冬季氣溫低,高緯度地區更是非常寒冷。當車輛在低溫環境下停放一夜之后,用戶再次起動時會選擇讓車輛先原地怠速作為“熱身”,等水溫表指數超過60℃再駛上道路。然而,網上也有很多言論說,車輛冷起動根本無需暖車。那么,究竟應該聽誰的?
專業人員給出的結論是:
須適當暖車,但切勿暖車過度,
同時還要注意方法。
暖車不當,會帶來一系列不良影響
1.長時間暖車會增加積炭
寒冬季節,冷車時冷卻液的溫度非常低。冷卻液溫度傳感器會將溫度信號傳遞給ECU,作為冷起動時增加噴油量的參考。怠速暖車時,進氣量很低,但由于發動機處于冷機狀態,需要增加噴油量以保持發動機持續運轉,同時為三元催化器加熱。因此,冷車起動后的怠速工況處于混合氣過濃的狀態。如果不稍稍提高發動機轉速加快溫度上升,而是長期以怠速工況來暖車,那么過濃的混合氣會造成燃燒室內的不充分燃燒,形成很多積炭,附著在燃燒室內和氣門周圍。
2.冷車怠速尾氣污染嚴重
上文介紹過,在冷起動后長時間怠速,會使發動機長期工作在混合氣過濃的工況下,這種情況的另一個弊端是尾氣中的污染物含量升高。冷車狀態起動后,發動機逐漸升溫,同時幫助三元催化器提升溫度以達到正常的工作狀態。若發動機總是以怠速轉速運行,三元催化器的溫度提升就會比較慢,尾氣中的污染物也就得不到有效處理。一些車主還喜歡在怠速熱車時,站在車輛周圍吸根煙,那尾氣中的污染物就都被車主自己“享用”了。
3.浪費燃油
冷機狀態下,發動機運轉時的噴油量會增加,這毫無疑問會浪費掉不少的燃油。我們停車的位置多數是在住宅區、車庫或支路的路邊,通常與主干道之間還存在一定距離。與其說任由原地怠速白白消耗燃油,不如讓發動機以低轉速工況,驅動車輛慢速行駛到主干道后再加速進入正常行駛模式。這樣既可以實現暖車,又減少了燃油的無意義消耗,還不會浪費太多我們早上的時間。
推薦的起動、暖車方法
步驟一、接通電源,稍等片刻
將車鑰匙(或起動按鍵)調整至電源接通的擋位,稍等約30秒。全車通電,各個控制單元會完成自檢,同時燃油泵會開始工作,將油箱內的燃油輸送給發動機,恢復燃油系統內的壓力。若不經過這個過程,在冷車狀態下直接起動發動機,通常第一次起動時會顯得有些遲緩,因為燃油還沒有到位。
步驟二、起動發動機,怠速運轉片刻
車輛隔夜停放后,發動機內部的機油幾乎全部都會回到油底殼內。當車輛再次起動,機油泵運轉會將機油再次輸送給發動機各個部件。這需要一個過程,我們不必糾結這個過程需要多久,只需在發動機運轉超過30秒后再讓車輛行駛(提高發動機負載)。這時發動機各個運動部件已經得到機油的潤滑,有效避免嚴重磨損。
步驟三、低轉速緩慢行駛,讓發動機升溫
冷車起動之后,讓發動機以怠速運轉大約30秒后,發動機的怠速轉速會比剛起動時有所下降。當發動機轉速下降并穩定住之后,即可掛擋開始行駛。但此時由于發動機溫度依舊比較低,因此不要提高發動機轉速,應以每分鐘不高于2000轉左右的轉速平穩行駛一段距離,待水溫表指示開始動作,即發動機溫度達到60℃后,再升高轉速,加速行駛。
Professionals give a conclusion that
warm-up is necessary but never over acted,
and in the meanwhile,
it should follow the proper ways.
Improper warm-up will bring about adverse effects
I. Long time warm-up will accumulate carbon deposit
Engine coolant will be in very low temperature when vehicles stop in cold winter. The temperature sensor of the coolant will transfer the temperature signal to ECU as a reference for increasing fuel injection in cold start. When vehicles warm up at idling speed, the air volume intake is quite small, and then the engine in cold state requires more fuel volume injection to keep on running and heat the three-way catalyst. In this case, when vehicles start from cold state at idling speed, the mixture will be over-concentrated. Warming up vehicles at idling speed for long without increasing engine speed to heat up quickly, the over concentrated mixture will not be able to burn completely in the combustion room accumulating lots of carbon deposit in the combustion room and around the valves.
II.Exhaust pollution from cold idling is serious
From the context above, long idling after cold start will leave the engine working in the condition of mixture over concentrated in long term, which gives rise to the high pollutent content in the exhaust. When vehicles start from cold state, engines will heat up gradually, assisting three-way catalysts to raise the temperature to normal working state. If the engine runs at idling speed all the way, the temperature of three-way catalyst will be raised too slow to dispose the pollutant in the exhaust effectively. Some friends even prefer to have a smoke nearby the vehicles which are idling to warm up, in which case, they are actually taking in the pollutents of the exhaust.
III.Waste of fuel
Fuel injection will increase when engine runs from cold state, which for sure wastes plenty of fuel. In most cases, vehicles are always parked in residential areas, garages or roadsides, away from main road. On account of this, it is better to drive the vehicles slowly to the main road and accelerate to normal speed rather than idling in-situ wasting of fuel. In this way, vehicles can be warmed up without wasting your time in the morning and in the meanwhile avoiding fuel waste.
Recommended way of starts and warm-ups
Step one: connect the power and wait for a while
Turn the key (or press the button) to the position where the power is on, and wait for about 30 seconds. After power on, each control unit will finish self-inspection, and fuel pumps in the meanwhile work to transmit the fuel in the tank to the engine, recovering the pressure in the fuel system. Without this process, if the engine is started directly in the cold state, then the first start is usually tardy because the fuel is not in place yet.
Step two: start the engine and idle for a moment
The engine oil will be almost all back to the oil sump after the vehicle parks overnight. When the vehicle restarts, the oil pump will work to transport the oil to each individual part of the engine again, which takes a process. We do not need to worry about how long this process will take, just move the vehicle after the engine runs for 30 seconds (increase the engine load), when all the moving parts of the engine have been lubricated by oil to be free of severe wear and tear effectively.
Step three: drive slowly at low speed to heat up the engine
After the vehicle starts from cold state, let the engine run idling for 30 seconds, and then the idling speed will slow down than when it starts. As soon as the engine speed slows down and gets stable, it is time to gear forward and move. But at this moment, the engine temperature is still very low, therefore it is better not accelerate the engine speed, but driving the vehicle for a while at 2000R per minute. Do not accelerate to speed up until the water temperature gauge moves to show the engine temperature passes 60℃.