Two questions - fan settings and tow tune

[techntrek]

Tried my new i2 today on my 2010 Suburban, stock engine, stock tune.

Went to advanced and expected to see a tow tune (the last tuner I owned had one). I do see the Diablo tune, which from what I've read here is the performance 91+ tune so I could use that instead. Maybe there is one in the easy tunes section, but I didn't poke around in there before I unplugged the tuner.

Fan settings, the biggest reason I bought this tuner. I tow a lot and I hate seeing the engine/radiator/oil temps fluctuate so much when it obviously the fans could keep the temps lower (I use an Aeroforce Interceptor to monitor oil, radiator, tranny slip, spark advance, etc while towing). So, why percentages for each setting, and why over a dozen temperatures? There are only technically 3 fan speeds possible with the series/parallel wiring and really only two get used, both fans on low and both on high. That only leaves two temperature turn-on points: turn fans on low at X and turn on fans on high at Y.

That said, what percentages correspond to low and high? The factory settings are incremented almost one percentage each (40 to 49%) between 192 and 214 F. Then it jumps to 55% at 221, 60% at 225, then 80, 90, 95 for 228, 231, and 235 F. Values above 95 appear to be possible. When towing I've always seen the engine temp slowly raise from 210 and 235, then I assume the fan turns on high which quickly brings it back to 210 (but the radiator temp goes down to around 286, then quickly rises back to 210 and the cycle begins again). So is low below 49 and high 95?

[06MonteSS]

no separate towing tune is needed.. the preset tunes are good for towing too.. no reason to have a towing specific tune..

on 2007 and newer vehicles, there is no fan temp setting.. you can not change the temps at which the fans operate, since they are electronic fans - you can only change the percentage of power that they run at.. i.e. 20% power, 50% power, etc... whatever you set them too..

the fan power is already increased in the preset tunes to have the fans run at more power compared to stock.

[techntrek]

no separate towing tune is needed.. the preset tunes are good for towing too.. no reason to have a towing specific tune..

on 2007 and newer vehicles, there is no fan temp setting.. you can not change the temps at which the fans operate, since they are electronic fans - you can only change the percentage of power that they run at.. i.e. 20% power, 50% power, etc... whatever you set them too..

the fan power is already increased in the preset tunes to have the fans run at more power compared to stock.

Thanks for your input. Since I tow with high octane gas I'll try the "Diablo" tune for 91 octane (or lower, based on what I've read here). I'll actually be pulling my 6000 pound camper this weekend for a trip. Going to be cold.

As for your answer on the fans, I've seen that same answer posted here before but it doesn't address the problem. I've read elsewhere that the newest Chevys (2014+) are PWM modulated so they should be set with percentages. They can go from 0 to 100.

Older Chevys (2004+ if I remember right, and 1999-2003 can be converted to this system) are driven by 3 relays which switch the fans between series and parallel wiring. So they can either run 2 on low, 1 on high, or 2 on high. In reality most years (2005 may be an exception) only run 2 low and 2 high which is why the percentages don't make sense. You can't "change the percentage of power that they run at". They are either off, low or high.

Since percentages is all that I can adjust on this tuner, there must be a cutoff in the numbers where below some number is low and above some number is high. Based on my observations while towing that the temps don't go down until they hit 235, 95% must turn on the high speed, but I'm looking for confirmation.

[techntrek]

So nobody has an answer? There has to be some percentage range for low and another for high.

[techntrek]

Great customer service for a product I just spent hundreds on. A simple question and no answer after a week.

[mikel]

there is no low/high speed to my understanding, you are setting the % of fan power to determine fan speed.

Thanks

[06MonteSS]

yeah, as I stated before, 2007 and newer vehicles is just a fan power percentage.. there is no high/low, and no temp changes..

just adjust the fan power % that you want them to run at, at the given temps..

[techntrek]

Mike, the fans are driven by three relays on the fuse block under the hood. Depending on which relays are grounded by the computer you either get "low" or "high". Edit: See my example below on what I should see.

06Monte, I don't know what you mean by "no temp changes". That is something I just proved you can do as I'll describe in the next post.

Edit: I'll give an example of how the settings should appear in the programmer for my truck. Note the use of "off, low, high" instead of percentages.

192 off
to
214 off
221 low
225 low
228 low
231 high
235 high

[techntrek]

For future reference for those that search for this info, I'll document my test results here. I will need to rig up lights connected to the fan relays so I can see which speed - low or high - comes on and when, and then try different percentages to see which ones trigger the two speeds. Until then I can try one thing first...

My primary goal is to prevent my engine temperature from rising to 235 while towing. At that point the fans come on high and the temperature quickly drops to 210, while the radiator temperature drops to 185, then it quickly rises back to 210 then slowly rises to 235 when it starts all over again. Meanwhile the oil temperature skyrockets. After checking out multiple GM/Chevy forums this appears to be normal - engine and oil temps.

So I ran my first experiment today since I'm on a camping trip this weekend (I do one winter trip each year). I kept the stock tune for now since I only wanted to see what messing with the fan settings would do. This is what the i2 shows for my truck as stock:

Between 192 and 214 F, each % setting rises by one (except one). 40% @ 192 F to 49% @ 214. Then 55% @ 221, 60% @ 225, 80% @ 228, 90% @ 231, 95 @ 235 F.

For the 2 hour trip out I changed every setting starting at 214 (might have been 217) all the way up to 235, making every one 95%. I KNOW the fans aren't coming on high until it hits 235 so it is likely it has to be set 95% or higher to trigger the high speed. I left the lower temperature settings at stock. As desired, and amazingly, for the first time ever, the engine temperature never moved off of 210 F! The radiator temp stayed between 190 and 195, and as a result of the cooler engine my oil temps stayed between 217 and 226 instead of climbing to 265. BINGO! That is the final result I wanted.

Now, I've read that the performance tune has different fan settings than stock to help manage temps better. So for the trip home on Sunday I'm going to apply the performance tune, overwriting the settings I made for the trip out, and I'll report back how that affected things.

[techntrek]

I didn't quite get the get the test I wanted coming back home today. I went to Advanced and installed the Diablo tune. I expected it to prompt me about the altered fan settings but it didn't. It wrote the tune, and when it was over I rebooted and went back in to check the fan settings. The asterisk was next to the Fan Settings option and sure enough the changes I made were still there. I tweaked the 214 setting to 75 just to see if I would see anything different on the way home and wrote the tune again. I didn't have time to figure out how to get the Diablo fan settings.

A noticeable increase in throttle feel with the new tune, and the same results with the engine temps as before - never budged off of 210 and the radiator held around 190, oil never went above mid-220's. This will likely be what I stick with long-term for towing although I may try firmer shifts. Not sure yet about daily driving, I will probably try other tunes for that but since I've read you can run 87 octane with the Diablo tune I may just leave it alone.

As for testing to figure out which percentages trigger which fan speeds, I still want to figure that out. Need to add those lights first.

[06MonteSS]

Need to use at least 91 octane with the Diablo Tune... It has higher timing settings made for at least 91 octane.. Don't use 87/89 on the Diablo Tune.

[techntrek]

I must have misread that, then. Only problem with that for towing is at higher elevations higher octane isn't available.

So then if I use the 87 or 91 tune, how do I force the i2 to revert to the fan settings that are part of either tune so I can test them?

[techntrek]

Installed the 87 tune and this time when I went to install the tune it prompted me about the altered fan settings. Didn't do that when I installed the Diablo tune.

[techntrek]

I did another 2 hour tow this weekend and had the same results, with the outside temps at 60 F on the way out. Definitely happy with this change with a 40 degree drop in oil temp - and corresponding increase in oil pressure which was my ultimate goal. I can't understand why GM lets the oil get heat soaked when a minor programming change prevents it.

I also tried the firm shift and didn't notice any difference most of the time, but at WOT it shifted too hard for my comfort. Going back to the factory soft shift tranny tune.