What grade of fuel are you using with your MS Boosted or not in an NA
 

I'm having a few issues, and it made me wonder about fuel grades. What grade of fuel are you using? Which engine, is it under boost, and what type of climate do you live in?

Sunoco Ultra 94

Edit. Sorry I missed the "MS" part of your question.

91 octane around town, Sunoco 100 on track. 16psi. 70°-90° temps typical.

In So Cal, 91 (R+M/2) for everything from daily driver to AutoX to canyon-carving in the desert. Ambient temps anywhere from the 70s to the 100s.

In Florida, 93, for all the same uses the the obvious exception that we have neither mountains nor canyons here. Ambient temps commonly in the mid to upper 90s.

1.6 engine, running ~13 PSI on a small turbo, with FMIC and half-assed water injection.

Chevron 91 for 2 years. Draining the tank and switching to whatever 100 octane is on tap at the track I'm at.

Did you ad a drain to your tank, or are you using the pump to evacuate the 91 through the fuel line?