Blow off valve open at idle
 

Hey guys, just finished installing the JDL turbo kit. My issue is that the BOV stays open at idle, even after tightening it down all the way ("hardest" setting). My line for the bov is T'd in to the brake booster line, before the check valve, as many instructions said to do. However, following this line does not lead to the intake manifold, but to a port on the passenger side of the block. I have a 2013 automatic FRS, and since researching a bit have seen indication that the automatic may be different than the manual in this regard. Can anyone tell me if I'm T'd in to the wrong line, and if so, where I should tap into on an automatic car? I was told I may need a stiffer spring for the BOV, but that seems strange considering the quality of this kit.

Pictures: https://imgur.com/a/tlsi3M3

Edit: couldn't figure out how to add a picture to the other album so here's one with the block port I mentioned circled.
https://imgur.com/a/BJipqtY

Yeah the autos have different routing for the brake booster lines. On the top/back of the intake manifold, there are two ports for vacuum lines. One will be capped off on your car. You can run the line to there. I ran a tee there for my gauge and BOV and it works fine.


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Thanks, so just to clarify, I would run the bov line directly to the capped off port on the back of the intake manifold? And I'd just need an adapter of some sort?Since I'm pretty sure that port is way bigger than the bov hose. And you just had a tee since you had the boost gauge as well, I presume.

Yeah that's exactly what I did. I think on the manual cars that's where the brake booster line goes instead of into the block like the autos. I got one of those universal cut to size tees from autozone so i could run a larger hose to the tee and smaller hoses off of it. They also make cut to size straight adapters you can use.

Hey, so I did just that - ran a short 4-5" section of hose from the other intake manifold port to a 3/8" to 3/16" reducer connector, then connected that directly to the BOV line. Both ends are clamped tightly, but I am getting turbo flutter when I let off the accelerator. The BOV is set to the softest setting possible while still completely covering the o-ring indicator. Did this happen to you? Any idea what the issue may be?

Yeah my BOV will flutter when it’s only under a few psi. At like 10psi it’s more of a single loud sound. I don’t believe there’s anything to worry about with it and it’s more attributed to the style of BOV. If it’s staying closed under acceleration and properly releasing when you let off, it’s doing its job. The bad kind of turbo flutter is when your turbo is pumping so much air into the engine that it can’t take it all and then it starts pushing back on the compressor, creating a fluttering sound.


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This isn't a thing. It's called forced induction because it adds air that the engine can't refuse, if it can't hold it the engine blows. The chopping/flutter sound is when the throttle body slams closed and the blow off/bypass valve on the intake piping can't evacuate the air fast enough.

What are the solutions to getting the BOV to open under less pressure? More vacuum/softer spring? From what I can figure, the only thing that would create more vacuum is a higher displacement engine. And what would I have to worry about with a softer spring? The BOV opening prematurely under low boost?

Yeah you could try a softer spring, but too soft and it won't close. It should be completely closed at idle. The way it works is when you are accelerating, the pressure in the charge pipe is pushing to open it, but the engine/vacuum line are also pressurized, helping hold it shut along with the spring. When you let off throttle, the engine is quickly under vacuum again while the charge pipe is still pressurized, so the valve gives way and opens. I dunno if you have a tial bov or another brand, but if you search around, you can find how much vacuum the engine pulls at idle and which color spring that corresponds with.