1. even though i am running neptune, and have an aem wideband as well as a greddy, can i still use my stock 02 sensor to monitor my exhaust gases, or is that why the widebands were used? asking this for emissions reasons.

2. can you still run those same emissions if you cancel the o2 the computer looks for and still run vtec? or would that be pointless?

 

You should use a wideband to monitor your lamda/air fuel ratios
The narrowband o2 sensor can be eliminated without side effects.

 

and the car will still remain under the emissions the p28(assuming thats the ecu being used) has it set at or does the tuning take care of that as well?

 

If you eliminate the narrowband and disable the o2 sensor, the answer is no

 

no to what? no vtak when narrowband is disabled?

 

no longer emissions legal. You can still run the 1v output from your wideband(asuming it has one) to your ECU to act as narrowband emulation for closed loop. However, you would still need to disable the O2 sensor/heater in Neptune to stop the CEL.

 

vtec functioning has nothing to do with o2 feedback.

 

was always guided under the fact that once the o2 went out, the car went into "safe mode" and disabled the vtec.

 

The O2 not functioning causes it to be in open loop. The ECU is already always in open loop during VTEC.

 

Alot of good info in here.

Side question... Whats the most accurate input for wideband use (Neptune). Is it ELD with resistors clipped? Is this most commonly used?

 

ELD with resistors clipped or EGR Lift seems to be the consensus.

 

defined version of "eld" please if any one can answer.

 

Electronic Load Detector and pin #D10