I just finished my ls vtec swap, fully built n/a b18a bottom end, b16a2 head. P28 chipped to a p30. Had it towed to get tuned, and they couldn't get vtec to work. All sensors are connected, knock-vps, and vs. I have 12v at the vtec solenoid when vtec rpm is reached but engine doesn't switch to highcam. Oil pressure is 55 psi at the head. what am i missing? need some honda tech help.

 

Is the solenoid good, and is the correct setting marked in the tuning program, and how about the coolant temp sensor?

 

if the coolant temp sensor was bad, would i still see 12v at the solenoid- i also ran 12 v directly to the solenoid and it clicks- the ecu is chipped but still not tuned- the tuning guys put a vtec window from 4600 -7900

 

a certain coolant temp is needed for vtec to work also, but if its clicking that means its workings doesnt it? Problem may lay in the internals of the head.

 

how are you measuring pressure at the head? and what size line are you running? where are you tapping into the the head at? i had a problem like this once and pressure was not getting to the to keep vtec engaged

 

do you know which coolant temp sensor? after all the wiring is tripple checked- i have no other choice but to start pulling the head apart-

 

I thought there was only one, on the side of the head, but if the sol. clicking i doubt thats the problem, and therefore think its inside the head.

 

i tapped the head on the passenger side rear of the head, the line goes straight to the T fitting which shares the same port as the oil pressure sensor. I believe the line is 3/8- i'm measuring the pressure at the pressure line going into the head with a pressure guage- what size line should i use? and what did you do to correct this because its driving me nuts-

 

just brain storming here. did you do all the ls/vtec stuff? plug the head? tap the head? did you tap the head on the pss backside top right by the dist?

stupid question maybe low on oil?

just trying to throw stuff out there

 

the bigger the line the more pressure your gonna need? what oil pump are you using? i ran a vtec oil pump and ran a -4 line. with a smaller line the less volume you will need to keep the head suplied with oil

 

i built the engine, i'm familiar with alot of swaps but this ls vtec is my first. the car has plenty of oil, so your saying use a smaller line to increase oil pressure?

 

yes, there is a difference between pressure and volume

 

kinda like if you stick your thumb over a water hose, what happens? the pressure of the water increases