我在國外論壇有人討論到類似的問題,但是他不正確使用了不當的低溫水龜造成DTC(錯誤碼)
在原廠電腦設定的warm-up time內未達target ECT temperature,會有DTCs產生 DTC P0128 (coolant temp below thermostat regulating temp)
我擷取一部份文章給大家看看!
I'm working on a 2003 Ford Focus that came in with the MIL on and a DTC P0128 (coolant temp below thermostat regulating temp) stored in memory.
You can understand why a vehicle manufacturer would want to make engine warm-up go as quickly as possible, and why OBD II has a monitor that's designed to determine whether engine warm-up is going according to plan. And even before the engine reaches operating temperature, oxygen sensor heaters make sure the sensors are wide awake and doing their jobs as soon as possible (literally within seconds).
Prior to the DTC you're dealing with, other Ford vehicles had a monitor that would store a DTC indicating "insufficient temperature for closed-loop." You wouldn't necessarily know how long the engine had been trying to reach the proper operating temperature, only that it had failed to do so. Let's look at how the monitor works for your customer's P0128. If the engine is being operated in a manner that is generating sufficient heat, the engine coolant temperature (ECT) should warm up in a predictable manner.
The test runs if the start-up intake air temperature (IAT) sensor is at least 20°F, and below the target ECT temperature. The timer is incremented to begin while the engine is at moderate load (30%) and vehicle speed is above a calibrated limit (15 mph). The target/minimum timer value is based on ambient air temperature at start-up, measured by the IAT. If the timer exceeds the target time (between 300 and 800 seconds) and the ECT has not warmed up to the target temperature, a malfunction is indicated.
The target temperature is calibrated to the thermostat regulating temperature, minus 20°F. For a typical 195°F thermostat, the warm-up temperature would be calibrated to 175°F. So if the monitor time period expires before the ECT temperature reaches 175°, the PCM will store a DTC.
The thermostat must impede coolant flow when the engine is cold, to help it reach operating temperature as quickly as possible. This function becomes especially important in cooler ambient temperatures. If the thermostat is unable to close completely, the partial coolant flow through the radiator may be enough to keep the engine from reaching the target ECT temperature within the monitor's allotted time window. In addition to failing the monitor, your customer's complaint about sluggish engine performance is probably due to the fact mat the engine is not reaching the proper operating temperature.
If the thermostat is stuck wide open, the engine may never get warm enough to enter closed-loop fuel control.
看起來,水龜本身硬體的全開溫度是195F約90度,原廠工作溫度是175F約攝氏80度
有沒有人同意呢?
如果同意,比較適合的水龜應該高於80度以上,83~85度水龜可能比較適合改裝!
另外一個參考資訊 cosworth full engine
在2.0的引擎,在220p以下採用82度的低溫水龜 ,250以上採用70度的低溫水龜
在2.3引擎,在250p以下採用82度的低溫水龜 ,270以上採用70度的低溫水龜
http://www.mmsport.com.au/download.php?fid=35