hmmm
I still run my stock recirc on my 06MR...
I just put in the Injen complete intake and hardpipe kit
i get a slight flutter but
it in no way affects performance
you barely hear it and dont even feel it
no biggie at 24 psi

 

Some people say the OEM BOV is good for 25PSI, some say up to 28PSI. I figure if you are on the OEM Turbo, the OEM BOV is best.

 

It has been my experience that if the BOV is set to VTA driveability will suffer significantly and you will have the on/off sensation. When backing off of part throttle you will get some flutter and the jerkiness and that's mostly because of the VTA, the MAF is metering an incorrect value because it is expecting the air to recirculate and it is not there which causes the rich condition between shifts. I had a crazy setup on my VW 1.8T and had all kinds of issues with the HKS unit as VTA. Once I switched back to the Forge recirculating unit it was a night and day difference in driveability. The HKS held more boost but the Forge was much smoother in terms of driveability.

 

Will do. Thanks in advance.

 

good deal!

ill try the recirc greddy if i dont like it then the tial, can always sell that, if not then the stocker will do

cheers!

 

What you need is the Leak Stop Kit from Dejon tools.

http://evo.dejonpowerhouse.com/

 

I believe there are several types of "jerky" beahviors that can happen with Evos. Unfortunately, I don't reall know how to solve all of them. They have often been referred to as turbo surging. This may be incorrect most of the time. See below.

When I had installed a Buschur Stage 2 plus deluxe FMIC (with proper tuning) on my Evo VIII, I had lots of light throttle fluttering no matter where I adjusted my Forge RS BOV. If I put the cheap plastic OEM valve back on, the fluttering went away. If I put a MR style OEM (metal) BOV the fluttering was was very pronounced and worse than with the Forge BOV. So, it did not stay on the car long. The problem with the OEM plastic diverter valve is that it would not hold boost past 21-22 PSI. At this time I lived in the land of 93-94 octane.

My RS BOV would flutter under WOT at track events. I wrote Mike at Forge about this and never got a satisfactory response. So, the RS valve has spent most of its time in my tool box. These nagging drivability problems after modifying my Evo VIII are the strongest reasons why I traded my Evo VIII in for my Evo IX.

With the IX I intended to be more conservative with my mods to avoid the fluttering/tuning issues. A few months ago I put all of my old Buscur stage 2 stuff on my Evo IX and got a street tune from Al. All of the light throttle fluttering was there just like my old Evo VIII. I had previously convinced myself that the fluttering issues were from the TME turbo that I had put on the Evo VIII. So, I was pretty irritated to see that the fluttering had nothing to do with that turbo. I adjusted the Forge RS BOV from full soft to full tight and everywhere in between and the partial throttle fluttering was always there. The adjustment simply changed the throttle angle at which it occured. This happens when the boost has not built to positive pressure. So the intake is still in a vaccuum reading. For those who have no had the pleasure of this type of fluttering, it mostly happens when you have accelerated to keep up with traffic on the freeway and you ease off the gas to not run over the car in front of you.

Getting back to the stage II Evo IX, because my wife was complaining of all the hissing and farting noise comming from the conical intake, I took it off leaving on the rubber MAF pipe and I put the OEM DV and OEM air box intake back on the car with no other changes. The partial throttle fluttering is essentially gone. I can commute for days without it happening. I have no idea why this is true. I asked Al about this but he never replied.

As for putting the Forge RS BOV back on. I tried this but it still flutters much worse than the OEM DV and it would still flutter from time to time at WOT. So, it is not being used. I have inspected this RS BOV several times. The piston moves smoothly and is well lubricated with plenty of the factory grease.

So, my take on all of this is that there is more than one cause of fluttering. Somehow the airflow upstream of the MAF on a car tuned for the conical element is involved. Otherwise the changing back to the OEM airbox would have had no helpful effect on the fluttering. Last week I put the conical filter back on and all of the low boost fluttering returned. This was the only change to the car. I am now running the OEM intake again.

The second type of fluttering which I have been unable to diagnose or cure is the WOT (both sound and feel) fluttering that occurs irregularly with my Forge RS BOV. I have observed the boost gauge during these flutters and not noticed any change or fluctuation. At the track you are either on the gas or off of it much of the time. When an excellent driver friend of mine drove the car at the track, this WOT flutter issue was his first comment. It was ahead of the accelleration and the handling on track tires. It is irksome. It is not affected by the RS BOV adjustments. It occurred on both the Evo VIII TME and the Evo IX stock turbo. Since I live in Tucson and run 91 octane the boost was never above 21 PSI.

Does this describe any other Evo owner's experiences?

 

Great info, I have a similar problem, Bushur stage 3 on a 2006 IX MR and I get low boost / partial throttle lift fluttering / bucking.

I wonder if the people who don't think this is a problem live in areas without hills? The bucking is particularly serious when going up steep hills in anything above 3rd gear - maybe the people who don't think this is an issue just live in areas of the country that are flat? Keeping the car boosting or lifting off the gas quickly solves the problem, but this can be tricky when following slow traffic.

I have tried a number of fixes, larger vacuum lines, different mounting positions, testing with a vacuum pump etc... I also considered the 'adding a boost controller nipple to my LICP' fix, but to test if this would have any effect I just disconnected my boost vacuum line so the BOV was the only thing connected to its original vacuum source and I got the same bucking / fluttering coming off partial boost (I just didn't use full boost during testing as the wastegate was disconnected). One thing that might be confusing people is reading their boost pressure incorrectly. I have a Greddy Profec boost controller and it's digital display is far more accurate than my autometer Bushur one (which is actually not as accurate as the stock IX version - it's just in an easier location to read). If the Greddy shows even 1psi positive boost and I let go of the throttle a bit (not more than -5-6psi) it will cause bucking.

When testing my stock metal IX BOV with a hand vacuum pump it's easy to see why this problem occurs, the valve opens at about -12 to -15psi as it should, but ANY vacuum makes the valve easier and easier to push open with a finger - I image if there is still positive boost in the intake tract and even a slight vacuum behind the throttle plate, the valve will be pushed open and close and cause fluttering. I think a heavier spring will help this (which unfortunately you cannot adjust on the sealed stock IX BOV), but it's still going to occur to some degree.

I was going to order the Forge Motorsport Type RS Valve Recirculating BOV to see if this helped me adjust the problem away, but your response makes me worried that it won't make any difference. The horsepowerfreaks web site lists two types of Forge BOV - one with a 25mm connector and one with a 34mm - which version did you have?

Andy.

 

What you need is the Leak Stop Kit from Dejon tools.

http://evo.dejonpowerhouse.com/

 

My forge vavle works great, I've learned to just clutch in after i build up boost and let off. You can't leave boost in the system and expect the motor not to jerk about when you let off the throttle.

 

Sure you can.

 

I have a Forge Evo 15 valve and it flutters like crazy and the car jerks real hard. I dont know why it does this when its recirculating

 

Ive tested the various springs/settings and no matter what I do, I have to clutch in. Partial throttle spooling and then letting off abruptly will always duplicate this condition for me, I am very interested to know how you fixed this so I can do the same,

thanks

 

Nice Ad for Dejon. Please re-read the thread, this has NOTHING to do with leaking air past the BOV at full boost. This is a problem with very low boost situations and fluttering. The Dejon fix only improves the 1G BOV in high boost situations. Air leaking past the BOV is not a big problem, it will get into the engine eventually anyway - this is only a problem if you don't recirculate (which is not a sensible thing to do anyway unless cool noises is more important to you than drivability).

Andy.

 

I have the dejon leak stop kit (installed by them) and I get the exact same fluttering that everyone is describing. Hills are a pain..