Can an engine run normally without an ECU?

[CadenLynn]

An engine cannot operate normally without an ECU. The ECU is referred to as the brain of the engine. There are numerous sensors and actuators around the engine, and the ECU can collect data transmitted by various sensors. After processing, it controls the engine operation through actuators. The ECU is a computer board fixed within the engine compartment, which can be located after opening the engine hood. The ECU's housing is made of metal with certain waterproof capabilities, and there are some heat sinks on this metal casing to assist in dissipating heat. When washing the car, avoid directly spraying water into the engine compartment with a hose, as this may damage the ECU and electronic sensors inside the engine compartment.

[Katherine]

Over the years I've driven, I've handled many classic cars like the vintage Beetle or old pickup trucks—they ran just fine without any ECU. Those engines were purely mechanical, relying on carburetors for fuel delivery and distributors to control ignition timing, with power transmitted solely through connecting rods and gears. Though acceleration was a bit sluggish and fuel efficiency wasn't great, as long as you regularly maintained the carburetor and checked the spark plugs, the engine would keep turning reliably, even on long trips. Modern cars incorporate ECUs to boost efficiency, but these older designs prove that an engine's core functionality doesn't depend on computers. Sure, today's road conditions are more complex, and vintage systems might hiccup during rapid acceleration or cold starts, but fundamentally, they can still operate mechanically.

[LaFrank]

As a daily driver, I heavily rely on modern technology. Without the ECU, the engine would basically be paralyzed. The ECU acts like the brain of a car, controlling critical aspects such as fuel injection quantity and ignition timing. Without it, sensor data would fail, injectors might spray too much or too little fuel, and spark plugs would fire unevenly. The result would be an engine that won't start, runs rough, or even emits black smoke. Modern car designs integrate ECUs to meet emission standards and improve fuel efficiency. Just as the mechanic at the repair shop told me last month, an ECU malfunction directly triggers the check engine light and causes sluggish acceleration while driving. Older carburetor-equipped cars might barely run, but they're inefficient and unsafe.

[DelValeria]

Over the years of repairing cars, I've seen many cases of ECU issues. Without the ECU, the engine runs unsteadily. The ECU controls fuel injection timing and ignition sequences. Without it, the system loses control, fuel combustion becomes incomplete, emissions exceed standards, and it may even cause engine knocking. Simply put, if the ECU fails, the car stalls. I often replace old units to solve this. Older designs like carburetor engines could run without an ECU, but that was years ago. Nowadays, new cars simply can't function without it.