blackspyder

A friend at work and I both d when rive 95 f150s (his is actually why I bought mine, so much better than a 05, goodbye electronic junk)
His is a 5.0 mine is a 300 i6, both get excessive spark knock when we run less than 93 octane e10 fuel (we get fuel at different locations and brands). I started running "rec fuel" in mine and saw improvements over 93 octane e10.
It's not exactly convient or cheap. Is anyone else noticing issues or just us

Crownman

Check your timing. Make sure the engine isn't running hotter than normal. check your plugs. And while the plugs are out use a flashlight to see if there is excessive carbon buildup on the pistons.

fltdriver

x2, I would be willing to bet someone did the "6-liter tune-up", maybe didn't quite know what they were doing and advanced the timing too much or it's time for new plugs. During the spring/summer/early fall I use 89/10%e because I go through so much gas anyway that it won't have time to draw in moisture. I do run seafoam in the 2nd to last tank before oil changes to clean out any crud from the ethanol (1/3 in gas, 1/3 oil, 1/3 slowly through the brake booster hose). During my slower consumption time I run 89 with no ethanol. With both I don't have any knock.