Okay for Starters its a 2008 evo gsr 38k miles, only mod is ETS cold air. So I first noticed it when I was cruising on the highway and the speed limit change from 45 to 55. I stayed in 5th and proceeded to get up to 55 and while I was accelerating the turbo begin the spool and you can hear the loud sucking/vacuum noise and it was building good boost and then all of a sudden it started to make a fluttering noise. It doesn't always do it but a lot still. Also I'm not getting full boost when I go WOT but as said earlier, sometimes I get full and others I don't. Help!!!

 

mine does that occasionally too. usually when I accelerate easily and lift slightly but not enough to allow the bov to activate. I think it might have something to do with not enough fuel for the amount of air being forced in.


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Mine does this too if I'm in 5th and I ease off the gas after acceleration. I just figured that it was the stock dv not fully opening and the pressurized air going back out the turbo.

 

I know what you guys are talking about but that's not the issue. When I'm buikding boost in 5th. Not WOT just slowly, I can begin to hear the vacuum studder.

 

A few things id like to add in. The car is now idiling rough, drops down to about 500 and bounces back to about 750. The car is not tuned at all, but only has a cold air intake and has been driven like this for almost 10k miles. Someone PLEASE give me some input. Thanks

 

Boost or vacuum leak. Start there, check all your hoses, look for cracks. Make sure everything is tight. I suspect you have a leak.

 

Is it always completely visual? I checked them all out but its hard to tell, nothing completely obvious. How else can i check? Buy a smoke leak tester?

 

You can buy or make a boost leak tester. You'll have to hook up an air compressor and put the tester on the turbo inlet. Pressurize, then watch how fast the air pressure dissipates. The flutter that you experience at partial throttle in 5th gear is not all uncommon.

 

Definitely do a boost leak test from the turbo inlet using a compressor/boost leak tester - boost leaks are near impossible to pick up from visual inspection e.g. did mine last week and found a leak at an intercooler clamp and a vacuum hose to the 3 port...visually they both appeared sound.

 

Take it to a place that has a leak tester.