i have aem ems on a fully built ls/vtec i have been searching for my problem as to why vtec does not work.
my question is
do i need a knock sensor for vtec to work?
right now i do not have one and i do not have vtec.
also i am running AEM EMS thats why i am unsure of this answer.....

 

There is a big misunderstanding as to wether VTEC will work without the Knock Sensor or a CEL Code 23 (KS) - from my personal experience (on my OBD1 H22A), VTEC does work without the KS and the Code 23 BUT it does not kick in as hard, which I believe is because the timing is retarded when you get a Code 23.

 

You dont need knock to for vtec to work. Aem is a full standalone you could make vtec come on with out any sensor for all that matters. You should read your aem manual to get a better understand of how it works.