Ok so I know there's a name for whatever is happeneing, but when I accelerate and let of the gas partially I hear a fluttering noise from the DV or turbo I assume.

Is this compressor surge? On a factory turbo?

 

Sounds like it

 

I wonder why this is happening with the factory turbo/DV. I don't think it happens at WOT though.

Any ideas?

Check my sig for mods.

 

Just depends how low the rpms are and how much gas your giving it if your part throttling in low rpm's then it's fine but if your wot then it's bad possibly it's leaking how much boost are you running....

 

Mine flutters like crazy in low rpm's sound like space invaders....

 

Running 25 PSI. Tuned my TTP.

 

Sounds like compressor surge to me.

 

Ok so what can I do to fix it?

 

i had the fluttering problem before. the thing drove me crazy! dont know where it came from but i know it was after my AEM and tune. so i keep thinking its my AEM. took everything apart and made sure its tight and not loose. I also had a 2nd tune and after that it went away. im starting to think it started with the tune, if thats even possible.

 

My stock turbo did this as well, just avoid spooling 5 psi at under 3000 rpms if you are going to let off to part throttle often. Likely if you let off the gas completely it won't try and force that boost through the engine and the BOV will just vent it. Trouble is if you partially close the throttle the engine is using very little air and the compressor wants to force more in but it backs up and makes that surge sound.

For the most part in low boost conditions it's probably harmless but with larger turbos you can get that at WOT by spooling too fast with a large compressor wheel. If the engine can't flow all that sudden volume of airflow you get some Compressor surge. Anything that reduces the engine's ability to breathe will make it worse such as high altitudes.

I'm getting some with my GT3076R turbo and it has an anti-surge ported compressor housing! Between the ball bearing center section, twin scroll, wrapped headers, and wrapped turbo it appears that I'm just trying to spool such a large compressor wheel too quickly for the engine to digest. So far I only get the WOT surge in 5th gear at 3600-4000 RPM's but I've heard that the FP Red and Dom 2 can experience it as well if building too much boost at to low an RPM.

I've read that possibly cams or an upgraded Intake manifold would help reduce WOT surge but for part throttle surge I would just change your driving style. I'm unsure if tuning the MIVEC would make it better or worse so I'll likely have to test this myself. Getting a BOV that is more sensitive may also help, although with greater sensitivity you usually lose some ability to hold higher boost levels so it's a balance.

 

This "part throttle letting off to part throttle" surge you're getting is normal for any turbo car and pretty much harmless. Basically the turbo is pushing air at part throttle and when you let off to a lesser part throttle, there's not enough vacuum/pressure difference in the intake manifold to open the BOV, so the BOV doesn't open and you get that light surge that you're hearing. It doesn't just happen randomly as it's very repeatable. I don't worry about it

Unless it's a HKS SSQV - very responsive and the more boost you run, the more the valve stays closed.

 

i swear we need a sticky on the difference between wastegate flutter and compressor surge. this has been covered so many times it's becoming boring.

 

+1, great post, on a side note, most of the time the fluttering noise is either the waste gate or BOV, it all depends on what kind of spring your running in it as well.

 

You are not getting compressor surge. Unless you have your DV mounted backwards.

What you are hearing is called "flutter dump". It has to do with your stock dv. Rather than actuate correctly and open completely and on time, it is slightly delayed making a flutter sound before it completely dumps the air into your intake tube. This is commonly confused with compressor surge. If you want to elliminate this, get a pull type bov or dv like synapse engineering or HKS SSQ. Do a search on it. I think on streetfire.net there is a video by Synapse demonstrating it. Search there.

 

^^ I agree sounds like a compressor surge.. you may have something hooked up wrong. The car isn't suppose to make that sound. It happend to me once, I took my car in for service and the num nuts at the stealership hooked something up wrong. I don't think that's good for the turbo friend..I'd try and get that fixed ASAP. Good luck!!