I have a stock forged bov, atleast i think i do. I bought the car used and Im not sure if its the stock one or the jdm one (its silver steel with a brass looking top). The car is a 2006 xi gsr. My question is whenever i have my foot on partial throttle when the turbo is spooling slightly but not at boost yet i can hear the bov fluttering. If i take my foot off the gas when i hear this the car almost stutters as the bov is trying to close. Could the spring in the bov be too loose or worn? I have an intake on my car along with a K&N cone filter that has been tuned. There is no real drivabilty issues except for the occasional studder while at partial throttle.
I am assuming people are going to say take off the intake but since i tuned for it id like to keep it on (it came with the car so it was free) and i like to have my car sound like a truck when it is spooling Thanks for anyone's help!

 

I'm 99% sure that you're describing the stock IX DV. With an open element intake, you're going to hear more noises than normal obviously. When I experimented with taking the airbox cover off, I heard the same noises. Completely normal. The stock DV makes a lot of strange sounds at partial throttle. If the car is bucking at all, may be due to the intake not being tuned.

 

I thought that too. And even when i didnt have the car tuned it was doing the same thing. The car bucks/stutters and i am in part throttle and i hear the bov fluttering. When i hear it i try to let off the gas and it will start to buck. If i hear the bov stuttering and i floor it to get into boost the car wont stutter when i let off the throttle. I guess it really could be the intake though, i had the stock one on for a while though and although i couldnt hear the bov anymore i could still feel the stuttering at times.

 

Well our cars are ultra sensitive in terms of driving. I have to be very gentle with the throttle for a smooth ride. If I let off the gas it does stutter a bit, but not to where it is a problem really. Ride is someone else's Evo and see how smooth they are compared to you. A little jerkiness is normal.

 

^ Good to know

 

That is normal you only hear it because the intake lets you hear things better. I notice it especialy when I am at partial throtle and too low in the revs for that gear. I hope this helps.

 

I think most Evos are touchy when letting off the gas. To avoid I just let totally off the throttle most of the time instead of just lifting a little bit. With pratice you get it down.

 

figured. But i was just making sure since none of my friends have an evo to compare it to. Thanks guys

 

i too have the same problem with my stock 9, i never felt this in my 8 i guess cause of the stronger dv ! it happens in low rpms when you press on the gas and it tries to build boost but cant "too low in rpms" then you let off the gas and it jerks like crazy.

 

think of your gas pedal like an on/off switch

either it's on (full boost)

or

it's off (no boost)

the stock diverter tends to hide the surging feeling a lot better than aftermarket solutions but anytime you are partial throttle you basically confuse the car and the air has to go somewhere

there are much better/more technical answer to this...try searching for boost flutter or something of that sort and see what you come up with

moral of the story...try not to go partial throttle when building boost as your diverter doesn't appreciate that

 

do you have a boost gauge. I had the same thing happen to me. My bov wasn't closing properly for a while, It was fluterring when i let off the throtle and i didn't realise anything was wrong until i got a boost gauge and saw i was only boosting about 15 psi, changed it and now it's back at 22

 

Yea i have a boost gauge. It reads boost fine i think its just bov flutter. thank though

 

Its not "bov flutter" its compressor surge.

Low loads, low boost, part throttle it can happen - thats all it is.


search:
https://www.evolutionm.net/forums/se...archid=7497851

 

i'm getting this same thing, i installed a 9 dv on my evo 8...but with the evo 8 plastic one this was never an issue, now whether on 2 - step, shiftin high or low boost, it makes that fluttering noise.