Over boosting and recirculation

T

The_big_dill

Hey all,

So my buddy recently got his MSP, runs like a clock, 180 PSI in all 4 cylinders.

But we had a bit of a concern...

Every time you let off the gas, you hear the turbo fighting those boost pressures (the turkey sound). I haven't heard it this loud on these cars before, but I also never heard another MSP in person, just from videos.

In any case, am I looking at a failed recirculation valve or something??

Furthermore, he just got it from the body shop and the boost gauge shows that he is pushing 10PSI now, it use to be 6PSI. Is the wastegate/actuator acting up or what?
 
either the wastegate actuator is blown, or you may have a vac leak somewhere. either way something is definitely acting funky, I wouldn't want it boosting that high untuned.
 
The turkey is typically the result of a cold air intake, it is also present in stock form but the stock airbox muffles the sound. I have never heard of the turkey sound being caused by a faulty WGA in my 12 years of ownership.

Im assuming the car has a CAI?
 
Good assumption, it does have a CAI. So the car is designed to be able to take the boost pressures?

I was just worried because its hard on the turbo. Any way I can test the bpv?
 
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So is there anything besides the WGA that can cause the spike in boost?

It use to be at max 6PSI according to the boost gauge. Then after the body shop, it started going up to 10PSI, and it sounds like the turbo is working harder than before.
 
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To test the bypass valve you'll need to pressurize it to ~7psi and see if it opens. Im not sure how else but there could be other ways.


Boost spike can be dependent on many factors, such as type of WGA (stock vs ATP vs Forge Vs faulty WGA), ambient temperature, gear, exhaust size, leaks in the plumbing......

If its a stock WGA chances are its gone bad, test by blowing into it (might want to get your GF to do this as to save some pride haha) and if you can pass air through it chances are its faulty.


I would first check the WGA, and check for any leaks in the turbo plumbing, especially on the exhaust side.
 
The_big_dill said:
Good assumption, it does have a CAI. So the car is designed to be able to take the boost pressures?

I was just worried because its hard on the turbo. Any way I can test the bpv?
Click to expand...

You are assuming the 'turkey' is compressor surge however it is normal and honestly even if you upgrade to a larger BOV and external WGA there is nothing you can do to eliminate it completely. Not to mention even if it were compressor surge and it was doing damage the BB turbo in the msp would handle it anyway. You can test a BPV or WGA with a vac pump/tester.
 
Thanks for the replies guys.

I am not trying to get rid of the turkey, I prefer it to the bov. I was just concerned about damage to the turbo.

We drove the nuts off it today and the Max it hit was like 7.5 PSI which is good news. But with people in the back, the exhaust skins the front on every bump.
 
Hmm, the rear struts must be worn out. My car will scrape over bumps when I have people in the rear, stock height but wider offset rims. Once he has a few mods (FMIC, BOV, exhaust, tune, mounts) it will be a COMPLETELY different car.
 
to get out of a stock msp and hop into one thats been modded its a world of difference.
 
So the thing is over-boosting again... 10PSI and it feels like there is a really aggressive power cut.

I want to say its the wastegate actuator, but would it be doing this? If it was sticking, wouldn't it be a problem in the open position?
 
Check all your vacuum lines. If it has a leak to the wga and bpv it could cause some really bad issues.
 
Actually, the connection between the intake manifold and the WGA looks like its been patched together with pieces of intake tubing... its got 2 plastic fittings, 1 of which is a 3 way branch with a bolt zip ties to plug it... LOL

We will try replacing it and see what happens.

Also, the PRC solenoid valve is not connected to anything... the vacuum hose has just been cut.
 
It probably is hitting fuel cut, the internal flap for the waste gate could be hitting the side of the housing and getting stuck but that typically causes low boost and the flap sticks open. Pull the vac line to the WGA and blow into it, if it passes air the diaphragm is bad and it needs to be replaced.
 
So we blew through the WGA vacuum line and there is quite a bit of resistance, but as I increase pressure, i feel more air going through the WGA.
 
this is probably the problem. a Leaky hose to the waste gate actuator will act like a bleed type boost controller (they do the same thing). while you are fixing this hose try to pressurize the waste gate actuator line somehow. you should be able to feel it open with your hand (just make sure the engine is cool). if you don't have a pump of some kind you can try to blow through it with your mouth. if you can actually do it then the diaphragm is completely wasted and you are over boosting. replace the waste gate actuator.
 
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