Subject	ECU Fan Control
Posted by	zromtech on April 08, 2016 at 5:49 PM
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In Reply To	Using Efan with OEM ECU on TT posted by NIVO88T on April 07, 2016 at 06:59 PM
Message	Thanks, excellent write-up! I just want to point out that there may be a few inconsistencies between how the ECU controls the fans and how you've explained it. Rather than go into detail over how Nistune may be incorrect, here's how I handle OEM fan control in the ECU tuning software I am developing: I've found that the simplest way to explain the OEM fan control algorithm is by using a table of coolant temperature vs. vehicle speed. The high/low/off fan-speed activation temperatures are all based on the 90°C 'Temperature Threshold' constant and are spread over five distinct ranges in 5°C increments. Adjusting the base temperature threshold changes all of the other temperature ranges, respectively. Likewise, the two vehicle speed constants affect the fan activation in three vehicle speed ranges. For example, here I changed the activation temperature with the AC OFF to 80°C, and enabled the fan at vehicle speeds from 0 to 20kph using the 'Fan Speed - AC OFF' table: Note that the fan will always turn on HIGH at the activation temperature + 15°C, regardless of vehicle speed. Also, the fan on/off hysteresis value to which you refer is actually a *time* constant and not temperature. Since the timer resolution for the fan is 100ms, the OEM value of 50 equates to 5 seconds. - Sam
Follow Ups	Using Efan with OEM ECU on TT - NIVO88T 18:59:23 04/07/16 I dont want to offend... - -Grimm- 09:56:25 04/08/16 Re: I dont want to offend... - NIVO88T 13:03:07 04/08/16 ECU Fan Control - zromtech 17:49:13 04/08/16 Re: ECU Fan Control - NIVO88T 00:58:29 04/09/16
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