Your engine doesn't care about your dyno dreams if the air-fuel ratio is wrong. This is one of those fundamentals that separates people who actually tune from people who just bolt stuff on and pray. Whether you're running a stock NA setup or pushing boost through an aftermarket ECU, understanding stoich vs. power enrichment is the difference between making reliable power and cooking a piston. Here's what we broke down: → Why your engine constantly switches between efficiency and power mode → The real story behind 14.7:1 and when you should be nowhere near it → How a single failing O2 sensor can silently destroy your tune → The most common AFR mistakes that end up on the back of a flatbed → How to match your fueling targets to your actual setup The slide most people need to sit with is the one about sensors. You can have the best tune file in the world — if your wideband is reading wrong or your narrowband is lazy, none of it matters. Garbage in, garbage out. Save this one. Next tim...