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DFI and ECMDiscuss all aspects of DFI (Digital Fuel Injection), ECMs (Electronic Control Module), scanners, and diagnostic equipment. Fine tune your Third Gen computer system for top performance.
Hey guys this is geared towards the Holley efi guys but I'm just looking to see if I've got this configured right. I want to turn engine fans off at highway speeds. I followed this post: https://forums.holley.com/forum/holl...egy#post377114. I made a "Master Fans" custom Output in the I/O ICF then linked that to "Electric Fans" Output where I've got configured as: RPM -> Above 500 (fans off key on engine off.) CTS -> Above 185°F Deactivate 175°F. Speed -> Below 65 MPH (I'm in Canada so that roughly 95 km/h.) Does all this look right or have I missed something? Thanks everybody for the input always appreciated
I know the two conditions I've got for RPM (key on engine off) and CTS work as they should I'm still kinda wondering about the Speed condition. The way I'm understanding it is that the fans will run when my speed is BELOW 65 mph(104 kmh) which is exactly what I want. I did try asking over on Holley forums but they linked me to a thread that had nothing to do with what I wanted to achieve. I'll post up some screenshots of how it's set up in the software.
I don't understand Danny's explanation either. Seems your Master Fans output will just mimic the Electric Fan output and not add any value. Your Electric Fan output, as written, will do what you described but it lacks a CTS high-temp override to turn on the fans no matter what. I might try something like this....
1. Assign the Electric Fan output to a (+12V) custom output, and wire it to the high side of the fan relay field coil. Configure it using the RPM and CTS conditions you made.
2. Assign the Master Fans output to a (Ground) custom output, and wire it to the low side of the fan relay field coil. When this output is deactivated, it will disconnect the relay coil circuit. When this output is activated, it will ground the relay coil thereby completing the circuit.
Activate when: (MPH < 60) OR (CTS > 195)
Secondary deactivation: (MPH > 65)
There is no need for a CTS secondary deactivation because the Electric Fan config takes care of that.
Basically your Electric Fan config handles all your AND logic statements, and the Master Fans config handles all your OR statements. You can add more logics for A/C compressor or whatever you want.
A note worth adding is if the MPH activation and deactivation are too close to each other, then the fan relay will flutter on/off in that range of cruising speed. That's why I put a 5 mph spread between the two. It's not perfect but that's the reason why.
And if you're cruising at 65 mph and slow down below 60 mph and then speed up again to 65 mph, then your fan might cycle on/off if the temp is somewhere between 185-195F. If you're concerned about that possibly causing extra wear and tear on your fan motor, then make both temp thresholds the same.
I have 2 fans on my car. One of them I always run with A/C (monitors the switch position in the dash). The cool thing about that is I can run the fan with the engine off when parked at the track. All I do is turn key to RUN position, and slide my HVAC controls into the A/C position and the fan will turn on. Slide HVAC out of A/C position and fan turns off because (engine RPM = 0) which is below the fan enablement threshold.
Just a neat little trick you might be able to use.
I don't understand Danny's explanation either. Seems your Master Fans output will just mimic the Electric Fan output and not add any value. Your Electric Fan output, as written, will do what you described but it lacks a CTS high-temp override to turn on the fans no matter what. I might try something like this....
1. Assign the Electric Fan output to a (+12V) custom output, and wire it to the high side of the fan relay field coil. Configure it using the RPM and CTS conditions you made.
2. Assign the Master Fans output to a (Ground) custom output, and wire it to the low side of the fan relay field coil. When this output is deactivated, it will disconnect the relay coil circuit. When this output is activated, it will ground the relay coil thereby completing the circuit.
Activate when: (MPH < 60) OR (CTS > 195)
Secondary deactivation: (MPH > 65)
There is no need for a CTS secondary deactivation because the Electric Fan config takes care of that.
Basically your Electric Fan config handles all your AND logic statements, and the Master Fans config handles all your OR statements. You can add more logics for A/C compressor or whatever you want.
Thank you sir! This makes much more sense than what Danny was saying. I'll make some changes when I get the chance. Temperatures suddenly dropped and it's starting to snow!! And apparently I'm flying out to work Monday. Hahaha
A note worth adding is if the MPH activation and deactivation are too close to each other, then the fan relay will flutter on/off in that range of cruising speed. That's why I put a 5 mph spread between the two. It's not perfect but that's the reason why.
And if you're cruising at 65 mph and slow down below 60 mph and then speed up again to 65 mph, then your fan might cycle on/off if the temp is somewhere between 185-195F. If you're concerned about that possibly causing extra wear and tear on your fan motor, then make both temp thresholds the same.
Ah yes good point maybe a higher speed point would be better
Originally Posted by QwkTrip
Also, your fan deactivation temp setting might be too low and result in the fan never turning off, but you can fine tune it after some data logging.
I do have a 160* thermostat in the car and in the summer those fans never really shut off. But I have pulled my turbo hot side off and sent them in to get Cerakoted glacier black with the hopes it brings under hood temps down somewhat. Summer time where I live it gets bloody hot. I'll definitely be data logging
Does any of this function somewhat mimic the factory fan function? I am curious as to whether the factory fans turn off above a set road speed. I have searched but could never confirm if the factory fans turn off or not.
I am curious as to whether the factory fans turn off above a set road speed. I have searched but could never confirm if the factory fans turn off or not.
Some don't, some do, depends upon the ECM and the implementation.
02-16-2024, 05:51 PM
