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EFI Tuning Fundamentals

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I am trying to figure out when my fan is switched on or off. They are wired to relays and their not variable speed. How is Fan state transition % related to Fan Desired % vs ECT?

So EX: At 192 degrees in Fan Desired is set to 45% the fans will turn on at 86 degrees? If my fans are not variable speed should my fans desired table be set to 100%? Note I have a 2 bar software.

What ECU and/or tuning software are you using?

Not quite sure what you're asking?

Is it how to set up PWM control for their speed, assuming they're compatible with this, and the relays will work with this - you will probably need to use solid state devices rather then the more conventional electro-magnetic type with actual mechanical contacts.

If it's how to set the temperature they come on and switch off at, there should be an "on" and an "off" setting for the fans - where they're set will depend on your specific application but you're probably going to be looking at 5C to 10C difference so they're not continually turning on and off. NOTE, you may also need to check and possible replace the current thermostat with a cooler one and/or have the switch temp's higher than you may expect - not much point turning the fans on if there isn't actually any coolant moving through the radiator.

David, ECM > E38 GM Gen4 V8. I have attached a screenshot of the tables I was referring to. Let me know if this helps or if you have any other questions.

Attached Files

OK, I don't know much about GM ECUs, but there seems to be some info over the HP Tuners board about this topic:

https://forum.hptuners.com/showthread.php?7621-LS2-Fan-Logic-or-lack-thereof&highlight=LS2%20fans

https://forum.hptuners.com/showthread.php?57207-Super-COOL-(sorry)-cooling-fan-control-discovery!

Thank you David for sharing these 2 links.