New cars are confusing. With all the computers, sensors, and gadgets, it may seem like there’s some sort of magical witchcraft taking place under the hood. We’re here to show you how modern automotive computer control systems work. Last week, we looked at variable valve timing. Today’s topic: Electronic Fuel Injection. Back in the day, a good ol’ carburetor was responsible for sending the appropriate amount of fuel into the cylinders. Today, that job belongs to the ECU. For a lot of you this is review, but if we want a new generation of car enthusiasts to care about cars, it can’t hurt to explain how they actually work. If the heart of a car is its engine, then its brain must be the Engine Control Unit (ECU). Also known as a Powertrain Control Module (PCM), the ECU optimizes engine performance by using sensors to decide how to control certain actuators in an engine. A car’s ECU is primarily responsible for four tasks. Firstly, the ECU controls the fuel mixture. Secondly, the ECU controls idle speed. Thirdly, the ECU is responsible for ignition timing. Lastly, in some applications, the ECU controls valve timing. Before we talk about how the ECU acco...