A good ECU would look at the temperature of the incoming air and increase the amount of fuel for colder air. If you're already pushing the limits on what the engine will tolerate, though, you'll need more fuel when it's hot as well to prevent ping.
For a given air fuel ratio, the colder the charge temps, the less chance of detonation. If you're not going to have a "summer tune" and a "winter tune", then you need to have one tune that applies to all situations, including one with crappy gas. That means not pushing the ignition timing up and dumping a little extra fuel to keep things cool and rich.