HI,

Yesterday I mounted my universal SQV BOV on my Scoupe.
Also attached the vacuum line to my inlet manifold.

But here's the problem: when I start my engine, I've got such
a strong vacuum ( -0.9 bar ) so that the vacuum pulls the valve
of the bov wide open, even if I adjust the bov spring to its maximum
stiffness. Now that the bov valve is pulled open when idle, it sucks
fresh air inside the turbo hoses. This air has not passed my MAF
sensor, so my ECU does not inject the correct amount of fuel.
Result: very bad idling and when shifting gears, my engine goes
below 500 rpm and sometimes completely stops running.

I had attached a foto of my setup, but on that foto you see my
old FORGE bov which worked well because these have dual valves so
when idle, the main valve is pulled open but the second valve is
still closed --> no air is sucked in.

Does anyone have an idea how I can solve this problem on my SQV bov?

Thanks for the help.

 

Sure, recirculate it m8.

 

-0.9 bar isnt alot of vacuum you should call HKS about it cause Stock SR20DET from nissan has an idle vacuum of -20 to -22 psi which is around -1.7 bar and alot of people use HKS SSQ bov on those engines and it works fine. i use blitz on my sr and never had a problem held up at -22psi and held up at +22psi lol

 

Than I don't have that woosh sound anymore

 

Nissans mass air flow is not as sensitive as most. I had a Blitz DD BOV on my SR and ran it with only minor idling issues. Look at the Evos. Their MAF is very sensitive which is why we have to recirculate. Its probably the same for the Scoupe as well. What is the Scoupe BTW? Not familar with it. Is it normally turbo'd or did you turbo it yourself? Just for now id try to recir it and see if that fixes it.

 

It is a Hyundai Scoupe, and is stock fitted with a garrett T15 turbo, but no intercooler. I mounted an intercooler myself.

 

Wow... That is a tiny turbo! If it is indeed a mass air flow system than try reciring the BOV. I dont see how that would cause it to idle at -.9 bar though. Its obviously leaking through the BOV like you said. Id just put your old one back on and see if its defective.

 

It's also just a little 1.5 liter engine
But with 150 bhp its fun to drive

 

You can try to take apart the HKS and shim the spring... or re-install the Forge