Questions after using code scanner

[So Bay Vetter]

I got an OBD II scanner (Carchip) to check my '96 LT4. I've changed the fuel filter which made a dramatic difference but it still feels like something's a bit off (missing, starving, maybe shorting a plug wire, idunno). Anyway, the scanner interfaces with my pc and allows me to monitor 23 different performance parameters (only 5 at a time though). I'm looking for answers to some of my readings.

The voltage on my O2 sensor constantly fluctuates (like every 2 seconds) up and down the scale from .01 to.09 volts. It seems to have no relevance to acceleration or RPM. Is that normal?

At 5500 rpm my throttle position was only 66% open (running lean?). Seems like it should have been 75-80% - or is throttle position related to miles per hour and not rpm?

Also I had no error codes at all. Is that even possible?

Any engine gurus with info? Thanx!!

 

[WhalePirot]

I am not a guru

The ECM's data, read by a scanner can bog us down with detail, which can hinder the troubleshooting process. The basics have not changed, such as ignition component condition, vacuum leaks, various sounds, etc. The myriad of voltages might reflect one of these basic troubles, but the road to the solution is quite long if we expect too much from this sole tool.

Run the car in a dark garage and look for arcing, if you expect a miss due to spark plug wire leakage. Listen and feel to see if the miss is regular, load related, only at high rpm, etc.

I use a vacuum gauge for troubleshooting. The better ones come with a guide that tells me what I am seeing with low or varying readings.