Hi, i have a question about my WRX it maybe a dumb question but i'm not as familiar with Turbo's as i should be. I have had my WRX since 2003 and havn't done any modifications, i was waiting for my warranty to be up, and now that it is i put a few things on. I recently added an Agency Power BOV and a few days later installed an AEM Cold Air intake. Ever since i installed the intake the turbo (or somehting under the hood) makes a weird sound when letting off the throttle. It is heard the loudest in third gear doing 40 MPH at about 3,000 RPM. It almost sounds like metal grinding on metal, but you only hear it for a split second. It sounds like a... tick... tic... tick.. tick very breifly. If someone could help me out and let me know what this is and if it's a bad or not. I think it sounds like the turbo fins rubbing on the housing but it doesn't make sense cause all i did was install a BOV and Cold Air Intake. Sorry for the Dumb or Noobish question as some of you may say but it concerns me just a little. Any help would be appreciated, thanks.

Hi, i have a question about my WRX it maybe a dumb question but i'm not as familiar with Turbo's as i should be. I have had my WRX since 2003 and havn't done any modifications, i was waiting for my warranty to be up, and now that it is i put a few things on. I recently added an Agency Power BOV and a few days later installed an AEM Cold Air intake. Ever since i installed the intake the turbo (or somehting under the hood) makes a weird sound when letting off the throttle. It is heard the loudest in third gear doing 40 MPH at about 3,000 RPM. It almost sounds like metal grinding on metal, but you only hear it for a split second. It sounds like a... tick... tic... tick.. tick very breifly. If someone could help me out and let me know what this is and if it's a bad or not. I think it sounds like the turbo fins rubbing on the housing but it doesn't make sense cause all i did was install a BOV and Cold Air Intake. Sorry for the Dumb or Noobish question as some of you may say but it concerns me just a little. Any help would be appreciated, thanks.

You installed the two least important mods on your subaru, man. Check out COBBTuning (http://www.cobbtuning.com) and look up the stage 2 power package. That's all you really need for basic street performance. The intake has negative effects on the MAF sensor and the BOV is just pointless unless you like the noise.

I don't think that noise is what you think it is. Get under the hood with the engine running and have it revved a few times to pinpoint the location. It might just be what you installed.

Hi, i have a question about my WRX it maybe a dumb question but i'm not as familiar with Turbo's as i should be. I have had my WRX since 2003 and havn't done any modifications, i was waiting for my warranty to be up, and now that it is i put a few things on. I recently added an Agency Power BOV and a few days later installed an AEM Cold Air intake. Ever since i installed the intake the turbo (or somehting under the hood) makes a weird sound when letting off the throttle. It is heard the loudest in third gear doing 40 MPH at about 3,000 RPM. It almost sounds like metal grinding on metal, but you only hear it for a split second. It sounds like a... tick... tic... tick.. tick very breifly. If someone could help me out and let me know what this is and if it's a bad or not. I think it sounds like the turbo fins rubbing on the housing but it doesn't make sense cause all i did was install a BOV and Cold Air Intake. Sorry for the Dumb or Noobish question as some of you may say but it concerns me just a little. Any help would be appreciated, thanks.


Those mods shouldn't really affect the turbo. the BOV only causes a short rich condition in the engine each time, and the CAI just adds well..cooler air into the turbo to force into the engine. However, metal clanking is never a good sign! You could just have turbo which has gone bad. The only moving parts are the fins of the turbine/comrpessor, and the wastegate. One of those is hitting something. Check to see if your wastegate is stuck open. Are you losing boost? Is there a boost gauge in your car, and if so is it boosting normally? In any case, I think the turbo may be going bad. If you do decide to replace and don't have the desire to get a lot bigger, get yourself a regular 16g from deadbolt :)

Try looking at this post: http://carforums.net/showthread.php?p=77978#post77978

I don't want to scare you, so take everything that it says with a grain of salt because I am not sure about the whole think but some of it makes sense but I dunno what is true. But it may help you out a bit.

Thank you for taking your time to reply to my post. UberCivic the big upgrades for my car will come later on like thos on COBBTuning $1715. For right now a cold air intake and BOV are good. For $400 Dollars you cant go wrong. 03flat04, the noise was never heard until the CAI was installed. I do have a boost gauge and everything is boosting normal. Later down the road i will replace the turbo with a bigger one.
As for the noise, it is not heard at idle when revving, only when there is a load on it. So i can be 100% positive that it's coming from the turbo but i'm pretty sure. The BOV i have is adjustable to 100% atmospheric or 50/50. It makes the same noise when i set it to both of those or all the way closed witch inturn is supposed to be like having the stock BOV (bypass valve). I'm am still trying to Diagnose the S**t out of this problem and not getting anywhere, i just hope that my fins arn't getting destroyed in the Turbo. I have been told that my turbo fins could possibly be floating due to the backpressure caused by the BOV but i dont know. I would like more input from you guys on your ideas, thank you.

cant* be 100% positive i mean, sorry.

Ah, if you're only hearing the noise when the boost is moving in a positive direction, that has got to be the turbine or compressor wheel hitting the housing, or what would seem to be like shaft play, that is, the shaft that the wheels are attached to is no longer stable and somewhat free floating causing the wheels to hit the housing. Not good. The unfortunate thing about IHI turbos is, that they cannot be rebuilt. imho, the turbo is on it's way out. But it should fall under warranty for powertrain. Remember to just not get an IHI turbo when you upgrade. they are the suq!!!

Sorry, i didn't write my last post right... ment to say i dont hear the noise when it's idleing but i do hear it when i let off the gas after being at about 4,000 RPM. It's the loudest in 3rd gear.

Do you hear it from 4k rpms all the way to redline? Try to get under the hood and find a general area where the noise is coming from.

No i dont hear the noise when i'm on the throttle, only when i let off, it's a very breif noise. So when i'm driving 40MPH in 3rd gear at 4,000 RPM and i let off the throttle.. thats when i hear the noise for a split second. Sorry about the description i'm trying to describe it as best as possible.

I have been reading forums all morning and found that many people are having the same problem i have and they are calling in Wastegate Flutter. They asy to turn the wastegate actuator in 3 turns and it cures the problem, i want to read more on this though before i go messing with that actuator.

I have been reading forums all morning and found that many people are having the same problem i have and they are calling in Wastegate Flutter. They asy to turn the wastegate actuator in 3 turns and it cures the problem, i want to read more on this though before i go messing with that actuator.


Sounds like a good idea, make sure you know the consequences and how it will actually cure the problem before you mess with anything ;)


Good luck and keep us posted

well havn't messed with it yet but read into it even more... now i dont know if it's compressor surge or wastegate flutter. Could i get a little information on compressor surge please, cause i'm not to sure of what it is.

Ok, i finally called Agency Power and they said that the little flutter noise is normal but you shouldn't hear it that often, he said to back the adjuster all the way off and turn it in 4 turns and that should set everythgn right and i will only hear it at the end of 3rd gear but quietly. He said the noise i'm hearing is the little piston in the BOV going back and forth very fast for a breif moment. I guess almost all BOV's do this because i also called the company that i bought it from and they had a few ppl come in and try 4 different BOV's and they all did the same thing. Thanks for everyone's help though.

do you have a boost gauge? I wouldn't even come close to touching that wastegate without a boost gauge, and you should seriously get rid of that intake, you are doing nothing but making your engine run lean and you're gonna wish you put it on while you still had a warrenty on your car rather than after