When I wired in my AEM UEGO wideband gauge/controller and sensor, I thought I was being pretty resourceful by using a cigarette lighter plug for power and ground, and the 0-5v output to the EGR Pintle input in the PCM for data logging. I didn't intend for it to be a permanent install because I figured I would only use it for tuning, then take it out until I needed to make adjustments for mods. The sensor pigtail is fished down through the existing shifter hole in the floor, and the wideband sensor is in the existing location for the narrowband sensor. I've disabled Closed Loop in the bin and have been tuning in Open Loop only so far.
Data logging has worked great so far, but I feel like I have a bug in my integration of the sensor. I have noticed that sometimes the value displayed on the gauge doesn't match what the data stream is seeing. I understand that there may be some lag between them, but for the most part they should be fairly close, within 0.1 or 0.2 of each other. Occasionally I see consistent 0.5 or so differences between readings. Enough so that when I use logged data to make VE adjustments, I bounce between lean and rich and never really settle near 14.7.
To the others around that use a wideband sensor and log data with the PCM, do you see swings in readings like this? Should I tap into the switched 12v and grounds used by the PCM for more consistent readings? If my power sourcing is adequate, do I need to plug in the lighter plug and let the gauge/sensor initialize before starting the engine, or is plugging it in after starting ok? What are your experiences with your equipment?