CSL tune aux fan curve location?

[repoman89]

Just did a 16" spal with the oem fan controller and am deleting my front pusher fan today and noticed my fan is not kicking in as hard as I would like it to for it to do its job in the hot summer days at low speeds. Well thanks to this thread I just confirm something a little terrifying... I did a comparison of the KL_ELU_TKA of stock CSL fan temp settings and Z4M and the Z4M settings are bad news on our car. If you look at the first table of values (stock M3) and then compare to the second table (Z4M), you are actually screwing yourself over by running these "Z4M settings" because the fan doesn't even kick in at 100% until 215 degrees F. With stock settings that happens 20 degrees earlier which could be the difference in your car overheating when its not moving as you're giving the engine less time to cool itself before it reaches dangerous temps.

I am really glad this thread came about because I am going to go back to stock fan temp settings and datalog just to see and I bet that is why my coolant needle on the dash is hitting 3/4 dot at around 98c. This is also great because thanks to you all we have also debunked the hilarious misinformation that the stock fan controller can not reach 100% fan speed because clearly its a programming issue and not a hardware limitation.

Now question for you all... I am looking to mess around with the parameters to improve the cooling efficiency of the fan in traffic and when idling as well as low speed situations after railing on the car on the track etc so the engine gets the airflow it needs. My car still has AC so it sounds like the primary function to tinker with is the KL_ELU_TKA and potentially lower the temps for the fan to start spooling up.

The other two functions for fan speed based on AC load K_ELU_KK0S_Xof16 and K_ELU_V which is based on vehicle speed may also add some value in traffic in the summer for that rare occasion, but I was unable to find these parameters in Tuner Pro when using the parameter finder function. Any insight on where these are located?

Stock E46 M3:


Stock Z4M:

Yeah, you discovered what I also discovered and forgot to post. I made my own table since creating a reasonable fan curve isn’t rocket science. I have it turning on 100% by 82C at the moment, decreased recently from 85C because the needle would get to the middle parking in the paddock at the end of a session. I don’t think there’s a benefit to having it start to spool up any earlier than 39C or whatever the lowest value is and I also didn’t feel there would be any benefit to messing with the speed multiplier since BMW presumably tested vehicle speed vs airflow and set that appropriately.

There’s also a max PWM value that was set for me to 0.9 (can’t remember the K symbol for it). I increased to 0.95 since the SPAL fan draws less power at full tilt than the aux fan.

[thegenius46m]

Just did a 16" spal with the oem fan controller and am deleting my front pusher fan today and noticed my fan is not kicking in as hard as I would like it to for it to do its job in the hot summer days at low speeds. Well thanks to this thread I just confirm something a little terrifying... I did a comparison of the KL_ELU_TKA of stock CSL fan temp settings and Z4M and the Z4M settings are bad news on our car. If you look at the first table of values (stock M3) and then compare to the second table (Z4M), you are actually screwing yourself over by running these "Z4M settings" because the fan doesn't even kick in at 100% until 215 degrees F. With stock settings that happens 20 degrees earlier which could be the difference in your car overheating when its not moving as you're giving the engine less time to cool itself before it reaches dangerous temps.

I am really glad this thread came about because I am going to go back to stock fan temp settings and datalog just to see and I bet that is why my coolant needle on the dash is hitting 3/4 dot at around 98c. This is also great because thanks to you all we have also debunked the hilarious misinformation that the stock fan controller can not reach 100% fan speed because clearly its a programming issue and not a hardware limitation.

Now question for you all... I am looking to mess around with the parameters to improve the cooling efficiency of the fan in traffic and when idling as well as low speed situations after railing on the car on the track etc so the engine gets the airflow it needs. My car still has AC so it sounds like the primary function to tinker with is the KL_ELU_TKA and potentially lower the temps for the fan to start spooling up.

The other two functions for fan speed based on AC load K_ELU_KK0S_Xof16 and K_ELU_V which is based on vehicle speed may also add some value in traffic in the summer for that rare occasion, but I was unable to find these parameters in Tuner Pro when using the parameter finder function. Any insight on where these are located?

Stock E46 M3:


Stock Z4M:

[eacmen]

I think we're stuck with what BMW did. Is the engine outlet temp available to the DME?

I ended up setting the 100% temp to 82C or something close to that. Sounds like maybe I should reduce it further.

My use case for the aux fan is 100% in the pits waiting to pit out on track. So I may need to optimize the fan curve for this scenario.

I also just deleted the puller mech fan. So the pusher is my only source of airflow.

[repoman89]

I think we're stuck with what BMW did. Is the engine outlet temp available to the DME?

I ended up setting the 100% temp to 82C or something close to that. Sounds like maybe I should reduce it further.

[eacmen]

Bump for this. I read the link on github several times.

The table in the ECU is basing Aux fan duty cycle on radiator outlet temp? At idle with A/C on I generally see about a 40 degF difference between rad outlet and engine outlet. So the aux fan wont reach full duty cycle until 90 degC (194 degF) radiator outlet temp? From the data I gathered today that would mean that the engine outlet temp could reach 235 degF before the aux fan kicks in full speed?

Wouldn't you want to base the Aux fan duty cycle on engine outlet temps?

[repoman89]

The Z4M did not use the MSS54/HP

Either way here are the fan table names and how it works

Thanks, this is a great explanation! Figured TunerPro and these XDFs was my next stop.

I didn't mean that the z4m uses the same DME setup, just that it has one electric puller fan, same as this mod. I figured I could copy the BMW-sanctioned fan curve and get appropriate fan speeds without experimentation. I know the MSS54 binary tool has a checkbox for z4m fan curve values, but I permanently lost the license to that software in a reformat and don't feel like paying for it again when a hex editor, tunerpro and these excellent XDFs can get the job done. Either way I think I can easily set a good fan curve based on this info without having to copy the Z4m.

[R3Z3N]

The Z4M did not use the MSS54/HP

Either way here are the fan table names and how it works

[repoman89]

Hey all, I’m going to be doing the Spal electric fan conversion soon using the aux fan controller. I know many of you have done the same and use the Z4M fan curve since it essentially has this setup. Anyone have the location in the binary of this curve as well as the Z4M values?