In the operation of each car there are moments in which the engine does not receive any load, except for friction, but they are present directly in it, which means that they are part of it. To avoid these forces, various lubricants are used, but still they remain.
This engine operation is called "idle." At this time, the gearbox is not engaged with the input shaft, so the rotation of the crankshaft is not transmitted to the wheels. But do not think that the car must be standing in order for the unit to idle under the hood. Many drivers use the so-called reel to save fuel. For example, a hundred meters remained before the turn, and the speed is high, then you can turn on neutral gear and "roll" by inertia. On the one hand, this is an economy, on the other hand, it was possible not to accelerate to such a speed that it probably took even more gasoline or other fuel that the car engine uses.
Idling plays an important role in operation, since in this mode the engine "lives" a significant part of the time. This means that before we get started, we turn on the transmission, it takes some time. For one inclusion it is small, but if you count all the gear changes per day, week, month, year ... The figure is pretty impressive.
In fact, the engine idle can tell about its condition. First of all, if the idle floats, then this means that some system is not working correctly, not as it should. For example, it is worth thinking about adjusting the carburetor or checking the electronic control unit. In addition, there may be problems with the ignition, which is quite easy to check. In this case, you just need to make sure that the ignition timing is set correctly , as well as the clearance rate. If everything is in order, then you can go further. Idling can be impaired due to a malfunction of the fuel pump, especially high pressure. In this case, it will be pumped up, but not enough, which leads to unstable work with interruptions. You should also make sure the tightness of the entire fuel system, since air entering it is fraught with the same consequences.
In addition to the fact that the engine should work "without assistance", idling on a warm engine should not exceed 900-1000 rpm, which is an average indicator, it is lower for some engines. If idle is observed, but it begins to “float” when reduced to this norm, it is worth considering the condition of the piston group. First of all, about piston rings. Their wear, as a rule, is accompanied by increased fuel consumption, as well as a serious drop in power at low speeds. In addition, the piston rings wear out the same way, which means that the oil scraper wears out along with the compression rings, which leads to an increase in oil consumption. This can be seen by periodically checking the engine oil level.
The reason for such a check should be blue smoke from the exhaust pipe, which is simply impossible not to notice. In conclusion, it is worth saying that idling is a serious work that must be maintained in good condition, like other car systems.