zguy36 Posted April 1, 2006 Share Posted April 1, 2006 I am about fed up with my greddy type-R bov and was wondering if anyone else has had these bov problems. The problem is that the valve doesn't actuate correctly. It has two line ports on it.. the top one that goes after the throttle body and the bottom one that goes before the throttle body. If I want to run more than 10 psi of boost, I have to tighten the adjustment screw on the bov so tightly that it won't blow off with lower boost pressures. This translates to turbo surge all the time during normal driving, which is quite annoying! If I loosen it up enough that it opens correctly, then at high boost levels 15psi, the valve opens even when the throttle is wide open and leaks off my boost pressure. Has anyone else had these problems? I have taken the valve apart and there is not a thing wrong with it. I also had similar problems with the greddy type-s bov (thats why I changed to the type-r) Quote Link to comment Share on other sites More sharing options...
AnTmanS130T Posted April 1, 2006 Share Posted April 1, 2006 I have had this problem for a long time, talk about frustrating. I notice with the both lines used, the valve leaks and causes the car to bog down as the rpm's go up. Right now I have the type- s on the car .. for about 15psi .. I have the valve pretty tight but not all the way. This allows lower boost to vent and allows the valve to hold shut and not blow open at the higher boost..like it has a billion times. It's just all about getting the tension right for a certain amount of boost. It's a real pain in the *** and real annoying. Quote Link to comment Share on other sites More sharing options...
zguy36 Posted April 1, 2006 Author Share Posted April 1, 2006 for below 15psi, I can get the valve adjusted to work correctly, but I don't want to run that little boost! Above 15psi, the darn thing just won't work right no matter how much tweaking I do to it. Frustrating as hell! Things that I think might be causing me problems with this are the small stock throttle body. My intercooler pipe is 2.5inches, and the small stock throttle body is around 2inches. My thoughts are that there is a couple psi pressure drop across the throttle body resulting in a pressure differential between the two reference ports on the BOV. If these two ports don't have the same pressure in them, then the valve will try to open. Which reminds me that I have already thought about this.... My attempt to correct that problem was to put both reference signal lines from the throttle body. With both lines inside the throttle body, both of them should recieve the same pressure.... which leads me to the next though... If both lines are inside the throttle body, then they will be at a lower pressure than the valve face of the BOV. The type-r bov has a really large valve face, which equates to quite a bit of pressure trying to open it. Since the throttle body is small, and before and after the throttle body is large, this is in essence a venturi, which gives lower pressure inside the venturi than outside the venturi. This would have lower line pressures in the reference ports than at the valve face..... which leads me to my last thought of that it shouldn't matter. If both sides of the diaphram inside of the BOV are the same surface area, then the force should cancel out as long as the pressure is the same on both sides, which it SHOULD BE! ANy more insight would be appriciated. Quote Link to comment Share on other sites More sharing options...
big-phil Posted April 2, 2006 Share Posted April 2, 2006 I was, and kinda' still am having trouble with this but I thought it was because I'm using a stock non adjustable eclipse bov. when I first put it in it sucked air just at idle, so I did what any good mechanic should do. I grabbed a big hammer and smacked the top of it to crush the spring down! It feels better but on the highway I think she is leaking. I also cut it off the stock 1.75 inch pipe and welded it to a 2.5 inch pipe. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted April 2, 2006 Share Posted April 2, 2006 I am not totally sure about what I am going to say because I have reached the bottom of my TALL gin and tonic. Anyhow, the two signal lines are looking for a pressure differential to pop open the BOV. At WOT, the two lines see the same pressure and the spring is the only force that can keep the valve shut. Under boost, at WOT both lines SHOULD see the same pressure so they cancel out. As the throttle plate closes, you begin to develop a pressure difference between the two lines. The front line still sees boost but the back line starts to see less boost and maybe vaccum. When the difference in pressure between the two lines produces a greater force than the spring, the BOV vents. Under very high boosts, and the resulting high flows, you may be getting a pressure drop across your WOT. In other words, the TB could be a restriction even at WOT. Are you running 60mm or larger? As I see it. If boost is getting to both hoses evenly, and that pressure is getting delivered to BOTH sides of the BOV plate, then it should NOT blow off at any pressure. Explained: the boost on the inside of the BOV is pushing it open and the boost from the two lines is pushing it closed with the same force. They cancel and the spring holds the valve shut. You could mess with restrictors in the signal lines to modify the rate of signal. That would delay action of the BOV but it's all experimental and probably counterproductive in your case. You could also try locating different places on the manifold to pick up the signal. Good night I'm going to sleep well tonight. Quote Link to comment Share on other sites More sharing options...
zguy36 Posted April 3, 2006 Author Share Posted April 3, 2006 These are all things that I have tried, with no avail. I have put bleeds in the signal lines, switched the line locations, changed spring tensions, but still no luck. Doesn't matter too much though, I am fighting other issues now. It seems as though OBX sells fuel pressure regulators with diaphrams that are not fuel safe. My diaphram swole up when exposed to fuel and ruptured within two minutes of installation. Quote Link to comment Share on other sites More sharing options...
nienberg.11 Posted April 4, 2006 Share Posted April 4, 2006 I am not totally sure about what I am going to say because I have reached the bottom of my TALL gin and tonic. You'e a very articulate drunk. Quote Link to comment Share on other sites More sharing options...
Turbo Meister Posted April 4, 2006 Share Posted April 4, 2006 I had a problem with my Greddy type R BOV. I called Greddy 3 times and spoke to 3 different techs with 3 different results. I tried tightening and loosening the spring adjustment-to no avail. There are 2 fittings on the valve. The one on the spring housing and one on the valve body. The first one is linked to the air box and is pressurized by the turbos above the carb. The latter is a vent. I was told to also pressurize this vent to quickly open the valve when the carb throttle blades shut. In this configuration the turbos produced max boost of 10 psi regardless of how loose or tight the valve was set. I decided to undo this vent and discovered that now the turbos got max boost of 17 psi. It appears that the valve would consistently leak any boost above 10 psi with the vent pressurized. I have also read several tech articles in magazines that criticized this BOV for leaking boost under various conditions. All this time I thought I just had a defective valve. I still don't understand why the spring adjustment does not appear to affect the valve operation. Hanns Quote Link to comment Share on other sites More sharing options...
zguy36 Posted April 4, 2006 Author Share Posted April 4, 2006 I can change the valve operation with the spring adjustment.... loose gives no boost with a little surge, tight gives more boost with lotso surge Quote Link to comment Share on other sites More sharing options...
Forrest Posted April 4, 2006 Share Posted April 4, 2006 Hanns is correct - just to reiterate - there are two ports on the BOV. One is for reference. The other is to assist opening the valve. It is not a reference and most of the installation instructions I have seen recommend leaving it open to the atmosphere. Check out some awesome pictures that illustrate what's going on: http://www.stealth316.com/2-greddy-bov-anatomy.htm Quote Link to comment Share on other sites More sharing options...
zguy36 Posted April 4, 2006 Author Share Posted April 4, 2006 I understand the purpose of both ports. The top one goes to the intake manifold after the throttle body, and the bottom one (some don't connect this) goes to a boost reference before the throttle body. I can also be left as a vent for the bottom side of the diaphram. Go back and re-read my post about the troubles I am having. Your problem was a torn diaphram, but everything inside of my valve seems to be in perfect order. Quote Link to comment Share on other sites More sharing options...
Forrest Posted April 4, 2006 Share Posted April 4, 2006 That's not my page. I just wanted to show the cool diagrams that illustrate the BOV (the guy spent a lot of time on it) and that the second port was not a reference or signal port (as I see people many calling it.) It uses boost pressure to help open the valve more quickly. I have never used it on my Type-S. From the other forums I have read when I was trying to adjust mine, it sounds like it has made it harder for other people to find the sweet spot. Mine is working just fine. But it did have a tiny pressure leak around the adjustment screw. I'm not sure it was ever a problem, but I sealed it with some RTV. Best of luck. Quote Link to comment Share on other sites More sharing options...
Roostmonkey Posted April 4, 2006 Share Posted April 4, 2006 Ive been having the same problem with a turboX BOV. I know its a low end unit so it didnt surprise me too much.I have a Tial BOV on order to replace it. Does anyone have any experiences with this BOV? Quote Link to comment Share on other sites More sharing options...
Nigel Posted April 5, 2006 Share Posted April 5, 2006 The Mitsubishi BOV has a "quick release" port, like that second port on the Type-S, built right into it. If you look at the botom of the BOV, you will see a small hole next to the valve hole. Boost pressure is fed to the lower side of the BOV diaphram through this hole to make the valve open quicker. This is why Mitsubishi BOV's will leak if you up the boost too much (and Type-S BOV's too apparently). Most people just crush these BOV's to increase the spring pressure, but a few people have modified the valve to allow this port to vent to atmosphere (or have it controlled by another valve). Here's a link to one such site: http://www.dsmtuners.com/forums/showthread.php?t=220909 FYI, the new Greddy Type-RS just has a small hole now to allow the lower side of the diaphram to vent to atmosphere, where the Type-S has an actual hose nipple. Nigel '73 240ZT Quote Link to comment Share on other sites More sharing options...
BLOZ UP Posted April 5, 2006 Share Posted April 5, 2006 Ive been having the same problem with a turboX BOV. I know its a low end unit so it didnt surprise me too much.I have a Tial BOV on order to replace it. Does anyone have any experiences with this BOV? The TiAL BOVs are sweet! I've dyno'd a few cars with them, running 20-25psi and never had a single problem. I used a TurboXS RFL Type H, and it was decent. I ran 10-20 psi with it and never had a leak--except... sometimes in 3rd gear, at just the right RPM and load (and throttle position), it would vent. Quote Link to comment Share on other sites More sharing options...
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