Kia Forte Turbo Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
14 Posts
Discussion Starter · #1 ·
Did the ol' recirc hose removal to get that sweet sweet PSSHSHH! But now that i can hear it, i notice things that seem off.

First, under higher loads, sometimes there is a loud "thud" that comes with the blowoff. best i can describe the sound is a rubber hose whacking against the ground. I took the recirc hose completely out, so it's not flailing about under the hood.

More often though, is again coming off harder acceleration, the blowoff makes a double shot, a short hiss, breif pause, then the rest of it dumps as normal.

3rd, under normal accelerating, coming off throttle to either coast or slow down, the amount of time it dumps boost for seems to change. either it keeps venting right down to idle, with the hiss becoming almost inaudible, or it dumps until it gets fairly quiet, then abruptly closes the valve. It doesn't feel any different between these 2 driving wise, but inconsistent sounds make me concerned.

Just replaced the MAP on the intake with the 39300 84400, trying to get my fuel mileage back up to something normal.
 

·
Registered
Joined
·
53 Posts
I'd assume it's because the BOV is some fan dangled electronic one. I've experienced all 3 issues and from what I've researched its normal.

Could changing the stock valve to a better one stop all the weird sounds? Someone with an aftermarket one might need to answer that.
 

·
Registered
Joined
·
1,697 Posts
Changing MAP will not really make your fuel economy any better... :) it is your foot.
Unless MAP was broken.

As for the sound.
There is no one good sound. It depends how quickly you move your foot off the gas, what RPM you are at... I could even get no dump (no audible one) when going from WOT to coast if I moved my foot slowly enough.

And the dumping noise - normal. At least that is what I hear.
The thud is the 18 psi of pressure that is being released. Then is air flow. It's just a sound wave. OEM BOV does not have sound plates or anything. It is simply a rubber valve.


Problem is when you hear it venting when you are under WOT.


Only the second case is confusing to me.
 

·
Registered
Joined
·
14 Posts
Discussion Starter · #4 ·
yeah the double hiss is odd.

Fuel economy died in december, i'm trying to get it back to more normal amounts, since 2 dealers told me nothing is wrong. I'll get maybe 450 KM to a tank, even doing more than half of that at highway speeds.
 

·
Registered
Joined
·
1,697 Posts
I found that this beast, especially AT, is very sensitive to ambient temperatures. If it is anything below 10 C when cold starting, fuel economy suffers. Winter, with -10 C - that was very bad.
2015 MT I had was much better, but still was very thirsty.
 

·
Registered
Joined
·
534 Posts
For the double hiss it is due to the snow solenoid that controls the bov. They sell an upgraded one that reacts faster and should stop that double hiss.

Also the bov releases under a difference in pressure. Boost pushes the valve closed but adding to the spring pressure that normally keeps the Piston down. When you close the throttle plate there is no more boost in the plenum but still some on the other side of the throttle. And since boost from the plenum is what was keeping the Piston closed and now there is a vacuum pulling on the Piston the positive pressure at the bov can now push the Piston open. But here is a good video

https://youtu.be/lI9rJoNzNVc
 
1 - 8 of 8 Posts
Top