Strange sound, loss of boost, BOV or wastegate?
Jan 1, 2006, 09:24 PM
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Strange sound, loss of boost, BOV or wastegate?
I did a search and couldn't find anything specific or close enough to my situation.
I have fairly minimal mods (see sig) and most importantly to this thread, a stock BOV and wastegate actuator on my 05. I plan on upgrading both to Forge units shortly. Airbox is stock except for a Ralliart panel filter.
I've noticed recently that on occasion, I get a strange noise from under the hood at approximately 6K rpm. The noise sounds exactly like the air rushing in a car wash vacuum cleaner nozzle as you stick it against the carpet and there's still air flowing into the hose, right before you completely seal it against the floor. Airflow noise usually comes from a restriction. Now this does not occur at lower rpm and it'll do it in multiple gears, back to back, all at the same rpm point. I'll boost to 23psi, falling to 21 and then the gauge will drop to 16psi suddenly accompanied by the noise at the same time. It won't happen all the time but it seems to be happening with more frequency as of late, especially on warmer days but that may just be a coincidence. I'd think knock, but knock doesn't sound anything like this in my experience (being muffled?) I don't feel timing being pulled. I idle at 20" of vaccum and the car has a flash. I'd think it'd be more likely to knock at peak torque than at 6K.
My initial inclination is that it's the stock BOV being pushed open. I'm just surprised I'm able to hear it with the stock airbox. My second thought was the wastegate opening since it's happening in the upper rpm range and not peak boost at 3.5K, but it's inconsistent and therefore is most likely not the wategate opening.
It really does sound like something being opened and air forced out a restriction. I've checked the intercooler lines and they're all intact and tight, no leaks.
Anyway, I've done my best to describe it. If it is the BOV, I'm just very very surprised I can hear it given the fact I hear nothing when I shift and the BOV vents. I read a few posts about the BOV being on backwards but I have no surge noises coming from the turbo that I can hear. Thanks in advance for any information or help!
I have fairly minimal mods (see sig) and most importantly to this thread, a stock BOV and wastegate actuator on my 05. I plan on upgrading both to Forge units shortly. Airbox is stock except for a Ralliart panel filter.
I've noticed recently that on occasion, I get a strange noise from under the hood at approximately 6K rpm. The noise sounds exactly like the air rushing in a car wash vacuum cleaner nozzle as you stick it against the carpet and there's still air flowing into the hose, right before you completely seal it against the floor. Airflow noise usually comes from a restriction. Now this does not occur at lower rpm and it'll do it in multiple gears, back to back, all at the same rpm point. I'll boost to 23psi, falling to 21 and then the gauge will drop to 16psi suddenly accompanied by the noise at the same time. It won't happen all the time but it seems to be happening with more frequency as of late, especially on warmer days but that may just be a coincidence. I'd think knock, but knock doesn't sound anything like this in my experience (being muffled?) I don't feel timing being pulled. I idle at 20" of vaccum and the car has a flash. I'd think it'd be more likely to knock at peak torque than at 6K.
My initial inclination is that it's the stock BOV being pushed open. I'm just surprised I'm able to hear it with the stock airbox. My second thought was the wastegate opening since it's happening in the upper rpm range and not peak boost at 3.5K, but it's inconsistent and therefore is most likely not the wategate opening.
It really does sound like something being opened and air forced out a restriction. I've checked the intercooler lines and they're all intact and tight, no leaks.
Anyway, I've done my best to describe it. If it is the BOV, I'm just very very surprised I can hear it given the fact I hear nothing when I shift and the BOV vents. I read a few posts about the BOV being on backwards but I have no surge noises coming from the turbo that I can hear. Thanks in advance for any information or help!
Jan 1, 2006, 09:32 PM
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LOL, please don't tell me it's as simple as that...Would that really cause a significant drop in boost? I initially thought that might be where the sound is coming from but I couldn't explain the boost loss. I've managed to loose BOTH clips.
Jan 1, 2006, 09:37 PM
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Tomorrow before I go to work. I just got lazy when adjusting the MBC which is located, where else, UNDER the snorkel. PM me your paypal. 
Jan 1, 2006, 09:39 PM
#6
Bah!! Tomorrow?! If it were me, I'd be out there right now doing it and driving it all over the place in sheer bliss with the wondrous relief of knowing my cars wasn't f'd up!!!
Whackos, all of you!
Oh, and before you feel dumb because of this, take a second and wonder how I know exactly what you're problem is, haha...
Whackos, all of you!
Oh, and before you feel dumb because of this, take a second and wonder how I know exactly what you're problem is, haha...
Trending Topics
Jan 1, 2006, 09:54 PM
#8
For future reference, here's my calling card:
Bat-talon
My crew of saved Gotham City Residents:
someone help please
Boost Leak Sound
3rd gear..6k..no boost..loud vaccum noise
Weird boost problem, please help
boost control problems
Huge problem, please help!
help loud whisle
Bat-talon
My crew of saved Gotham City Residents:
someone help please
Boost Leak Sound
3rd gear..6k..no boost..loud vaccum noise
Weird boost problem, please help
boost control problems
Huge problem, please help!
help loud whisle
Jan 2, 2006, 05:28 AM
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Yeah I feel a bit stupid given my auto background/history. I knew there was nothing seriously wrong with the car, just thought it was strange and I knew there would be a reasonable fix. Given I have a limited amount of time with this car, I'm not familiar with all of it's quirks. I thought for sure the hood would at least be keeping the snorkel down somewhat (not!). But I was expecting to replace the stock BOV or the actuator at the very most.
I'm working on making cars a lesser part of my life than in the past. Six months ago I would have been out there fixing it. A year ago I would have "upgraded" to a stroker and big single. It's a 12 step program and I'm on the 2nd step, LOL. The first was buying a four door. Yeah. THAT was a bright move. I call the Evo my vain attempt at being somewhat responsible. If you saw my last daily driver, you'd understand. Oh and Warr, thanks for being so gentle
I'm working on making cars a lesser part of my life than in the past. Six months ago I would have been out there fixing it. A year ago I would have "upgraded" to a stroker and big single. It's a 12 step program and I'm on the 2nd step, LOL. The first was buying a four door. Yeah. THAT was a bright move. I call the Evo my vain attempt at being somewhat responsible. If you saw my last daily driver, you'd understand. Oh and Warr, thanks for being so gentle
Jan 2, 2006, 07:53 AM
#13
Well, did you fix it, and did it work?
When it happened to me, I spent a week trouble-shooting by doing numerous pressure tests, numerous uninstalling and re-installing of the MBC with complete re-tightening of every vaccuum hose and every IC pipe that I touched (or didn't touch). I switched out the BOV with a friend and then he finally asked me why I didn't have my snorkel fasteners in place. He didn't know that was the problem, but he was curious why I had it sitting loose. He then showed me how the stock fasteners were REUSABLE (I didn't know this), and then showed me where to find some spares (trunk), and next thing you know my car is back to normal.
Hey, Phenix, one of those threads was started by you, too, and I was nice!
When it happened to me, I spent a week trouble-shooting by doing numerous pressure tests, numerous uninstalling and re-installing of the MBC with complete re-tightening of every vaccuum hose and every IC pipe that I touched (or didn't touch). I switched out the BOV with a friend and then he finally asked me why I didn't have my snorkel fasteners in place. He didn't know that was the problem, but he was curious why I had it sitting loose. He then showed me how the stock fasteners were REUSABLE (I didn't know this), and then showed me where to find some spares (trunk), and next thing you know my car is back to normal.
Hey, Phenix, one of those threads was started by you, too, and I was nice!
Jan 2, 2006, 11:56 AM
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It worked as far as I can tell. It only did it periodically to begin with but I didn't have any issues going WOT to 7K in three gears this morning on the way in. I'm sure that was the problem at this point but if the strange noise returns, I'll post about it! I didn't go through all the trouble you did as I haven't touched most of the under hood components and it was easy to check them quickly. Plus I KNEW you'd chime in with the correct answer, LOL.
Aug 1, 2006, 08:14 AM
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Warrtalon for president!
Originally Posted by Warrtalon
Man, I love these threads.
Fasten your snorkel down with both clips.
Send payment for my consultation fee via Paypal.
Fasten your snorkel down with both clips.
Send payment for my consultation fee via Paypal.
Muchos Gracias!
Hmm?. I had the knowledge somewhere back in my head from back when the EVO7 came out, and yet didn't react when seeing the two clips on the snorkel was missing. Alzheimer?
Good thing though to pressure test everything. Found that the dump valve diafragma was leaking.
Mind if i send payment in virtual Zork Gold?
