Is a tial bov supposed to stay open on idle? Mine seems to stay open. And if u push gas it closes. Is this normal? Should I put a stiffer spring in it?

 

Check the TIAL spring chart and use the spring that correlates to your car's vacuum.

 

Okay I will do that, can u please explain what's the point if doing that? How come cars have different vacuum? What causes the vacuum to change

 

This is normal.

 

It's a bit difficult to explain without a boost gauge, but remember that an engine is an air pump. It's just built to withstand a flame front.

As stated before, this is normal. Cars will have different vacuums depending on the engine model. Strong vacuum is a sign of a healthy engine because the rings are sealing well. More aggressive cams with greater overlap can decrease vacuum.

Vacuum is useful for many subsystems in the car, but mainly the brake booster and sucking fumes out of your valve cover. In general, vacuum changes when you put your put on the gas, idle kicks up, or you turn on your AC. Or when the turbo wakes up...

 

Btw. Blow off valves are opened when in vaccum. Thats the reason they go pshhhhhh when you let off throttle or in between shifts.

 

they are always open when ur boost read negative. the vacuum line sucks the diaphram inside the bov

 

Thanks for the input guys, very helpful.