I have just finished a transplant hybrid, b18c into ef sedan which i had also had previously and have no codes, good oil press but i think the thermostat not acting right so replaced today but snow on so could not check....

can bad thermostat knock out VTEC activation??

 

If the thermostat were stuck open, and it was very cold out, and the engine never got to operating temp, then yes vtec would not engage.

 

no engine easily (too easily?) got up to operating temp. and would go too high, at least by idiot gauge standard if held at 5k+ rpm on the beltway

i know it requires operating temp of i think 175 F but i easily got that

well, replaced that bi--- anyway but now am stuck in the garage with too much snow here in VA

funny how i had it before replacing the shortblock and otherwise keeping the ECU and electronics identical

any other ideas?

 

another possiblility could be low oil pressure.

 

no plenty of oil and plenty of oil pressure as even at idle it does not go below 38 psi but increases to above 60 psi at 5k rpm which would be my VTEC point for right now

i disassembled the vtec and gasket plus filter and the mechanical device itself fine - it was also working perfectly before i freshened the shortblock and reassembled