hello
what's the purpose of the pressure switch on the vtec body, and why some cars have a blanking bolt instead of it?

 

It is to let the ECU or PCM know there is sufficient oil pressure to activate the VTEC solenoid. If there is oil pressure then activating VTEC would allow the engine to rev higher than ~3Krpm, which would cause damage to the engine if the pressure was low.

From what I have seen, US built(USDM) cars have the pressure switch, Japanese built(USDM) cars do not have the pressure switch. Not sure if that is completely true, but that is what I have observed with CD Accords.

 

so non vtec cars can't rev higher than 3000 rpm?

 

That's not what he said.