Some netizens responded，When I am on a business trip，I will leave my car at the airport overnight。Then the question comes，After returning from a business trip......As soon as the overnight car starts，Idle speed directly 1400;No need to worry about stalling if you put it in gear，No need to step on the accelerator to change gears，You can reach 35 yards in third gear without stepping on the accelerator，I can’t go up to the fourth speed，Obviously struggling;After the water temperature gauge comes up，The idle speed is only over 500。What’s going on，Or is fuel injection smart??

Actually, this is normal，seabet appThat’s called a cold start。90% of engine wear occurs at low temperatures，At low temperature，Especially after leaving the car overnight，The lubricating oil inside the engine will flow back to the oil pan due to gravity，At this time，If you start the engine，The engine wear is the most serious，Generally speaking，The engine oil pump is connected to the crankshaft or camshaft，As long as the engine is running，Crankshaft rotation，The mechanical oil pump will quickly pump oil to the lubricated parts，But，Due to the high viscosity of engine oil in low temperature environment，Poor low temperature fluidity，Many parts that rely on splash lubrication have poor lubrication effects。

?After a night，Start at work the next day，It is found that the speed is always maintained at 1200 rpm，When driving normally, the idle speed is only 800 rpm，Nothing to worry about，This is a control strategy specially set by our designers in the CPU，The purpose is to speed up the car heating，After the water temperature comes up，The speed naturally decreases。This can reduce the working time of the engine under poor lubrication conditions。It is not an idle speed fault。

?Because there are many disadvantages when the car is cold，So the engine computer will increase the idle speed，Increase fuel injection volume，Raise the water temperature as soon as possible when you come。When the water temperature rises slightly，Idle speed slowly decreases，The high idle state lasts about 1-2 minutes，The lower the water temperature，The longer the duration。

How does the driving computer seabet appknow it is a cold car?It has a sensor，Called water temperature sensor，Rely on it for real-time monitoring，If it is too low, the fuel injection volume will increase，If it is too high, it will alarm，Displayed directly on the dashboard，Water temperature alarm light on，Once lit，Need to stop immediately。

?When the car is cold，Due to the low temperature in the cylinder，Poor atomization of gasoline，Necessary conditions for combustion，The engine will require an increase in the concentration of the oil-air mixture，So the engine will increase its idle speed，To increase the amount of fuel injection，Increase the concentration of oil and gas mixture，As the cylinder temperature increases，There is no need for an overly rich oil and gas mixture，Then the idle speed gradually decreases，The engine fuel injection volume is also gradually reduced，Wait until the engine temperature is completely normal，ECU will maintain an air-fuel ratio，It is the best ratio of air and oil for complete combustion。At this time, the engine enters closed-loop operation，The amount of fuel injection is no longer based on the water temperature sensor，Instead, the fuel injection amount is adjusted according to the level of the oxygen sensor in the three-way catalytic converter，To achieve the best state of complete combustion emissions。