Torque dip sound: rattling / vibrating
 

With certain tunes / mods I hear a difference in the torque dip area.. like a rattling / vibrating sound, and then it smoothes out again. I've heard that resonance and air dynamics play a large role in torque. Am I hearing the loss?

I heard it more prominently when I got an intake, then it went away when I installed my cat back exhaust. With it I felt the dip go away. Could you say it's 1:1 or it's just mildly related?

The sound your hearing is coming from large overlap made possible by the AVCS system. When trying to maximize power on these cars you run alot of overlap before and drop it off then ramp back up through the TQ dip to minimize the valley itself. I have only been tinkering with it for a few hours since I just got ECUflash beta last week.

But dropping the overall overlap and smoothing out the ramping up and down makes this go away almost completely without effecting the reduction in the tq dip.

I like the sound personally.

But it's when I hear this that I loose power.. so it's negative reinforcement. Are you gaining power?

Aha.. I knew a little about AVCS but you've got me researching now. This sums it up pretty good if anyone else is interested: http://drive2.subaru.com/Win05_WhatsInside.htm

Thanks!

oh...ya it's when my power goes weeeeeeeeeeeee right at 4k (thanks to my tune)

First day I drove home with my (at the time) new tune and noticed the sound, I was a bit nervous. Now I think it's awesome! I confirmed with my tuner, it is indeed from messing with the timing. All I know is, I've got a lot more power in the dip than I did before...