Here's a video of the issue.
https://youtu.be/pw7i13hSIL0Just for reiteration, I just installed a catted downpipe. This boost flutter happens at moderate throttle, low RPMs, and with moderate load. It happens with the stock calibration, my last revision custom tune, and with the updated custom tune to correct for the downpipe. Attached is a log. You can see it happens 3x a second.
I noticed this with the stock calibration prior to the downpipe when locked in 6th gear going 65 in the mountains. It happened occasionally with my custom tunes, but never this dramatic and only when really lugging. Now it occurs with all of my prior custom tunes and with the updated ones.
It sounds like the BOVs are dumping boost. If you look at the logs, the throttle angle and the wastegate increase just after the boost deceases, mostly.
Here are my working theories:
1) BOV solenoids (one or both) are failing. 2012 F-150 here, so mechanical BOVs.
2) Wastegate solenoid is failing. You can see the WG percentage sometimes falls when the boost falls, but not always, so I'm thinking the sharp increase is more of a compensation.
3) Wastegates are mechanically being blown open due to weak springs and the decreased backpressure with the new high flow downpipe made this worse.
Not too long ago I cleaned my MAP sensors and placed clamps on all my vacuum hoses. I also checked for any cracked lines or connections.
I still can't put my finger on why the throttle angle would change with the oscillation of boost like it does.
Any ideas here? I want to be excited about my new downpipe, but I'm really feeling kind of bummed.