chronism

'07 GT
Steeda CAI & SCT X-Cal 2 Custome Tune

My issue is the cooling fan runs on high speed all the time once the motor gets to temp. I know that the tune has fan speed adjustments, but the tuner said he didn't want to mess with the defalts and risk overheating the engine. Is this somthing I should be worried about, the fan running all the time or is that normal?

281GT

There is absolutely no point in running the fan at all times. It will draw extra hp by working the alternator uneccesarily and wear out the fan prematurely. I did some research on this and I have found that many aftermarket canned tunes do this basing it on the assumption that the computer will shut the fan off at speeds over 40 mph. This is NOT correct. These cars have no provision to shut the fan off at speeds over 40 mph.
It would be a good idea if the car would do this as there is enough natural airflow through the radiator that a fan is not needed over 40 mph.
Fortunately there is an easy fix for this.
Just use your SCT to adjust the fan on / off temps in your tune. Keep the factory spread between the on / off points but bring the temps up to reasonable levels. The exact settings will vary depending on the average temp where you live.
Here are some settings you can try. If you find these settings are not quite right for you, you can try adjusting them all by the same amount a degree ot two at a time and then testing again until you have it right.

FAN HIGH SPEED ETC1 ON 207
FAN HIGH SPEED ETC2 ON 207
FAN HIGH SPEED ECT OFF 199
FAN LOW SPEED ECT OFF 192
FAN LOW SPEED ECT ON 193

I connected an LED in series with a 1k ohm resistor to my fan and mounted it inside my car so I know exactly when it is on or off. This also tells me when the AC compressor is running. You might wish to do the same as it makes knowing what's going on with your fan easier.

Good luck!

chronism

Thanks for the response and great info! Unfortantly, I don't have those parameters listed in my tuner, but I think the dyno shop has access, but they are uncomfortable adjusting them. Another question, would changing them affect the way the car runs or the tune itself?

GstangT

I've also heard about removing the cooling fan and fuel pump fuses when installing a tune. Not sure if it really matters though. But that might have something to do with it..

06GT4RAD

If you have the SCT X Cal II then you have the choice to go in and change these settings yourself. Also who's Custome Tune are you running?

Richard

281GT

The deal with removing the fuel pump and fan fuses fuse is only while you are loading the tune. The SCT tuning device is basically a dedicated computer and requires a stable power supply. By removing the electrical load of the fuel pump while you are loading the tune you are making sure that the tuning device has a stable supply of electrical power. Same deal with the fan fuse. SCT just doesn't want the fan turning on while the device is loading a tune as the sudden voltage drop could create a problem.

In response to the original poster. Changing the fan on / off temps will not effect the tune at all. It will have an indirect effect on how the car runs at times. For example having the fan running when it doesn't need to run will only cause the alternator to work harder which in turn takes power from the engine. Also there is a benifit to having the fan come on at a lower temp than stock. Anything that helps the engine run cooler has the potential to increase power via cooler air flowing through the air intake, cooler air = more dense air = more power.
The settings I posted appear in my Diablosport Predator. I wasn't sure how much different they are in the SCT unit but if your tuning guy adjusts for the same values it will have the same effect.

chronism

OK, Thanks. I don't remember seeing those options to change, just the shift pressure, tire revs, and some other stuff. I think the dyno-tuner guy has to unlock the other options for me to be able to adjust. My tune was done by a local Mustang performance shop, Performance Autosport. Great people to work with. I had a problem where my car overheated because of a bad fan relay and he didn't want to take a chance changing the fan options from the base tune.

So, leaving it alone and allowing the high speed fan to run all the time, will that wear out my alternator or fan motor? I would think that if you have enough airflow going 40+, then it would cool down enough to make setpoint and shut off the fan anyways?

281GT

It won't hurt the alternator at all. It's just that having the fan run at times where it isn't needed will only place a higher electrical load on the alternator which in turn will place more drag on the engine and suck extra horsepower and who needs that?
You are correct in that if the settings are adjusted correctly the fan should never come on at speeds over 40 anyway. The problem with many tunes is that they set the fans to come on at a temp BELOW where the thermostat opens so once the engine comes up to full operating temp the fan just comes on and stays on no matter how much air is moving through the rad because at that point the thermostat is the only regulator. Hope that makes sense.