How accurate is the std O2S on an autometer gauge with flashy lights at wide open throttle ?? On a recent pass , the gauge was pegged on the lean side ... the very last LED was flashing ... I understand that under WOT the computer doesnt use the input from the O2S ... so I guess what I'm asking is does the ECM ignore the signal or cut off the power ... turn it off ??
Standard O2's are narrowband, meaning they operate on a 0-1v scale. Narrow band sensors only truly exist to allow the ecu to maintain a stoich ratio at idle and low load part throttle modes. The "flashy" lights are pretty much that..."flashy lights". Tuning a motor, either N/A or forced induction require the motor to be tuned marginally more rich than stoich (14.7:1). This is why wideband's are used. They operate within a 0-5v scale and generally read 10:1-20:1.
As for your question concerning what the ecu references, at wide opened throttle the ecu goes into an open loop mode, meaning it references the core maps directly with no input consideration from the O2, ECT, IAT, etc.
If your car is reading lean from a narrowband under wide opened throttle, then you potentially stand to gain some power by richening the mixture through tuning, fuel pressure, etc. Peak power for an N/A motor will come generally from 12.5:1-13.5:1, and a stock narrow band would interpret either as pegged full rich.
Please be advised I'm very new to Corvette applications, but have tuned well over 100 forced induction and N/A applications via standalone. Generally this information should apply, as ecu's all operate the same for the most part.
So ... in open loop or at wide open throttle ... is the 02S still able to provide feedback to the gauge / ECM ? ..... I understand the value of the wide band ... I just want to be able to ballpark the AFR with what I have since I can't spend any more money on the car ...
Well, the O2 is going to provide a signal to the gauge regardless whether the ecu is looking or not. The ECU doesn't cut power to the O2, it simply stops using the input to make changes to the air/fuel ratio at that moment.
Like I said, peak power is going to be made at an air/fuel that is richer than that narrow band has the ability to read. If your pegged lean according to that gauge though, it is likely your in the 15:1 range, which is quite lean for wot and full load. A fuel pressure regulator or some form of management to alter the amount of fuel the motor sees would help make more power.
I must warn you though, that wiring the autometer gauges has been known to create interference with the ecu signal if the gauge isn't grounded properly. Something to keep in mind.
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