Maybe this is normal and I never noticed or maybe a boost leak...

Under 40% to hard acceleration I can hear a fluttering sound. It's not when I let off the gas but when I am on the gas. I can hear it in the cabin with the windows up. This is after I ran through the gears very hard the night before.

All stock except for AP

Any ideas or is it normal.

 

Do you have a GSR or MR? Mine is doing this too, and I logged it. The flutter is clearly visible in the log.

https://www.evolutionm.net/forums/ev...logs-pics.html

 

I was just reading you post and came here grab my URL to do the same thing. It's a GSR with 1700 miles and didn't do it until two hard runs the night before. It sounds like we have the same problem.

 

My EVO IX did that under WOT when it was really cold out. I believe but don't quote me, it may be related to overboost. My 04' STI did something to a different affect under really cold conditions, fuel cut.

The fuel cut felt like you hit a brick wall, the over boost on the EVO got a fluttering sounds and power loss that could be felt. Haven't felt it in my X yet, completely stock and I rarely take it past 4-5k.

Might want to add on my IX, had TBE with test pipe.

 

edit

 

I just replied to the other thread, but my guess is compressor surge due to it only happening in the upper gears. The boost control tables may need to be adjusted to limit boost in the lower rpm range.

 

Thanks for the replies. My car does this in every gear and it's a GSR not a MR as the other posters is. It was very cold out when it did it and I haven't had a chance to drive it again. Next time I do I will get some logs and post them.

 

My car is doing the same exact thing right now. Seems like the car is REALLY sensitive to changes in weather. I'm getting my boost tables revised this weekend...I'll report back with the results.

 

Most likely the boost correction is kicking in to limit the amount of boost. Either the initial wastegate duty cycles (primary & secondary) need to be dropped or the boost correction needs to be raised.

 

This is as well happening to me, or happened to me. I had an intake and manual boost controller set to about 23-24psi tapering down to like 20-21 psi. I had always thought it might be the wastegate fluttering due to higher boost and the wastegate actuator was not strong enough to keep it closed. but i put on a cat back exhaust and its non existent now im assuming to the loss of back pressure and better flowing exhaust. or i could be totally wrong. good luck

 

It's not surge. You would experience that at low rpms and more so while letting off the gas.

I would say it's an exhaust leak. Does the car smell like exhaust when you lift the hood?

 

its strange. it does it to almost everyone here and no one knows where its coming from and how to fix it...mines been doing it ever since i replace my cai.

 

Boost is being dumped

 

My car is doing the exact same thing......it started when i drove it in cold weather for the first time......it's like the boost drops off for a second or two aroung 3500 rpm and then comes back suddenly? i just don't know y it would be doing that

 

Similar fluttering here but mine is at higher rpms (5000-7000) at WOT in 3-5th gears and at since it flutters all the way to redline you don't feel boost coming back on. Mine started a couple of months ago.