I followed some advice you gave about putting a gallon of E85 in with our crap CA 91 and it really helped with the negative corrections, so, thanks!
Glad it helped! Remember, if you don't run your tank empty every time, but still add a gallon at each fill-up, eventually you'll work up to a much higher ratio of E85 to premium fuel. I tend to add the gallon and a half of e85, go through 2 tanks of fuel filling at 25% remaining, then on the next fill-up add a gallon to a gallon and a half again.
At what point would you be concerned about knock? I stopped monitoring so I would t drive myself crazy, but I got 1 knock count on my 20 minute drive to work today.
I'm not the be-all end-all of tuning, but I recently posted a thread about occasional part-throttle knock/corrections (and got some great feedback) as well as contacted Dizzy about it (I am also obsessive about research. Literally.). The takeaway was, the occasional part-throttle knock isn't a good thing but it's not necessarily bad. If it's extremely infrequent AND it does not happen at full throttle AND your OAR stays in the same place all the time it's *probably* ok. If you're running a specific tune, it might be worth poking the tuner just to confirm. Jason@Dizzy said they could pull more timing in the midrange to compensate for me being lazy and lugging in third, I decided to just shift more. Totally called out
This was enlightening as well:
https://stratifiedauto.com/blog/und...ons-in-your-high-performance-ecoboost-engine/
Also, false knock:
- my MBRP was occasionally hitting the mid-chassis brace, and would trigger a knock/correction.
- My 2J intake would occasionally flap around, and I'd hear it think then immediately see a correction as well.
This is all still new to me, with new-school electronics you can safely run *much* closer to the edge than what I came up with - for me, we did maps based on pure AFR's and either tuned super tight for a specific gas station/grade of fuel, or tuned conservatively enough that nothing would blow up if we went to a lower tier gas station.
My part-throttle negative correction isolation/remediation process went like this:
1. Stop boosting at 3k rpm, be less lazy and downshift more = fewer neg corrections on hot days.
2. Replaced 12k mile old sparkplugs = even fewer neg corrections on hot days.
3. Added a gallon and a half of E85 to a full tank of gas = almost no negative corrections.
(car ran great, smelled like fuel more after stopping though. Not sure if related)
4. Avoid a bumpy road by my house that makes the MBRP hit the chassis brace = no negative corrections.
4.1. Went over train tracks on the way home from testing, MBRP thumped, instant negative corrections/knock.