PCM/Fan/Temp Question

[SRT-IZ]

I have a stage II PCM from BG in my truck and as most of you know i have been conserned about the temp on my truck. I installed a 170 thermostat and ran at about 205* or so. I was still not happy since the temps here are starting to creep up (101 yesterday) and i want to keep the truck cooler. I took out the 170 and installed a 160. It seems to do a little better, now the temp will stay slightly under 200.

My question is, by having the Stage II, should the fan be running all of the time? No matter what the engine temp is?

Thanks!

 

[SANCHOBA]

i don't know....ive' been told once the temperature gets up in the 90s' a lower temp thermostat doesn't do any good:dontknow:

 

[jrangel]

It was 97 degrees here in SO Cal yesterday my truck with AC temp was 180. Oil and water. I have the 172 and DC Stage II flash.

 

[LoveThisTruck]

Mine will stay between 170-180 as long as I'm moving. Stop and go it stays around 190-195

 

[SRT-IZ]

Yes but should the fan be running all the time or only at a certain temp will it kick on? (remember StageII)

 

[moparracing]

i think the hydrualic fan is setup for @ least two speeds....... the low speed runs pretty much all the time..... you'd know if it was running in high speed - loud as hell.....

mine runs @ the same temps as "LoveThisTruck" in low speed...... when marty first set my fan speeds for my sct, it ran 170 all the time, but the high speed fan was on alot @ stop lights & it is loud... had people lookin' @ me for the wrong reasons....... so, i had marty change the fan speed temps to what they are today & no - i don't remember what they are....

that is what's nice about the sct tuning, it's a small email file that your tuner can send you changes & you can load them yourself......:rock:

 

[FastRam]

I am not sure on the trucks but the 6.1L's will run all the time if the T-stat and PCM are not coordinated with each other. I recall as well the 6.1's had nine different fan turn on temp settings for low/medium/high fan speeds. I am not sure if the 8.3L uses the same strategies to control fan speed and temp control. I would contact B&G and ask them the question but IMO the fan shouldn't be running all the time. Also, engine temps in the 200 - 210 range are OK for a stocker 8.3L.

 

[SRT-IZ]

Well if it is as loud like you guys say then i dont think my fan turns on or goes to high speed at all. I never hear it and no matter how cool or how hot it is outside the truck runs at 200*.

Is there a way to check and see if it goed to high speed?

 

[SANCHOBA]

I never hear it and no matter how cool or how hot it is outside the truck runs at 200*.

when its cool out side my temps drop,but right now in this 85-90 degree weather its pretty much always at 200*


come to think of it... ive' never HEARD my fan either:dontknow:

 

[GILMO'S10]

dc seems to have the fan come on sooner.I have a B&G also and wish it came on sooner.This topic has been discussed many times on this site and the general consensus is 200 is about right for these trucks.I put the 170 t stat in mine and it really did not make alot of diff.I stopped giving a chit and moved on.

 

[JTS VENOM PERFORMANCE]

IZ, your computer has not been modified to have the fan come on sooner, as with you Gilmo,

When having one flashed by BG you need to telll them the certain items you want, such as the fan comming on earlier.

no matter how low a thermostate you put in , it will still run around the 200 mark untill you have the pcm flashed for the fan to come on earlier.

somewhere there is a thread about installing a manual switch.

but the flash I had from BG had the fan come on around 175, and it never ran over 180, even with the turbos in extremely hot temps

 

[SRT-IZ]

dc seems to have the fan come on sooner.I have a B&G also and wish it came on sooner.This topic has been discussed many times on this site and the general consensus is 200 is about right for these trucks.I put the 170 t stat in mine and it really did not make alot of diff.I stopped giving a chit and moved on.

This is kinda what i wanted to hear. I just didnt want to be the only one and have it in my head that there is something wrong. Im still goint to try and do something to make it cooler. I dont know what yet tho.

 

[GILMO'S10]

IZ, your computer has not been modified to have the fan come on sooner, as with you Gilmo,

When having one flashed by BG you need to telll them the certain items you want, such as the fan comming on earlier.

no matter how low a thermostate you put in , it will still run around the 200 mark untill you have the pcm flashed for the fan to come on earlier.

somewhere there is a thread about installing a manual switch.

but the flash I had from BG had the fan come on around 175, and it never ran over 180, even with the turbos in extremely hot temps

that what i get for buying it from Boomer!! can u send it off and get it fixed?

 

[SRT-IZ]

IZ, your computer has not been modified to have the fan come on sooner, as with you Gilmo,

When having one flashed by BG you need to telll them the certain items you want, such as the fan comming on earlier.

no matter how low a thermostate you put in , it will still run around the 200 mark untill you have the pcm flashed for the fan to come on earlier.

somewhere there is a thread about installing a manual switch.

but the flash I had from BG had the fan come on around 175, and it never ran over 180, even with the turbos in extremely hot temps

Cool...so where are these instructions?

 

[SRT-IZ]

can u send it off and get it fixed?

:dito:

 

[JTS VENOM PERFORMANCE]

that what i get for buying it from Boomer!! can u send it off and get it fixed?

yes, now I dont know how much, but you would have to contact BG again , but they may charge youthe same amount as a complete flash , not really sure,

but i would call them and ask if you could send it in , and jsut get the fan turned on at a lower temp

 

[JTS VENOM PERFORMANCE]

Cool...so where are these instructions?

not really sure Iz i think it was stingray that posted them up, but not sure:dontknow:

 

[SRT-IZ]

Just spoke with BG. He said that the fan on the trucks turn on at 226* stock and that the flash does turn them on sooner. He also said that the temp should be at around 200* with the flash which is what mine is. So with that being said my head is a little bit more at ease. I would still like to find out those instructions.

 

[JTS VENOM PERFORMANCE]

Just spoke with BG. He said that the fan on the trucks turn on at 226* stock and that the flash does turn them on sooner. He also said that the temp should be at around 200* with the flash which is what mine is. So with that being said my head is a little bit more at ease. I would still like to find out those instructions.

not sure what the dif is then:dontknow: mine never went over 180, but let me see if I can find them for ya

 

[JTS VENOM PERFORMANCE]

Manually turn on your stock cooling fan

--------------------------------------------------------------------------------

Ok, I’ve had a few people asking me about modifying their stock cooling fan to turn on sooner. There are a few ways – custom flash from DC or Boomer to have the fan turn on sooner (that’s the best way) – adding an auxiliary electric fan (I tried a dual fan and it still would not keep the temps cool enough) – or wiring in some relays to turn the fan on manually (the method below).

Edit – If anybody is going to attempt this I want you to be aware of some potential issues. Basically, do this mod at your own risk. You do not want to race or ‘hammer down’ with the fan turned on high. The power steering pump will be working hard to drive the fan and it will not like high RPM’s at the same time. You will also be heating up the power steering fluid a little more than normal too, so I wouldn’t run the fan all the time, only when needed to bring the temps down. There is no long term testing of this setup. I had it on my truck for only a couple months before I sold it and I have not heard back from the new owner. While I had this mod, I had no issues though.

I also attached a new schematic further down for a simple manual on/off switch control of the fan.

What I came up with was the last one . But let me throw out some notices first. The fan will only turn on at full speed, I can’t make it variable. When the fan is on full speed it’s quite loud but it moves a lot of air! The fan is driven by the power steering pump so at times when doing parking lot maneuvers you may notice the steering is a little more tuff to turn (but it’s not too bad). Will there be any long term affects on the fan or power steering pump, I don’t know?

There are a couple ways to wire up a manual override for the fan. The easiest would be to bypass the PCM but I would not recommend that because if anything should fail (like the relays or wiring) then the PCM cannot run the fan. To keep the PCM in the loop it gets a little more complicated but safer.

What’s needed are 2 diodes, a 20 to 1000 ohm resistor, and a way to supply a power and ground circuit either using a relay, switch or combination of the 2. I attached a cheesy schematic that I drew up showing what has to be done to the cooling fan harness. The cooling fan solenoid harness runs from the bottom of the fan assembly up and then across the passenger side of the radiator support by the air box. There are three wires in the loom – black, brown with white, and the one you want to splice into light blue with tan. I left the relays and switches out of the schematic because those can be wired up a few different ways with even more ways to trigger them. If you just want to manually turn on the fan with a switch, it needs to be a DPST – double pole single throw. 2 separate switches might not work because the power and ground that you need to supply to the fan harness has to be at the same time to fool the PCM. Otherwise a check engine light comes on with a P1499 code. If just a good old fashion single switch is going to be used then have that switch supply the power to the fan and also have it trigger a single relay that will supply the ground. A third way to trigger the fan is with 2 relays. On my truck I tried using an aux dual electric fan with a thermostat controlled relay. The fans could not keep up so I removed the fans but I kept the thermostat relay. That relay provides my battery voltage and also triggers the second relay that provides the ground. Most relays should come with their own schematics.

One other note, if the thermostat method is used then you will want to also install a manual override switch to disable the relays. Basically if you are racing the truck you don’t want that fan to be running. It robs HP and you don’t want the power steering pump to be working it’s azz off with the engine at 6k rpms!

This all may sound like it’s a pain in the ass, but it’s actually easy to install if you’ve done any wiring before.

If you have any questions don’t hesitate to ask me .


http://www.vtcoa.com/forums/showthread.php?t=1068&highlight=fan+manual


now IZ I know that Dave at BG dont like to turn them on too low , so you have to be a little firm with him and tell him exactly what you want.

I know Chris at DC will turn them on at a lower temp, but BG you have to "tell' them you want it on lower