Filled up the 626 with premium last night in preparation for the ZE. I don't want any regular grade fuel left in the tank, so I figured I better start before it's totally go time!
An issue I'd been having for quite a while was that under load (anything more than 40-50% throttle?) the engine just sounded downright terrible, like there was metal popcorn in there, or something. It sounded like something had already blown up and was crunching around. I didn't really put a whole lot of thought or concern into it since I was planning to ditch the FS anyway. I just got used to driving it more like a sane person.
Well, after filling up with 93, the noise seems to be gone. This has really left me scratching my head, as in no way should it require 93. First, the compression's only 9:1 or so, from memory, so that's not an issue. Second, when I started driving it, I put it through its paces, and I would really be surprised if there was a bit of carbon build up anywhere in it, haha. Third, I highly doubt that my minor bolt ons (cai, 4-2-1 Ebay Racing! header, 2.25" catback) leaned out the stock map enough to cause detonation due to it running hot.
This is how my plugs looks quite some time ago, maybe 1-2 years ago (I'm sure it was still making the noise back then as well, it has for so long I can't even remember when it started).
Now, this has left me to suspect that it's a ping/knock/pre-ignition of some sort, but I'm pretty puzzled as to what could be causing it. Maybe it will be time to play motor doctor and pull it apart after the swap!