ok here goes........

on a sohc vtec motor you have 2 exhaust lobes on the cam as well as 3 intake lobes on the cam. during low rpm driving(generally below 5500rpm) the motor acts just like a non-vtec engine. keeping within the strict emissions standards that were set for that model year car. ok on to vtec, when the engine is driven(not just revved) to 5500 rpm or higher the computer starts to read applicable sensors (vehicle speed sensor, vtec oil pressure switch, coolant temp switch, ect.....) and if everything checks out ok then it opens the vtec selonoid and sends oil to the rocker assembly hence activating the third intake lobe on the cam. now most generally know that the vtec lobes are of increased lift and duration. while also at the same time the ecu also adjusts the fuel delivery and timing to match the vtec lobes greater lift and duration. so basically at 5500 rpm it just like swapping out your camshaft for one that has more aggressive profiles.

like i mentioned before, vtec will not engage if the car is not motion. this is where the VSS comes into play. vtec will not engage if oil pressure is low, and i have also heard that it will not engage if the coolant temp is not correct. (im not for certain on that last one??)

well i hope that this has helped you understand all that is vtec!

stay tuned people...next week we will discuss the new and improved vtec-i or possibly the gas mizer vtec-e. thank you for tuning in for this edition of CHAMORRO MOTOR SPORTS. see ya next week!