Same thing here 1st noticed it after my EcuTek flash defiantly starts lower in the rpm band the colder the intake air temp is. I was thinking it was wastegate flutter or something with the exhaust. I have PCMScan so i can post some logs too. What would be the most useful PIDs be in order diagnose this?

 

I have noticed the same thing, but only when the car isn't warmed up fully, or when it's really cold outside.

I don't ever rev high when the car isn't warmed up properly, or even go about around 3000 rpm when the car isn't warmed up. Never WOT when cold. Seems to be a temperature thing.

 

I have a GSR with 16000Km on it doing the same thing. Problem started when the average ambient temp was 4 Degrees Celsius, so im not sure about the corelation with the cold weather.

The car did it completely stock in 3-5th gear at wot. With the accessport stg 1 91oct map i still get it but not as bad. Its defintetly pulling power when it does this.

 

I have the same problem but it happens when the car is warmed up at wot throttle from 5k to redline. I notice it more after I shift hard from 1-2 and 2-3. My car has Ecutek, mbc set at 23-24, and k&n filter. Hopefully someone will figure this out.

 

my viii does this here in denver. its been pretty cold out and it tends to do it more than when its warm. i believe its the wastegate not being able to hold. my buddy has a diesel truck that does the same thing at full boost.

 

My IX has an occasional rough idle when it is cold, after doing some hard acceleration. When the weather is warm it's smooth.

 

My GSR with 25000km on it was doing the same thing, I thought it was coils and spark plugs because of how rich they all were running at the begining, my clutch then went out totally.....so it was clutch slip......it's weird though because there was no smell of clutch prior to this and it was unlike any clutch slipped i've experienced in similar cars

 

Have a 14,000 miles GSR doing the same thing, just realized it started with the weather change but as like others, am not sure if they are correlated.

 

This is due to the weather. The car only does this in cold or when the car has not reached it's optimal operating temperature. Solution start the car and let it run for just a few minutes (2-3). Then drive below 3k rpm for a few first shifts and by that time unless it's very cold outside car will be good to go. Anyways it works for me.

 

my GSR does the same thing when it's not fully warmed up but after that it's fine

 

Hmmm....my fluttering has occured in 3 seasons so far (summer, fall and winter) both on warm and cold days. Also, I get the fluttering sound when the engine is cold and also after extended periods of driving.

 

my 2004 gsr with 55k miles does this too. I just noticed this morning, about scared the hell out of me. Car was warmed up for at least 5 minutes then when getting on the beltway in 5th gear wot around 5k rpms and higher it feels like the boost is cut then once it "cuts" it starts to build back up. I got the car used yesterday and never noticed this because on the test drive i never took it up to 90 mph 5th wot. It sounds like boost cut, now just need to figure out the reason. I inspected the engine bay for a manual boost controller and never found one. I'm wondering if the previous owner had the ecu flashed... time to take it to a mitsu dealer and have them check it out. Oh well it's worth it, once I get all these kinks worked out

 

Searched for wastegate flutter and found this thread.
I hear flutter when on the pedal and boosting, but not WOT. I really notice it will driving at highway speeds or at least above 30mph and giving it enough gas to hit some decent boost.

Planning on logging with the AP in the next few days while trying to replicate the flutter, and I will post if I see anything out of he ordinary. The issue only came up after getting the car tuned at Cobb so I may need to go back for some fine tuning....maybe I can talk the wife into buying me a TBE to make the 4 hour trip worth while.

 

Just tested it out at 68 degrees, and the fluttering is significantly reduced....but I can still hear it .

 

Yep def. less noticeable when it's warmer outside.