Does anyone know the reasoning behind the fact that when you turn on the running lights, the radiator fans kick in sooner? Ever since I installed a water temp gauge and saw how high "normal" temps are on this car I've taken to leaving the running lights on ALL the time.

 

The lights draw a higher electrical load which comes from the alternator. The alternator causes more load on the engine. More load, potentially more heat. Also notice that the idle increases when the computer senses the higher load. The temp at which the fans come on is programmed into the computer to compensate for the higher load. Switching to fan position 3 without air conditioning on also causes it to sense a higher electrical load, at least on my car.

 

Thanks for the explanation! I've never seen this behavior in any other car but then again, the FD isn't like any other car I guess. I can't imagine just having the running lights on draws so much more power that the motor generates an extra 10 degrees of water temp in heat output.

 

10 degrees is about right. I have a PFC so I know, at least on my car, that with no electrical load (ELD), the fans come on at 100degC, with ELD on they come on at 94degC.

100degC = 212deg F
94degC = 201.2deg F

 

Yes, my car runs about 10 degrees cooler with the lights on, however what i was saying is I don't think that just by turning on the parking lights the motor has to work hard enough that it generates that much more heat. Essentially I'm saying that this "feature", while it's nice to have and exploit, doesn't seem to really be necessary.

 

It is simply because there is a finite amount of adjustment in the system, the addition of the small amount of load is really like the metaphor the straw that broke the camels back I think.

That is one of the real benefits of the datalogit, user defined settings for things like water temp fan controls.

 

IIRC the reason is because the electrical load system kicks the fans on earlier when the lights are on. It doesn't actually measure the amperage on the alternator, or the heat being produced, it simply is programmed to kick them on earlier when the parking lights or headlights are on. Kind of a goofy system, but that's how it is.

I always drive with the parking lights on. A little better for safety, and it keeps the engine temps down better. That plus a 2nd gen thermoswitch is a pretty cheap way to keep cooler.

Dave

 

I just got through re-doing my coolant system electronics. I will put an accurate gage in later, but my fans weren't working at all.

I put in the FC thermoswitch, and a new thermosensor. Replaced a bad relay (#3 I think it was), and put in piggy-back relays on 3 of my 4 original relays.

The piggy-back relays activate 3 of the 4 relays (the 4th relay is pulled in, in parallel to the original #2 relay, so I guess you could say I am activating all 4 relays), in order to turn on the fans to HI speed. I put a switch on the center console in the blank between the fog light switch and rear defroster switch. Looks decent.

The way I have my piggy back relays wired, if I DO NOT flip my manual switch in the cab, the cooling system will work as originally designed. Meaning, when the fans should be on LO, they come on at LO. The cooling system mod in the stickies had it such that whatever setting the original design called for, the fans would actually run at one setting higher ... meaning no more LO fan. I just have a fixation for things to work as originally designed. If I want to throw it on HI, like when I know I'm about to create a bunch of heat or when I'll trolling slow through a parking lot, or shutting it down on the timer, I'll flip my switch and run HI speed fan. Works real smooth.

- Jason Oliver (a.k.a. JyRO)

 

Right, my saying the computer senses the electrical load in my post above is actually referring to the conditions that activate the ELD input to the computer, not the actual load or temperature itself. These conditions being parking lights on or interior fan on position 3 or 4. AC on may do the same, haven't tried it. If temps are an issue, I usually just turn the fans to postion 3.

 

You should do the fan mod and your fans will come on at around 83 C. Keeps the car running cool and calm.

 

if you have a power fc you can set the fans to come on at 180 and not have to worry about it any more

 

Why on earth would you set your fans to come on at 180??? Optimum running temp BEGINS at 180, and extends to 220. To start cooling the car FROM 180 means you're trying to drop the temps BELOW 180, keeping it OUT of optimum running temps. Cooler is NOT always better... only within optimal running temps.

~Ramy

 

my temp gauge stays right on at 180deg unless i drive it hard then it goes upto 190 or so but then it cools right back to 180 with no problems i also have a thermostat that opens at 180 so its perfect

 

i read about this mod earlier last year..(only had my car for 2 years) and i just replaced the gauges....i did notice a big difference when i ran her with and with out the running lights on. curious. well either way i like the results..

 

You'll also see the same results with the AC on and fan speed in lower settings as well as with the rear window defroster. Any of these conditions either causes the fans to come on and if there already on go to the next level of speed.