The car is a 99 SI and my buddy says his VTEC sometimes doenst kick in at times but he has no CEL's...He thinks its a vacuum leak but does that really affect VTEC??? I wouldnt think so, but thats why Im here...Anyone have any ideas please help....Thanks

 

it could be a number of things...not enough oil pressure , bad vtec selenoid knock sensor...but your saying that hes not throwing any codes? hmm could be oil pressure..my friends used to do that...it would come on when it felt like..lol...but goodluck finding the problem

 

It won't work until the engine is warmed up also... Cleaning the screen on the VTEC solenoid is always an easy thing to try.

 

Yeah...**** found out what it was...didnt have enough oil in the engine...Period...he said didnt know that vtec used "oil" to activate...I should have informed him...