Evo 3 16g surging at part throttle !

[brian9397gsx]

listen to ramsack, doesnt matter if its modded the top always goes to a boost/vacuum source the bottom goes to a boost only or in your case open to the atmosphere switch your source bet the problem goes away

 

[v8killer]

You're running speed density, it doesn't matter if it the BOV is open or not. A vacuum leak will be present no matter what as the charge pipes are basically at atmospheric pressure at idle, anyway. It's normal for a BOV to be open during idle, even without this mod, which is the main reason cars die when they are vent the BOV when running with a stock MAF. I read the article on that dodge mod once and I played out different situations in my head to try to understand it, and it seemed like complete crap to me. Trying to get a BOV that has equal surface areas on both sides of the diaphragm chambers is like polishing a turd. Sprung BOVs are used because they are simple and they are cheap. I'd suggest finding one that operates completely on pressure differential (HKS SSQV, Synapse, Toyota MR2 mk2, some Saabs I believe).

yes i know that it won't effect speed density i just didn't want it sucking in unfiltered air ! i had a fake greddy bov on my last talon and had it holding over 25lbs and it didn't open at idle or flutter like this also this car done it before i switched to SD, so that why i'm kinda stumped on why this car is doing it !

 

[ramsack]

I'm currently reading the article on the BOV mod and the guy even says that it is normal for it to be open during idle/cruise, which is why he has a picture of it with a air filter on the BOV. The mod still makes no sense to me whatsoever. It's just tapping a line to the charge pipe in reality. It's just a boost leak...

 

[ramsack]

so that why i'm kinda stumped on why this car is doing it !

Because there is no vacuum to fling open your BOV, as stated a bunch of times by a bunch of different people.

 

[brian9397gsx]

its hard for a vacuum operated valve to open when theres positive pressure on both sides

 

[ramsack]

Toyota part number 17670-88380 with 90925-01059 needed is probably the quickest BOV on the planet. They aren't cheap new, but used ones are cheap and none ever seem to die. They will also hold any amount of boost you can throw at it. In fact, the more boost you throw at it, the tighter it holds shut.

 

[v8killer]

Hey guys i fixed the surge by connecting the top port on the bov to the throttle body boost/vac port.