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Discussion Starter · #1 ·
Hello everyone!

I'm new to this forum and i was hoping i could get some advice and maybe i could learn a thing or two while im here. To start with i have a;

2007 wrx wagon
2.5L dohc H4
current engine mods are;
Stage 1 cobb OTS tune
STI lower block
GFB blow off valve
catless downpipe and straight piped the rest of the way

I took Cobbs course for the AccessTuner software so I could tune my car on my own. after completion i used the software to make a burble tune simply by pulling the timing of the engine by -3 ish degrees, when the rpms are between 3500 and 1500 under load. This worked well on downshifts while decelerating. After installing the Blow off Valve from Go Fast Bits the burble tune stopped working unless the BOV was completely closed off. When the BOV is open and making the cool noise that it should my car no longer pops and bangs on decel. can anyone tell me why this is and possibly how I can correct it?

Thanks!

Clapped07'wrx
 

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Refit the proper recirculating valve, or turn that one to 100% recirculating. Remove the burble tune.

Problem solved.

It will remove all of the popping and banging from your exhaust the correct way instead of you happening across something that's probably even worse than the burble tune anyway.
 

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Discussion Starter · #3 ·
Refit the proper recirculating valve, or turn that one to 100% recirculating. Remove the burble tune.

Problem solved.

It will remove all of the popping and banging from your exhaust the correct way instead of you happening across something that's probably even worse than the burble tune anyway.
Okay I understand that is the correct way to fix it but say I wanted the car to backfire and make the blow off noise at the same time. How would one go about that?
 

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Okay I understand that is the correct way to fix it but say I wanted the car to backfire and make the blow off noise at the same time. How would one go about that?
By burning your intake valves up so the combustion gasses enter the intake and blow off the entire cold end with the backfire.

I can only tell you how to fix your car honestly and what you are asking for is entirely the opposite direction. You are asking advice on how to hasten the $10k engine replacement due to catastrophic piston failure.
 

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Discussion Starter · #5 ·
By burning your intake valves up so the combustion gasses enter the intake and blow off the entire cold end with the backfire.

I can only tell you how to fix your car honestly and what you are asking for is entirely the opposite direction. You are asking advice on how to hasten the $10k engine replacement due to catastrophic piston failure.
Okay fair enough I was just curious if it was possible for them to both run at the same time, unless I miss understood you said I should close of the BOV completely and run it shut?
 

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Subarus engine management strategy requires all air thats passed the mass air flow sensor to remain in the system. Its why they use a recirculating valve. The ecu expects that air to be there when accounting for fuel volume. Using a blow off valve sends that air outside of the system causing the engine to run super rich for a time after the throttle valve slaps shut and reopens. This rich environment causes carbon build up. My understanding is with modern vehicles and the egr its even worse for the buildup.

Carbon buildup can create an environment in the cylinder where the spark no longer controls the combustion preignition from hot spots do. This is how pistons go to hell.

The after fire you are talking about exaggerates this rich condition even further in hops combustion happens in the exhaust. Its not good for the turbo, or the exhaust and can blow out manifold gaskets leading to issues with leaks. This in turn messes with the turbos ability to spool, as well as stresses the bearings in it from the huge pressure spikes.

Your car is not a race car where its only got to survive a few hours before being torn down repaired and rebuilt. Set the car up properly and enjoy it.
 

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Discussion Starter · #7 ·
Subarus engine management strategy requires all air thats passed the mass air flow sensor to remain in the system. Its why they use a recirculating valve. The ecu expects that air to be there when accounting for fuel volume. Using a blow off valve sends that air outside of the system causing the engine to run super rich for a time after the throttle valve slaps shut and reopens. This rich environment causes carbon build up. My understanding is with modern vehicles and the egr its even worse for the buildup.

Carbon buildup can create an environment in the cylinder where the spark no longer controls the combustion preignition from hot spots do. This is how pistons go to hell.

The after fire you are talking about exaggerates this rich condition even further in hops combustion happens in the exhaust. Its not good for the turbo, or the exhaust and can blow out manifold gaskets leading to issues with leaks. This in turn messes with the turbos ability to spool, as well as stresses the bearings in it from the huge pressure spikes.

Your car is not a race car where its only got to survive a few hours before being torn down repaired and rebuilt. Set the car up properly and enjoy it.
So there is no safe way to run just the blow off valve? Because that thing wasn’t cheap and if I’m just gonna close it off then there is no point in having it yeah?
 

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So there is no safe way to run just the blow off valve? Because that thing wasn’t cheap and if I’m just gonna close it off then there is no point in having it yeah?
Yes, a quick research Google of 2 minutes would have shown you that burble tunes and blow off valves are not good.

There are shops out there that won't even humor working with your car if it has either because it's a problem waiting to happen.
 

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Discussion Starter · #9 ·
Yes, a quick research Google of 2 minutes would have shown you that burble tunes and blow off valves are not good.

There are shops out there that won't even humor working with your car if it has either because it's a problem waiting to happen.
Everything that found as far as research on the BoV said it was good for the turbo. I can understand the burble tune being a risky move. So I won’t tune the tune but as far as the BoV I’m still a little confused. I don’t want to waste your time, I’m here to learn from everyone for sure so your input is greatly appreciated.
 

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A relief valve is good. Specifically for subarus the recirculating valve.

If the Subaru ecu worked from speed density then it wouldn't matter. However they opted for an arguably more accurate system.

The only way a blow off valve could be better for your turbo is on a system where there is no type of relief valve available and it prevents the hammering of compressed air between the throttle plate and the compressor wheel.
 

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Not sure about how different it would be with your car but when I installed an intake I got way more turbo sounds. I can now hear the suction & pressure release. On both the axle back & cat back exhausts I have used there is a subtle crackle when downshifting. It's no burble tune but it's fun yet not obnoxious.

I have a 16 sti & I'm not very familiar with the 07 wrx so I'm not sure if those sounds would stand out the same for you but it's probably less likely to be destructive.
 
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