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      08-25-2017, 09:27 AM   #53
bNks334's Avatar

Drives: '11 135i (N55)
Join Date: May 2014
Location: New York

iTrader: (1)

Originally Posted by WhatsADSM View Post
I'm not sure where you are getting this statement:
"the DME only commands 100% water pump duty cycle at WOT or 108f"

Do you have any data to back this claim up?

The 108*F number you are quoting is the ambient temp to kick into the "High + KFT" table. These tables lower the water temp set point from the normal set point (106C to something much lower). However the data fe1rx posted shows water temps way way above the set point. Any reasonable control algorithm (I'm guessing its PID-based) in the DME should have saturated and be attempting to run the water pump HARD (like full on) to get back down to the set point. Tuning those tables differently will just change the set point (of a saturated control system) even lower... hard to imagine that makes any difference.
If I set my AC in my house to 40*F, I'm sure it won't get there. If I then lower it to 30*F will that change anything? If you are seeing consistent 280*F oil temps on track will a BMS oil temp bypass fix your oil temp problem?

So yea unless I see some real data (best would be actual temp changes from back-to-back tunes, otherwise duty cycle data under an overtemp situation), I am not believing tuning the coolant tables to a lower setpoint is going to help.
You just said it yourself, the table for High +KFT mode is different, and the only way to kick the water pump into that table is to stay at WOT or be over 108f (stock settings). It 100% appears as if the pump is driven harder in HIGH and HIGH + KFT mode. I get what you're saying though... the pump should be at 100% as soon as the car goes over target of 223 (normal mode). However, you can't assume there is enough duty cycle in normal mode to ever hit 100%. Unfortunately, we don't have the pid to log water pump duty cycle with MHD. I can check "torque" or "carly" to see if they have the pid. I know Torque allows you to log the radiators fan speed.

The cooling systems capacity is still exceeded with track driving or even a 4th gear pull even when you force the car into high+kft mode at all times. What's the benefit of coding the tables then? The cars stays in high+kft mode at part throttle, or even off throttle, which allows the car to continue to shed heat down to coolant temps of as low as 180f. When you get back on throttle you now have a much higher ceiling before you get back into that danger zone of 230f+

Last edited by bNks334; 08-25-2017 at 01:27 PM..