I have awesome grounds all over the battery and engine, including one on the VTEC solenoid itself. I also did the classic VTEC solenoid check of putting it to a 12V battery, and it did indeed click everytime. Before I swapped the tranny, the CEL would come on only when the engine was cold normally, occassionally on long trips. It didn't come on the first week after the tranny swap. Now it comes on all the time, warm, cold, whatever. I was told to check the VSS plug, the car has a mechanical VSS, so where is this connection? I assume it's between the Instrument Panel and the ECU, so is it somewhere behind the dash?

 

I also cleaned the screen and everything on the VTEC Solenoid, didn't help

 

bump

 

bump again, i really need to get this fixed

 

It turns out the VTEC solenoid itself had an intermittent connection, hence the intermittent failures. I replaced it with another B-Series VTEC Solenoid, and everything is solved. The bad one still passes all the tests with the 12V battery, and the filter is clean.