to bank.

Sequential was first introduced IIRC for emissions at idle and low RPM. Most notably the 94 LT1 which would pass 97 emissions if it had crank sensor for misfire, but emissions were covered. Just as heated O2 sensors were introduced to keep Closed Loop Idle for emissions. Many cars would idle in inspection lines and cool off go Open Loop then fail emissions because of idling so long, really bad on TBI wet intakes...

[Rich Z]

So on a 2002 Corvette Z06, which way should the front O2 sensors be hooked up? I've heard people say crossed over (passenger side sensor to driver side harness, driver side sensor to passenger side harness, which LOOKS like it would be correct because the sensors are actually pointing in the opposite directions when installed in the bungs), and others say straight to the side the sensors are located on. Obviously they both can't be correct, but which one actually is the correct way? Mine are installed straight. Passenger side sensor to passenger side harness, driver side sensor to driver side harness.

[Mr. P.]

Check the GM service manual for wiring system routing; you gotta be sure, there is only one (correct) way to wire the sensors!

[Rich Z]

Jeez... The GM service manuals are an abomination. Yeah the information is all in there, but whoever created the index for those manuals spent way too much time breathing exhaust fumes. Every time I have to look for something I have to basically browse through the manuals till I stumble across the pertinent section. :( I had to completely replumb by fuel system since the guy who worked on it had it so screwed up that the passenger side tank wasn't even hooked up. Took me forever to find everything I needed to get that fixed. So honestly, I'd rather get a root canal than to use them.

Which is why I was hoping someone would KNOW the answer. Anybody?

Or is there a CD or DVD version of those service manuals that has a decent search function incorporated with the info?