BOV Always Fluttering...Multiple BOV's....

[ChitownDSM]

Hey guys. I just installed a few upgrades to my ride including a new turbo and IC piping. Anyways after getting the car all set up and ready to rock and after a healthy tune I noticed a lot of fluttering coming from my BOV. Now the BOV at the time was a Turbo XS RFL. I was getting sick of the noise from this BOV anyways so I bought a brand new Greddy Type-RS bov and installed that on a modified 1g flange. I boost leak tested and everything but I can;t figure out what is causing this flutter out of my bov. It only happens when I am between 0-12psi. After 12psi it seems to open let off and then flutter a little bit more then close. I loosened this screw at the top all the way until it almost came out of the BOV. It's about as soft as it goes but I still get this fluttering. I have my MBC and WG and BOV all on the t fitting set up. Please someone let me know what I can do to make my BOV open let off the boost and then close without fluttering.

 

[mitsugst97]

Hey guys. I just installed a few upgrades to my ride including a new turbo and IC piping. Anyways after getting the car all set up and ready to rock and after a healthy tune I noticed a lot of fluttering coming from my BOV. Now the BOV at the time was a Turbo XS RFL. I was getting sick of the noise from this BOV anyways so I bought a brand new Greddy Type-RS bov and installed that on a modified 1g flange. I boost leak tested and everything but I can;t figure out what is causing this flutter out of my bov. It only happens when I am between 0-12psi. After 12psi it seems to open let off and then flutter a little bit more then close. I loosened this screw at the top all the way until it almost came out of the BOV. It's about as soft as it goes but I still get this fluttering. I have my MBC and WG and BOV all on the t fitting set up. Please someone let me know what I can do to make my BOV open let off the boost and then close without fluttering.

try not tapping anything into the BOV vacum line. instead use the J-pipe or a different vacume source for the other things like MBC and wastegate..
That should help out some.

 

[MrBoxx]

I agree with mitsugst97. Tapping the BOV line is likely creating a boost leak, which may be opening your BOV prematurely. Use the compressor housing or intercooler pipe nipple for a boost source for the MBC.

 

[hottboost]

Let me give you good advice. Although it may contribute to your problem you always want your mbc tee'd in as close as possible to the manifold. that is the boost preasure you want to control. the reading your mbc gets from the compressor housing may be different and will make it harder to control boost as it can vary. Although I do agree it could be part of the problem

 

[MrBoxx]

Taking the pressure source from the j-pipe fitting has many benefits.

1. The main reason why alot of mbc instructions and some tech articles suggests to tap from the BOV line is because it's connected to the intake manifold, the argument is that this is more accurate because it's the same pressure the engine sees. In reality this is a non issue because the boost gauge is tap to the intake manifold no matter where you tap your mbc so there is no advantage in tapping the bov/manifold pressure as previously thought.

2. The proper functioning (opening and closing) of the bov depends greatly on the accuracy of the pressure in the vacuum hose you're thinking of tapping on or off boost so it's best to leave it connected directly to the manifold without any interference.

3. Tapping off the compressor/j-pipe offers the shortest vacuum hose route which greatly reduces the chance of boost spike.

4. In the case of boost leaks, tapping off the compressor/j-pipe will help prevent over boosting the turbo.

5. Hooking up a bleeder type mbc like the TurboXS standard mbc to the bov line will result in a vacuum leak as well as affect the working of the BOV.

-as originally posted by oldman

I have my MBC boost source coming from the lower intercooler pipe. Over the course of three years of rain, sleet, snow, cold Michigan winters (below 0*F) and hot Michigan summers (over 100*F) my boost has remained constant and rock solid.

Plenty of people have reported that changing from the BOV line to a direct boost source solved all of their overboosting, boost spike, and BOV problems.

 

[No_Skillz]

ChitownDSM - is your BOV fluttering while your are boosting or after you let off the gas?

 

[hottboost]

See for me it was the exact difference. I had mine to the compressor housing and it was set at 17psi, it would spike to 19psi and at low revs would climb to fuel cut. Tee'd it to the bov and its been fine. set at 18psi and may spike to 19 for a sec then calm right back down. But i have heard this both ways.

 

[zippyshoe]

When I first installed my Greddy Type S, I also experienced fluttering even with the BOV set fully soft. I performed the "single-spring" mod on my Type S and the fluttering was eliminated. I am not that familiar with the internals of the Type RS, but I believe the Type RS and Type S are similar in construction. Here is a link which explains the "single-spring" mod: http://www.evomoto.com/tech_info.php?tPath=1&tech_id=7

I agree with MrBoxx that, for overall best results, use a direct boost source for your MBC.

 

[TSIMonsteR]

so fluttering is bad ?

 

[ericbev]

so fluttering is bad ?

What is compressor surge?

Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall. In cases of extreme surge, the thrust bearings of the turbo can be destroyed, and will sometimes even lead to mechanical failure of the compressor wheel itself. It is commonly described as a chuffing or fluttering sound depending on the severity. You will know it when you hear it.

 

[zippyshoe]

so fluttering is bad ?

Yes. "Fluttering" is a sound that is actually produced by your turbo - NOT by the BOV. This sound indicates that your BOV is not opening to release the pressurized air. Since the pressurized air can no longer escape through the BOV, the pressurized air escapes back through the compressor-side of the turbo. The fluttering sound is what you hear when this air attempts to pass through the blades of the compressor. This is hard on your turbo, especially over a long period of time.

EDIT: Whoops. Beat me to it, ericbev.

 

[kawboy]

Fluttering develops into shaft play on your turbo.

Try running your MBC directly off your compressor housing or J-Pipe (If you already haven't)

Also, the Turbo XS RFL is a heavy duty BOV made for big turbos and high boost. Maybe it's not the right turbo for your setup? A good rule of thumb to go by is never buy a turbo based on its sound.

 

[jccjr1982]

Yes. "Fluttering" is a sound that is actually produced by your turbo - NOT by the BOV.

Actually fluttering can be produced by the BOV too.

I can "catch" my BOV fluttering. When I adjust my BOV to a soft setting, and rev the engine from the throttle body cable, I can see and hear my BOV fluttering.

 

[Dream On]

When I used RTV for a BOV gasket, some of it covered the small hole on the bottom of the BOV. It clogged it up and caused it to flutter. In the event that you used RTV for the gasket, I'd check that also.