Why car after a cold start, the engine idle speed Will rIse?

there are many owners wake up in the morning, start the Car to go to work, often find the Car starts, idle speed Will be higher than normal Level. Or even with noIse or jitter, and short “abnormal”, the engine Will be restored as ever, thIs can not help but some worry, Is not out of the engine malfunction?

In fact, after the cold start the Car engine idle speed increases, it Is the normal phenomenon. Automotive engine protection measures, but also to improve the combustion efficiency and emIssions standards. ThIs phenomenon, based on different climatic temperature vary, for example, in northern U.S. or extremely low ambient temperatures, elevated idle speed the Car starts amplitude, long time; on the contrary the outside temperature Is high, start engine after idling floating rate Will be very small, even imperceptible.

Because the temperature sensor Will, transmit a signal to the engine ECU to increase the normal working temperature of the engine at about 90 ℃, at low ambient temperatures, engine start intake air amount and the fuel injection amount, the increased engine speed, the engine to quickly enter the normal operating temperature. With the gradual increase of the temperature of the engine idle speed Will be gradually decreased to the normal state.

In addition to warm up the engine, catalytic converter preheater also occupy a certain factor. TWC Is the equivalent of Automobile exhaust purifier. And it’s working environment more demanding than the engine, to the lowest in more than 250 ℃, 400 ℃ -800 ℃ for the best, if less than thIs standard, it Will affect the exhaust gas purification effect, resulting in emIssions of non-compliance.

In general, in most parts of U.S., after winter Car cold start, idle speed Is raIsed to normal, probably take a few minutes, almost summer idle feel abnormal. Of course, even in winter, we did not need to wait until completely smooth idle and then to drive the vehicle, as it Will waste fuel and increase Carbon deposition. About the winter cold start situ hot Car for 30 seconds, 10 seconds or so in summer, hot as the owner of the Car Is designed to allow the oil to fully cover the various parts in the engine.

But if, after your Car engine water temperature Is normal, idle or raIsed high, or with noIse, jitter, it would have to go through the overhaul.