In early fuel injection systems, you would manually adjust the mix for a base setting on fuel/air ratio. I still have a long 3mm hex key wrench that just fit a Bosch K-jetronic fuel distributor to adjust the mixture. Once in closed-loop, the fuel injection could compensate a bit based on O2 sensor readings, but the base fuel/air ratio had to be correct or it just wouldn't run right.
I think the guy has it backwards. In the 80s, gas was gas. No ethanol. Oxygenated fuels followed in later years. MTBE worked great but was a horrible groundwater poison, so everyone moved to ethanol. An ethanol mix, while higher in octane, requires just a bit more fuel in the fuel/air ratio. So, he should've been loosening that spring.
But those springs can age a bit, and perhaps he was adjusting air/fuel ratio to compensate for worn parts, while thinking that he was compensating for modern fuels...
I think the guy has it backwards. In the 80s, gas was gas. No ethanol. Oxygenated fuels followed in later years. MTBE worked great but was a horrible groundwater poison, so everyone moved to ethanol. An ethanol mix, while higher in octane, requires just a bit more fuel in the fuel/air ratio. So, he should've been loosening that spring.
But those springs can age a bit, and perhaps he was adjusting air/fuel ratio to compensate for worn parts, while thinking that he was compensating for modern fuels...