Recent knock events stopped after unplugging the EGR and putting the car in limp mode. Is this most likeky a result of the EGR not working or the safety map? [2018 WRX FA2O]
I have been troubleshooting some recent FBK/FKL/DAM drops and found a post with ide tical symptoms pointing to a faulty EGR valve. To help test this, I unplugged the EGR with the car off to, hopefully, have it fail closed.with the EGR unplugged and running in the "safety/limp mode" map, DAM climbed back up from 0.514 to 1.000 and remained steady for a few weeks.
I replaced the EGR valve, plugged it back in, and it was fine for about 3 days, which seems to be the common threshold for smooth driving. It's as if the car will be perfect after resetting learning for almost exactly 3 days and the on the 4th it will start picking up -9 FBK/FKL and eventually reduce timing. I can always feel the timing pulls as well. No audible pings or anything like that. AC compressor is always off.
This makes me think that the root cause was solved by running the fallback safety map when the EGR was unplugged rather than it being related to the EGR. That kind of points to a closed loop issue. At this point the parts cannon has provided a new MAF sensor, new front and rear O2 sensor, new EGR solonoid, new spark plugs, walnut blasting intake valves, among other small things.
I'm about to take it to a shop next week if they have availability, but what might be the issue? Could it even be the tune now given most sensors were replaced? I haven't found any air leaks with the smoke test I ran, but that was only a 1PSI test so not sure that would find small vaccum leaks.
More detailed I for on some of the above changes in another thread I posted a while ago: https://www.reddit.com/r/WRX/comments/1nsrpul/intermittent_stutteringhesitation_during_low/