I know how vtec can be affected by electronics, but say someone does a bad valve adjustment, or put on a timing belt too lose, or something phycial to the engine, can vtec be affected???

 

VTEC won't be directly affected. BUT it will affect everything else like timing, valves, etc....

 

lack of oil or oil pressure can affect VTEC. The soleniod release oil in to the rocker arm rod, and down to pins in the rocker arm assembly which locks third vtec lobe into the timing of the two valves give you advance timing and third vtec cam profile. So im thinking a crack in the rod, or some kinda link in the head, or rocker-arm assembly can affect the profile of one valve thus throwing all the head off. later

 

Same concept about oil pickup problems........Sometimes if you abuse your oil pan too much you can bend the pickup and the vtec will not come on. Mine works but my pan is trashed from previous owner so I am changing mine soon.