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Discussion Starter · #1 ·
Hey everyone 2015 Forte5 stick shift with a CAI, turboxs BOV, tork pipe, cat-back exhaust, and OCC. Had the car for about 5,000 miles now (close to 57k miles) and the other day I gave it a good stomping on the backroads coming home from work. Tight turns and steep hills, very hard to hit much higher than 50mph but a lot of up and down shifting. About two minutes into my beating I noticed the turbo making that fluttering sound that echoes out of the intake pipe every time I let off to shift. I have only heard this sound once before when I had to move the car when it was ice cold, and it only did it when letting off the throttle/shifting as I moved the car about 50 feet.

Now I continued the abuse and finished my hard ride for a few miles back to the main road. Once I got on the main road I resumed normal driving and to my surprise, the flutter went away after I got back up to sixth and went about my ride home. The first time it fluttered I made sure there was no CEL, I wasn't overheating, and nothing was abnormal as far as performance went. It pulled hard, spooled quick as it always does, and didn't lack power.

I have read that that sound is compressor surge and that it is not good for the turbo. Is that the case? And why would it only do it after a few minutes of shit stomping? Maybe the BOV is wearing out? Any ideas?

Thanks
 

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Are you sure it was flutter and not BOV actually venting?

I would suspect BOV venting as you got a bit too hot and ECU wanted to limit boost...
Unless your BOV is malfunctioning.
 

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Maybe pull the BOV off and give it a good cleaning? How many miles are on it? There might be some gunk inhibiting free movement. Also, perhaps the MAC solenoid is malfunctioning?
 

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I wonder if that intermittent issue is why the last owner sold the vehicle...
I'm clueless when it comes to mechanical issues so I use a scan tool to diagnose problems. I don't know if their functionality can pinpoint your issue due to the mods.
 

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Discussion Starter · #5 ·
Thanks for the tips. It got pretty cold up here in CT last week and I noticed the same issue happen again when running errands. It was about -5 outside and I heard flutter almost every shift all day. A buddy of mine said the same thing about maybe gunk in the valve which was causing it to stick shut in cold temps. I'll try taking it out and cleaning it.

Also I'm going to try and bypass the BOV solenoid and see if I still get the same issue. Car has about 57k on it so who knows how long that valve has been on there.

There is a capped off tee on a vacuum hose off of my throttle body, which makes me think someone had the solenoid bypassed in the past. I figured they probably reverted it to stop tripping the check engine light that I have heard sets every so often when you bypass the solenoid.

Will remove the valve and let everyone know what happens. Thanks.
 

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There is a capped off tee on a vacuum hose off of my throttle body, which makes me think someone had the solenoid bypassed in the past. I figured they probably reverted it to stop tripping the check engine light that I have heard sets every so often when you bypass the solenoid.
Not necessarily.
It could have been a tee for boost/vacuum gauge.
Good luck with your test and let us know what you found.

On a side note - I think that maybe the cold air is so dense that ECU limits the boost as it already produces all power requested...
 
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