I have both car and motorbike. Just common car and motorbike. My car is Toyota 2005, and my motorbike is Honda 2016, I bough both brand new. Both them are fuel injection. Before them, I owned car and motorbike, but both them were carburetor. With those old automotive, I have to warm the engine up until they reach their stationary. The requirement time will be around 5-10 minutes, depend on the weather and time. Morning in rainy season will be different to day time in dry season, however.
With my new automotive that are fuel injection, my habits still there, I still need to take that time to warm up the engine. But I read in many occasions in automotive news said that for fuel injection just required half and maximum one minute to warm up. For my car, since I start the engine up, it will go to around 1,300 RPM, and required around 7 minutes to become stationary, around 700 RPM. The stationary's RPM is clearly stated at the engine cap, with a yellow poster posted there. For the motorbike, I have no idea as no stationary indicator. But another car, Honda, I saw that it takes shorter time, and one Mazda car I saw just required around half to one minute to warm up, as said in the automotive news.
In my understanding, warm up is intended to warm the engine up slowly to avoid the engine's temperature changes so quickly that of course is not good for the engine itself. So my question is, how that warming the engine could be so different? And what is actually that warming up intended? Several time I tested my car without proper warming up, the result is very bad, something like knocking in the engine.