I have a 4EAT with a 20G, along with the APS TMIC/BPV (among other crap). I've noticed lately that when I get on it, the "whoosing" sound isn't consistent. I appear to be hitting target boost, but maybe a little later than I should be as well. The noise is like the airflow isn't consistent. It fluctuates while I'm accelerating on WOT. The car doesn't buck, but it does seem a 'bit' sluggish. I have my normal wastegate flutter, so it's not that. From what I've heard it really doesn't sound like compressor surge either. It sounds like it's possibly the bpv. Since it's the APS, it's fairly quiet when it releases, and being a 4EAT, it works a little differently than a manual. But to me, I just feel like it may be stuck or something. Anyone have any ideas or similar issues? Thanks, -jfk
My guess is that with the auto transmission, your going foot to the floor acceleration, so the throttle body doesn't close - what ususally would cause a bov or bpv to have to release pressure from the turbo. The slowing of the engine from shift to shift would maybe make the bpv have to work a little, but not as much as if you had let your foot off the gas (shift in manual tranny) .
i dunno if this helps, but my APS with TMIC makes different noises than most BPV/BOVs. part throttle is sometimes sounds like a deep intake note (noise). have you messed with your spring? ..and yeah, the pshhhhh (BOV) noise is audible only at WOT, but mine has been cranked down completely since I bought it....before my tune. If your spring was adjusted after your tune that will have an effect on the wastegate duty cycle..IIRC
Nope, haven't adjusted anything since the tune. But that's been about 2 years. It just seems like it's struggling. It's not a consistent build up of noise. It falls a bit...flutters if you will, but sounds nothing like WGFlutter or compressor surge (at least from the examples I've heard). It usually happens on WOT around the higher revs or past 14-15 psi. Peak boost for me is 19psi on pump.
I know this is wayyyy out there, but we need to take into consideration that it's mucho warmer out = less HP, less response. (More of a blanket statement rather than an answer to your problem)
I understand the physics, but I noticed this during the winter as well. It just doesn't sound normal...it's not way off from normal, but I would think that when my boost is building, the noise should be stable, as it used to be Would I be logging a leak if the BPV was stuck open at all? Cause even though I thought my AF learning values were back to normal, unfortunately, they aren't. I'm back to hitting 15% at idle :-/
