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Fans always on? Good or bad idea

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rtrocket59

10+ Year Contributor
202
1
Jul 8, 2011
Rockaway, New_Jersey
My 2g runs at 205° according to my dsmlink. I replaced the fans, radiator, thermostat (mishimoto 160°) and hoses and she still runs hot. I activated the fans always on through dsmlink and now it runs between 180-160° (traffic and idle). Would keeping them on be smart?
 
205 is normal. Fans are usually set to come on around 210*. Why are you running a low temp thermostat? It doesnt help with cooling/overheating any better then stock. If you are worried about your coolant temp, set link to throw a CEL at 217-220* to see if it gets higher then the stock fan settings. Running such a low thermostat can play hell with fuel trims and take the car longer to get into closed loop.
Fans are only good for idle conditions and do nothing while driving. If you dont need them on all the time then keep them on the stock settings. If you overheat then you have bigger problems to worry anout.
 
I have both my fans wired to a switch. I wind up leaving them both on all the time. As long as its not covering up a problem in your cooling system then its okay to leave them on.
 
You'll be fine leaving them on - I have the fan mod where they both come on at the same time. What's your concern in terms of leaving them on?
 
205 is normal. Fans are usually set to come on around 210*. Why are you running a low temp thermostat? It doesnt help with cooling/overheating any better then stock. If you are worried about your coolant temp, set link to throw a CEL at 217-220* to see if it gets higher then the stock fan settings. Running such a low thermostat can play hell with fuel trims and take the car longer to get into closed loop.
Fans are only good for idle conditions and do nothing while driving. If you dont need them on all the time then keep them on the stock settings. If you overheat then you have bigger problems to worry anout.

I'm using a low temp thermostat because I wanted the car to run cooler but it clearly didn't do much. How does it effect the fuel trims?

TopGun8818 said:
You'll be fine leaving them on - I have the fan mod where they both come on at the same time. What's your concern in terms of leaving them on?
I heard leaving them on could cause damage to the fan. Didn't really believe this but I wanted to double check on here.
 
205 is normal. Fans are usually set to come on around 210*. Why are you running a low temp thermostat? It doesnt help with cooling/overheating any better then stock. If you are worried about your coolant temp, set link to throw a CEL at 217-220* to see if it gets higher then the stock fan settings. Running such a low thermostat can play hell with fuel trims and take the car longer to get into closed loop.
Fans are only good for idle conditions and do nothing while driving. If you dont need them on all the time then keep them on the stock settings. If you overheat then you have bigger problems to worry anout.

Listen to the man.Having fans on all the time is only going to put an unnecessary drain on the battery/charging system. One reason engines and many other pieces of machinery for that matter operate just over the 200* mark is to evaporate moisture that forms inside them.Moisture causes rust/corrosion..we no like that kind.:thumb:
And if i remember correctly the fuel trims will not show change until the coolant temp is above 186?or something around there
 
LiquidX said:
Actually it helps out greatly if you are at a low enough t stat. The 180* stock pieces is fully open in the high 200* range, well above where I want my temps. The 170* is fully open around 190* range cooling off more coolant before it gets too hot.

And you are right, for most people with a FMIC it will be useless as they aren't efficiently directing airflow to the radiator so it won't matter as the radiator isn't getting cooled off as it should. For those of us that do, it does help out as I've even had it help me out.

I personally would even run 160* if one was available for a 2g and not just the 1g. This of course would be ran in the summer and I would still hit 180* coolant temps. If I was off by a little then just use the coolant offset and everything will be where it should.

There isn't a real reason why you shouldn't run a colder t stat as long as you can monitor the temps and be sure of where they are at so you can compensate for it IF needed.

Seems like running a colder thermostat really isn't a bad idea. I'm going to deactivate the fan always on control and just offset the coolant temp by 15* to have the fans go on at 190* rather than when they come on at 206*
 
I would much rather replace an alternator which comes with a warranty then having to rebuild/replace a head due to it overheating. I take that this is a temporary fix and not permanent solution correct? I too had really bad overheating issues and have replaced and added pretty everything to help the car run cooler (mishimoto aluminum rad w/electric fan kit, water wetter, low temp thermostat, fans re-wired etc.) It greatly helped but I still experience overheating when the weather reaches 95* plus here in California. However, I usually put the heat on full blast and roll the windows down which grealty helps. Search overheating issues and you will be provided with a ton of usefull information to further assist you.
 
I'm going to deactivate the fan always on control and just offset the coolant temp by 15* to have the fans go on at 190* rather than when they come on at 206*

The only thing about this is that the ecu will pull a degree of timing at (a perceived) 206*. To counter this, you can globally raise timing, which, in my opinion, is a sloppy workaround. I really don't see why ecmtuning won't incorporate a custom parameter fan control function based on coolant temp, and this is really the only complaint I have with link.

In my case, if I leave the fans full on, my temps drop to about 160*. If I leave it up to the ecu, I'll see upwards of 220*...it's dangerous to keep activating and deactivating the fans while trying to drive. More reason to incorporate fan control.
 
Well heres a no brainer(myself included)Any heat shielding/wrap on the manifold,turbocharger,or downpipe?If not covering those items with something will immensely help from baking the radiatior,block,and head.

Great note. Include myself on this. Over this winter I'm going to have some kind of heatshield fabbed up around the exhaust manifold as my GSX needs all the help it can get with dropping the temp.
 
Well heres a no brainer(myself included)Any heat shielding/wrap on the manifold,turbocharger,or downpipe?If not covering those items with something will immensely help from baking the radiatior,block,and head.

I am replacing all of those components soon but I definitely will once the build is completed.
 
I am having a hard time believe that dsms are not supposed to run at 206.

Can anybody cite an FSM that states timing is pulled at 206+ or cite the ECU code that states this, or is it more dsm myth?
 
2g's pull timing at 206*
important2gcoolantpoints [ECMTuning - wiki]

not sure if 1g's do the same, but one would think so...

Thanks for the info.

No, it's not the same for 1g's.

Quoted from a conversation I had with an individual who works with the coding of 1g ecu's:

"and there you have it
it doens't even pull 1 degree
it actually adds timing when its cold
and goes to a 0 when its warm

Code:
13755  FE98             ;****************************************************************
13756  FE98             ;
13757  FE98             ; Interpolated from ect, used in timing advance calculations
13758  FE98             ;
13759  FE98             ;       $81 =  1 deg advance
13760  FE98             ;       $80 =  0 deg
13761  FE98             ;       $7f = -1 deg advance
13762  FE98             ;
13763  FE98             ;****************************************************************
13764  FE98 80 80 80 80 L2020       .byte   $80, $80, $80, $80, $80, $84, $88, $8b      
13764  FE9C 80 84 88 8B[code]

$80 is the focal point of 0

 anything higher is +
anything lower is -
its hex for 128
the only time timing is retarded is based on the IAT
NOT the ect"
 
Well, all the post are good, but I never see any one mention about air duct.

Making a nice air duct will help tons, and will run colder, now the low temperature thermostat will help but not much, unless you have a good air duct, if you don't have it, then that thermostat will not help as it should, because once the thermostat opens, the fans will not be ON and will not be able to cool it down as it should, it will cool only by the air that is coming from the front.

Just Off set in link and play with it, if you see getting kind of hot, then adjust the off set a little more and you should be OK.
 
My cars runs at the same temperature and it has never given me a problem. When I'm in the city I like to have both fans turned on since it get real hot here in Florida. But if I'm on the freeway I let one fan do its job. Heat shields and wrapping really help, and if you want to go crazy you can always fabricate some custom air ducts.
 
If you deleted your A/C system, you can use the A/C switch to turn on both fans.

Or wire the relays together. Literally takes 1 wire and 10 minutes, at least on the 2g.
 
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