1. What makes the O2 sensor "ready" on my autoxray scanner? Is it voltage or what? Seems my 92 Z28 O2 sensor reads "ready" almost immediately upon start up with low mv readings.
2. Is there a certain voltage on the O2 sensor that triggers closed loop mode? My ZZ4 only seems to drop into closed loop if the O2 sensor can maintain 600mv or higher.
3. What do the voltages mean, i.e. is 300mv rich and 600mv lean?
4. What would a stock L98, iron manifolds show on a properly operating O2 sensor.
5. Can you reprogram the prom to trigger closed loop at a lower O2 mv? I'd love to have mine trigger at 500mv. That would probably solve all my problems
Thanks

 

The o2 sensor has to be warmed up enough to give accurate reads-I don't remember the temp though-?300deg?? If you have a one wire (non-heated) sensor it needs to be closer to the heads to warm up; if its too far away you'll keep going open loop. Thats why if you place it further away you'll need a heated o2 sensor. And yes, there are tables in the prom for times to go closed loop, but the sensor still has to be warm enough. Less than 450mv is lean and over 450mv is richer than 14.7:1. I know this is a real brief overview, but hope it helps.

 

I have a heated O2 sensor, wired correctly.
How does the ECM sense the "heat" of the sensor?

 

The O2 sensor is what is heated. The sensor has to get to a certain temperature (don't remeber what it is, but it's pretty hot) for it to function (Oxygen in exhaust reacts with I can't remember what to produce electricity. It's actually a very simple--just a chemical reaction.) I don't have my book that lists all this stuff with me right now but I'll post later. There are 4 conditions that must be met for the car to go into closed loop mode (enrich/lean based on O2 sensor data).