Cooling fans

[gtstorey]

So your temps are hitting 212 when the outside temp is 97, while running the ac, while probably driving in traffic, with a very large transmission cooler probably in front of the radiator? My vote is yes you are asking to much if you think the temps are going to be lower than that. Since the stock settings don't have the fan on high until it is in the 220's it is fine at 212.

[morepowerjoe]

Originally Posted by gtstorey

So your temps are hitting 212 when the outside temp is 97, while running the ac, while probably driving in traffic, with a very large transmission cooler probably in front of the radiator? My vote is yes you are asking to much if you think the temps are going to be lower than that. Since the stock settings don't have the fan on high until it is in the 220's it is fine at 212.

No I don't expect then to be lower I'm just wondering if running them at 85% all the time is too much for them. I guess that's the way to find out though. And yes that's idling in traffic with the ac on and a big old tranny cooler in front of the radiator. lol. When I'm moving it stays around 205*. Also I'm just wondering if 212* is acceptable for burning off contaminates in the oil?

[gtstorey]

Are you think the fans are like injectors and should be ran less than a certain percentage or you will cause them to fail? I don't think the fans work like that, and in fact I don't think our fans are PWM but are instead "discreet" which mean the percent fan speed doesn't mean much that the fans are off at 0%, both fans on a low at 50%, one fan on low & one on high at 75% and both on high at 100% or something similar. I don't know the actual percentages that relates to the various fan speeds, but I think this is the control scheme.
I'm also not sure how it interpolates between these percentages. It may just go up to the next fan setting as soon as it goes above 50% or 50% may be a range that extends to 62%. But at some point your 85% is either running 1 fan on high and 1 on low or both fans are on high. Neither is running at 85%.

At some point the fans only have so many rotations in there, but I wouldn't worry about some percent of running being to much and then a little less meaning a lot longer life.

[NOT A 45]

Originally Posted by morepowerjoe

No I don't expect then to be lower I'm just wondering if running them at 85% all the time is too much for them. I guess that's the way to find out though. And yes that's idling in traffic with the ac on and a big old tranny cooler in front of the radiator. lol. When I'm moving it stays around 205*. Also I'm just wondering if 212* is acceptable for burning off contaminates in the oil?

They're only going to run when your not cruising down the hwy. Wouldn't worry. Oil temp is also typically hotter than coolant as well....not a issue

[morepowerjoe]

Yeah my oil temp is right on with my coolant temps at 210* or so.

[gtstorey]

Oil temp is calculated anyway and probably isn't right after you start changing things.

[morepowerjoe]

Found this in all data.

The auxiliary gauge module displays the engine oil temperature based on the information from the ECM. The ECM converts the data from the engine oil temperature sensor to a engine oil temperature signal. The ECM sends the engine oil temperature signal via a High Speed CAN-Bus signal to the BCM. The BCM then sends the information via a Low Speed CAN-Bus signal to the auxiliary gauge module to display the engine oil temperature.

So does this mean it's a calculated value?

[acutron42]

I would have to say yes it is absolutely calculated. Temperature is simply being converted into an electrical signal. If you hooked up a mechanical gauge where the fluid actually flows through it that does the same thing, just less complicated. I bet they would both be very close. Think of the old Honeywell home thermostats with the mercury years ago. When the heat went up the coil expanded & moved the needle. Both principals had to be calculated. One is mechanical & one is electrical. Just converting one form of energy to another.

[gtstorey]

Actually what I have read on here is that the 2010-2012 uses a mathematical model to calculate the the oil temp for the auxiliary gauges. I just checked the 2010 service manual and it shows the an oil level/temp sensor but it labels the temp circuit for the MYC which is the automatic transmission code and I can’t locate the wiring diagram that actually shows the sensor, only the connector end view and ecu pin. So I really don’t know exactly how it comes up with the gauge reading. There have been reports on here of people putting very large oil coolers on for road racing and not seeing any difference in oil temp readings.

[morepowerjoe]

I don't know if this really helps but here it is.

I'm not actually sure what I'm looking at. It looks like a sensor connected to the ecm?

[gtstorey]

Yes that shows a connector for oil level and temp to the ECM but the MYC indicated that it is for the auto RPO code, as does the L99 label on the ecm. But the ground side of the sensor shows both L99 & LS3. My 2010 manual didn't have the temp sensor shown, but I do have the oil level.

It could have a temp sensor and also mathematical model for displayed temp. GM may have been concerned with the oil temps in the top of the motor for the L99 for the VVT & DOD and the oil temp in the pan may not have been telling a complete story. They may use the oil temp in the pan along with other data like RPM and engine load to calculate a different temperature. Pure speculation on my part, though based upon some of the post on here from people that usually know what they are talking about. Justice Pete was told by GM engineers that it used a mathematical model.

I've never looked to see if I even have an oil level sensor and if it's got three wires. I'll try and check this weekend.

[acammer]

Originally Posted by gtstorey

Are you think the fans are like injectors and should be ran less than a certain percentage or you will cause them to fail? I don't think the fans work like that, and in fact I don't think our fans are PWM but are instead "discreet" which mean the percent fan speed doesn't mean much that the fans are off at 0%, both fans on a low at 50%, one fan on low & one on high at 75% and both on high at 100% or something similar. I don't know the actual percentages that relates to the various fan speeds, but I think this is the control scheme.
I'm also not sure how it interpolates between these percentages. It may just go up to the next fan setting as soon as it goes above 50% or 50% may be a range that extends to 62%. But at some point your 85% is either running 1 fan on high and 1 on low or both fans are on high. Neither is running at 85%.

At some point the fans only have so many rotations in there, but I wouldn't worry about some percent of running being to much and then a little less meaning a lot longer life.

Your understanding of the fans and how those tables work in the ECM is more or less correct. GM has PWM (pulse width modulated - variable speed) and discrete (on/off via relay) fan configurations for different vehicle types. For example, a C6 Corvette has a PWM fan, while a 5th gen Camaro has a pair of discrete fans with a low and high speed circuit.

There are essentially three tables in HPTuners that govern fan control, State vs. Desired %, Output Control vs. State, and Desired % vs. ECT (engine coolant temp).

Desired % vs. ECT is what you've been modifying, and basically saying at x coolant temp I want x% fan output. However, with discrete relay control the percentage is then interpreted by the State vs. Desired % table. This looks at the Desired % and produces a state - 0, 1, or 2. These "states" are then read by the Output Control vs. State table to modulate the relays that run the series/parallel low/high fan circuits.

In stock configuration, moving from state 0 to 1 occurs when the desired % reaches 50%, which occurs at 221*F ECT - the fans come on at low speed.

If the coolant reaches 228*F, then desired reaches 90%, and state 2 is set - the fans run at high speed.

If state 2 is set, and then the ECT drops to 217*F, then desired drops to 40%, and state 1 is set - fans go back to low speed.

If state 1 is set, and then the ECT drops to 210*F, then desired drops to 24%, and state zero is set - the fans turn off.

Basically - when you hit 221*F the fans will run on low. They'll kick back off at 210*F, unless they cannot cool the car and temps rise to 228*F, in which case they will run at high until they cool the car to 217*F, and then they'll go back to low, and kick off at 210*F.

You can run them as aggressively as you like, but in general you want to make sure they aren't just constantly on (unless you have a setup which is otherwise unable to maintain temperature - probably not this crowd). I try to figure out what the car will do for cruising temps on the highway on a hot day, and then set my low speed cut-off a few degrees above that, so that I'm not going to run the fans at highway speeds, but on a hot day I keep it close to that point when idling. I turn the low speed fans on at 199*F, high speed at 203*F, and then cut them all off at 196*F - I have a 160*F T-state which runs at about 180-185*F on the highway depending on ambient temps.

Running the fans aggressively all the time, especially on high, will shorten their life, and potentially bake/melt components of the wiring - they were never desired for a constant duty cycle.

This is a screenshot of how the tables look in factory configuration.

[morepowerjoe]

Well thanks again Andrew for the information I really appreciate your input as always.

[gtstorey]

Thanks for the input. The only tables that I have actually looked at are for the Turbo Cobalts and they only have the Desired % vs. ECT available in HP Tuners but still use the discreet fan setup. This causes problems for some that have used these in kit cars where one of the fans get deleted. They try to get the fans to cut on in percentage steps and it doesn't work right.