I flash my 01 z with the new VCM 4. I only added 3 degrees to cranking spark. Car is was going lean at idle. Very lean. Luckily I had my lap top and put it in open loop and it ran great. O2s worked grezat until this flash. I even flashed it to the orignal file before the cranking spark change and the O2s still were not switching properly.
Here is a log on the way to work showing the O2s switching when they want to.
I highly doubt both my O2s took a crap at the same time.