Speeduino

Pwm signal either directly to the fan(s) or to the oem controller eg
The jaguar/ford fan controller drive signal
COOLING FAN MODULE CONTROL: PWM, 140 Hz, POSITIVE DUTY CYCLE RANGE 7% – 95%

Probably a simple lookup table against engine temp?

How would you look to drive the fan? The boards outputs are intended to control a relay, not the fan directly. PWM won't work with the relay, so you'd need an offboard high current driver.

The ford/jag module connects to up to two fans(brush motor type) and takes the low current pwm signal from the ecu to drive it @140hz ,7-95% output
Really needs a similar setup to what you did with the vvt , but with just water temp on the table axis perhaps?

Bmw uses external power module driven by pwm.

noisymime wrote:How would you look to drive the fan? The boards outputs are intended to control a relay, not the fan directly. PWM won't work with the relay, so you'd need an offboard high current driver.

Glad you mentioned that, you actually beat me to the punchline.

We manufacture and maintain stock of a small module that takes care of this, very popular with the aftermarket ECU crowd.

Enclosed are schematics and so on, very compact and very easy to make it work with the same I/O output at different speeds.

I could see this as a positive thing for water-cooled motorcycles and other vehicles with constrained charging systems.
I know, at least on my bike, when the fan kicks in there's a significant draw on the system because the headlight dims. Being able to control the fan speed could reduce the current draw substantially when full fan speed isn't required to keep up with cooling needs.

One issue I see, though, is the thermostat is there to regulate engine temps so the cooling system fan requirements aren't directly correlated to engine temp- when the t-stat opens the temperature of the coolant might be anywhere from the stat's opening temp to over 100C but nominal airflow across the radiator might be enough to cool things down, so to speak. So, a second temperature sensor might be needed to measure the coolant temperature leaving the radiator. Then the system could calculate the temperature drop between the two and control the fan speed based on that. Might even want a purely ambient air temp sensor as well that could bias things- make the fan more likely to run or run faster when ambient air temps are higher....

Yeah, I think too much.

We have the same need for fuel rail pressure control on a diesel engine
we need pwm with a similar frequency

As per my experience is the thermostat is there to regulate engine temps so the cooling system fan requirements aren't directly correlated to engine temp- when the t-stat opens the temperature of the coolant might be anywhere from the stat's opening temp to over 100C but nominal airflow across the radiator might be enough to cool things down.
So, a second temperature sensor might be needed to measure the coolant temperature leaving the radiator. Then the system could calculate the temperature drop between the two and control the fan speed based on that.

NanFein wrote:As per my experience is the thermostat is there to regulate engine temps so the cooling system fan requirements aren't directly correlated to engine temp- when the t-stat opens the temperature of the coolant might be anywhere from the stat's opening temp to over 100C but nominal airflow across the radiator might be enough to cool things down.
So, a second temperature sensor might be needed to measure the coolant temperature leaving the radiator. Then the system could calculate the temperature drop between the two and control the fan speed based on that.

Why are you using cx500tc's words? Failed quote?

cx500tc wrote:I could see this as a positive thing for water-cooled motorcycles and other vehicles with constrained charging systems.
I know, at least on my bike, when the fan kicks in there's a significant draw on the system because the headlight dims. Being able to control the fan speed could reduce the current draw substantially when full fan speed isn't required to keep up with cooling needs.

One issue I see, though, is the thermostat is there to regulate engine temps so the cooling system fan requirements aren't directly correlated to engine temp- when the t-stat opens the temperature of the coolant might be anywhere from the stat's opening temp to over 100C but nominal airflow across the radiator might be enough to cool things down, so to speak. So, a second temperature sensor might be needed to measure the coolant temperature leaving the radiator. Then the system could calculate the temperature drop between the two and control the fan speed based on that. Might even want a purely ambient air temp sensor as well that could bias things- make the fan more likely to run or run faster when ambient air temps are higher....

Yeah, I think too much.

Mentioned above schematic and photo of compete unit were stolen by Juan Blanco from my site:
http://secu-3.org/documentation
Juan, it is not good to edit pictures...