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View Full Version : BOV flutter, compressor surge?


Limeyboy
02-20-2006, 06:25 PM
My BOV (its stock) sounds like it 'flutters' (think "ps...ssh...ssh...shhhhht") when im shifting with high rpm. Its done this since I bought the thing.

If im at full boost, and let off the throttle quick, when the boost passes 0 and heads towards vaccum, the engine splutters like its just crapped out, then kicks back into life, almost like it died for a split second... This is annoying to say the least, and pisses me off on the freeway. If i dont go over about 5 psi boost, the problem doesnt happen.

Oh yeah, and at full chat, my boost seems to go up to 20psi or so, then drop off to a steady 18 after a second or so...

So, from what I have read on froums, its likely my BOV is sticky and im getting 'compressor surge' - am I right? If so, do I need to take this back to the dealer, or can I just adjust the stock BOV myself? Am I actually seeing a combination of factoring problems, or have I hit the nail on the head?

Thanks for the advice as always

:bow:
earlyapex
02-20-2006, 06:29 PM
Your stock BOV does this?

You sure you don't have it hooked up backwards?

Do you have it piped back into the intake like stock?
Limeyboy
02-20-2006, 06:33 PM
Your stock BOV does this?

You sure you don't have it hooked up backwards?

Do you have it piped back into the intake like stock?

Yes - stock indeed. I havent modded the engine in any way. Infact, the dealership put a brand new engine in so they could sell it with a warranty (old engine was modded). Hmm, i wonder if the BOV is not stock, and they recylced it.. though, it looks black and plastic to me, with all the hoses looking like they are in the right place :(
earlyapex
02-20-2006, 06:36 PM
Make sure its hooked up correctly:

http://www.norcalmotorsports.org/users/bryan/mods/EVO/stock_bov/stock_bov_installed.jpg

http://www.norcalmotorsports.org/users/bryan/mods/EVO/stock_bov/stock_bov_loose.jpg
Matz
02-20-2006, 06:43 PM
Oh yeah, and at full chat, my boost seems to go up to 20psi or so, then drop off to a steady 18 after a second or so...

Boost taper is normal, unless you have a reflash like Dynoflash, WORKS P2, or additional hardware like a MBC / EBC. Or are you including that information to tell us that under WOT, your boost levels seem normal? :oops:
EvoRicer
02-20-2006, 06:47 PM
Oh yeah, and at full chat, my boost seems to go up to 20psi or so, then drop off to a steady 18 after a second or so...

Boost taper is normal, unless you have a reflash like Dynoflash, WORKS P2, or additional hardware like a MBC / EBC. Or are you including that information to tell us that under WOT, your boost levels seem normal? :oops:


Even with MBC or EBC...Boost Still Tapers a little from all the other threads I read on EvoM and stuff.
Limeyboy
02-20-2006, 06:52 PM
EarlyApex,

Well, that is the BOV thats in there, but the thing is definately not hooked up like the picture. The one in your pic is horizontal, but in my engine bay, its vertical.

This makes me think one of two things:

-Capitol mitsu engineers are dorks and put it in the wrong way round.
-Its possible some were made to fit vertically (surely i wouldnt hear any blow off, and my boost guage would be screwed if it was fitted the wrong way round? My boost gague taps into the the small line heading to the intake manifold, and it shows correct boost/vaccum)

Thanks for the pic and help! Makes a bit more sense!!
Limeyboy
02-20-2006, 06:53 PM
@ Evoricer/Matz - thanks for the info. Im not worried about that at all in which case :)
earlyapex
02-20-2006, 07:00 PM
EarlyApex,

Well, that is the BOV thats in there, but the thing is definately not hooked up like the picture. The one in your pic is horizontal, but in my engine bay, its vertical.

Then yours was installed wrong and can cause damage to the turbocharger, flip it around. That is the reason for your problems.
Limeyboy
02-20-2006, 07:05 PM
Then yours was installed wrong and can cause damage to the turbocharger, flip it around. That is the reason for your problems.

Thanks very much! So now im concerend as I have driven it for nearly 1700 miles with it the wrong way round. So, what I imagine is happening is that the air is being forced back down into the turbocharger and could cause bearing damage?

My main question would now be, do i take it back to the dealer and have them replace the turbo and BOV under warranty as its their liability, or do I just flip it round myself and hope the turbo is fine. I mean, it certainly feels responsive enough - is there anything I can do besides taking the turbo off and feeling for give on the bearing?
earlyapex
02-20-2006, 07:12 PM
I doubt it's done any damage. If you have the time, take it to the dealer if you want to be careful about it, or just flip it around yourself.

The problem when its flipped around ,is that it isn't venting the pressure back into the intake tube as well as it should so you are getting a bit of compressor surge (which is the pressure being force back into the compressor outlet).

You can check the turbo for any shaft play by wiggling on the compressor wheel side to side, some little movement is normal, but it should not move more than that. To do that , you have to take off the intake snorkal. And don't do it when the engine is running of course. :D
Limeyboy
02-20-2006, 07:13 PM
Thank you for all the help EarlyApex . :urock:
earlyapex
02-20-2006, 07:14 PM
No problem, I hope it solves your problems.
Limeyboy
02-21-2006, 01:12 PM
problems solved!!!
MitsuMan
02-22-2006, 01:21 AM
dude you should of mentioned this at the HIN show I could of drove with you in the car and checked it out . can't really say what it could be without driving the car and seeing for my self
Matz
02-22-2006, 07:48 AM
dude you should of mentioned this at the HIN show I could of drove with you in the car and checked it out . can't really say what it could be without driving the car and seeing for my self



problems solved!!!


:thumbsup: He's good to go! I'm glad to hear that everything is normal with your Evo now!
Limeyboy
02-22-2006, 10:46 AM
dude you should of mentioned this at the HIN show I could of drove with you in the car and checked it out . can't really say what it could be without driving the car and seeing for my self

No worries :) I meantioned it to coruja, who said to ask you, but it completely slipped my mind. Now just to work on getting the MPG up a bit.. its running 180 miles a tank :(
earlyapex
02-22-2006, 11:11 AM
dude you should of mentioned this at the HIN show I could of drove with you in the car and checked it out . can't really say what it could be without driving the car and seeing for my self

Once again, if you read the whole thread you would have realized the problem was solved a whole day before you posted. Why do you keep doing that?