The Forge package insert suggests that the problem has been identified. Neither of my Evos (VIII & IX) had this problem before they were modified. My Buschur stage 2 fluttered quite a bit with a Forge RS DV valve but did not flutter at all when the OEM plastic DV was swapped back onto the car. Of course, it could not hold much boost with the plastic valve. For street and daily driver use, I much preferred the plastic valve. No amount of adjusting of the Forge RS DV would make this part throttle ("no boost" problem go away). The adjustments would affect the RPM or load where the flutter occurred but could not eliminate it.

The posted Forge DV package insert says that this is "normal". Well, it is not normal to the cars as delivered from Mitsubishi and the drive train strain can not be good. I am not implying the the Forge DV is in any defective because the MR DV also had this problem on my Evo VIII and my present Evo IX has the problem with the OEM DV. I would strongly suggert that there is something about a better flowing exhaust or a better flowing intake or both that "activated" this problem. I am leaning toward an intake side problem as Forge suggests. But I would ask this. Is there anyone out there with only exhaust modifications or that has activated this problem?

I have a MBC (set to 21 PSI) it might also be part of the problem.


So, another question is why could Mitsubishi eliminate this problem and the Evo and aftermarket community can not? If Forge has correctly identified the problem, then what is the fix? If we open the idle throttle valve setting will this help? Will a change in idle RPM help? Can this be eliminated with some electronic tuning solution? Since a large number of us have this problem we need to pull together and find a fix for it.

Let me add another observation. This fluttering is much more exagerated when I run a Buschur conical filter than when I use the OEM air box. Why would this be? The car was tuned with the Buschur conical filter but has better drivability (much reduced fluttering) with the OEM air box. The "simple solution" is to drive the car like the throttle is an on/off switch meaning that you pull of the gas very quickly and eliminate gradual lift adjustments to your speed. This works but is annoying to the driver and especially to their passengers.

We need some of the engineering gurus or tuning gurus to speak up here and help us the rest of us out. I have yet to see a well thought out fix proposed for this problem. So, how about a little help!

 

Because you can't hear it with the stock airbox in place - everything is suppressed, but the BOV behaves the same.

 

The reduced fluttering with the oEM air box is not assessed by the sound. It is assessed by the pulses through the engine of the car. This is not the difference in sound. With the OEM air box the lift throttle studder is 1-2 to two cycles. With the connical filter it is 3-5 cycles.

 

make sure the bov is in the right way,,