I have a 2007 C6 LS2. With all the heat recently I was wondering is there a way to run a by-pass switch that will turn the fans on earlier? For example like at 150 degrees?

Thanks

I have a 2007 C6 LS2. With all the heat recently I was wondering is there a way to run a by-pass switch that will turn the fans on earlier? For example like at 150 degrees?

Thanks

take it to the local chevy dealer and I'm sure they can reprogram them

The coldest the fan settings can be set is 192 F on all LS2 & later engines. A product like HPTuners (http://www.hptuners.com) would help you though.

Pull the water temp connector off the block/head (wherever it is?).

This may(?) over-ride what the ECM will do automatically if the water temp sensor failed.

You now are in the 1Atmo backup code set. It's complicated and easy at the same time EFI/ECMing the tech, but say you unplug the connector--turn the key on--listen for the electric fan to come on--turn off key--reconnect the water temp sensor harness connector--turn key on = Did the fan come on or did the ECM revert back to analog for that water temp sensor is working proper?

Once your engine is up to a running temp, the fan will go off as if it is normal function. But for the initial cool off the engine loophole on hot days? Try that and see if it works as well on my basic computer type engine backup the hack into the ECM is that loophole.

If you have HP Tuners you can set the % in the 192* block anything above about 30% and the fan will run continuously even with a cold engine.

But if you do this or any tuning and have an engine, transmission or drive train failure your 5 year/100K mile warranty is voided.

I have a 2007 C6 LS2. With all the heat recently I was wondering is there a way to run a by-pass switch that will turn the fans on earlier? For example like at 150 degrees?

Thanks

The fans are controlled quite differently then with the C5 where via tuning you could command the fans to come on at any temp and at what temp fan 1 and fan 2 are running.

C6's fan tuning table starts at 187 deg which is at the point the Tstat begins to open so the fan cannot be commanded to come on sooner then that.
From 187 deg you can command not only if fan is on or off but at what percent of rotation fan is spinning.

A dealer cannot program fans nor would they be allowed to as the car when fed tested was certified and in part GM runs higher temps solely for smog purposes thus a dealer commanding fans to cool the powertrain would mean GM would have to do the federal testing again.

Being the fans are being commanded as a rotation percent there is a controller for that and makes it harder to override that as it would set error codes.

You would not want to disconnect like the water temp sensor as this would cause PCM to think the water temp was -40 C which would cause PCM never to go into closed loop and cause engine to run poorly and trip multi error codes

Best path is to put a lower Tstat in and then tune the fan's PCM table for more rotation.
It that still is not cool enough then go with a better flowing radiator and/or vent the hood to reduce engine bay temps.

Fans are turned off above speeds of 35 MPH unless the A/C is turned on.

Since 192 is the coldest you can command the fan controller to turn on, the only benefit to a colder thermostat is at highway speeds.

Basically, around town you will have a choice of fans on all the time (0-100% fan speed at 192F+) or no fans at or below 192F and a progressive fan rate above that point.

The guys at HPTuners (http://www.hptuners.com) are working on a solution to cooler fan temps like they have on the 05 Vettes.

Basically, around town you will have a choice of fans on all the time (100% fan speed at 192F) or no fans at or below 192F and a progressive fan rate above that point.
The guys at HPTuners (http://www.hptuners.com) are working on a solution to cooler fan temps like they have on the 05 Vettes.You can program in what ever percent you want at 192F. It doesn't run at 100% fan speed. I had mine programmed in around 35% at one time and it ran slow but all the time.

It would not be just at highway speeds but any speeds over 35 MPH when fans are commanded off.

LSx engines tend to cause oil temps to be hotter then water temps.
This then causes that oil heat into the water temp so any time water temps can be lowered helps pull that oil heat down

Cooler Tstat allows radiator then to handle heat spikes better then stock is over 200 degrees and any spikes ramp the water temp higher. Add stock fan settings and engine temps can be in the 220s and any heat spikes only makes it worse
This heat also then also inflicts higher air temps so now you have a stock PCM calibration that monitors water and air temps and yanks the **** out of timing so anytime a stocker can run cooler reduces how much timing is pulled and uses less fuel as leaner/hotter causes hotter exhaust and O2s responding as feedback to PCM to dump more fuel in.

Lastly hotter engine oil is and using 5W30 is not what I'd want for high RPM engine loads. Using a thicker weight only slows the oil flow and retains more heat and hotter lighter oil is more prone to become blowby.

Since 192 is the coldest you can command the fan controller to turn on, the only benefit to a colder thermostat is at highway speeds.

Basically, around town you will have a choice of fans on all the time (100% fan speed at 192F) or no fans at or below 192F and a progressive fan rate above that point.

The guys at HPTuners (http://www.hptuners.com) are working on a solution to cooler fan temps like they have on the 05 Vettes.

It would not be just at highway speeds but any speeds over 35 MPH when fans are commanded off.

That's not always true, if coolant temps get higher than the enable temp the fans will come on (progressively) as they are supposed to. That's the advantage of the PWM fan setup on the C6. It's not simply an on/off design like the C5 and earlier.

And along the same note: If you put in a value above zero% in the 192F column of the fan settings that will be the minimum fan speed all the time as any temperature below 192F will use the value at 192. So your fans will run all the time if you have a colder thermostat. And when you first fire up a cold motor - fans will be on. Not good for longevity of the fans/fan controller.

I see what you tuners are saying here, but what is the benefit of getting a 160 or even 170 degree thermostat if the thing won't kick on till 192 degrees?

If the car is overheating the owner has much more problems then if what temp the fan is coming on but that is something very rare and nothing to do with choosing what temp opening Tstat is used.

As it is the fan are even controlled to run after the engine is turned off and what the engine temp is and also how long the fan will run when engine is turned off.

Being the C6 only has 1 fan as the C5 has 2 and that the radiator of C6 is slightly smaller then the C5 it is even more important to use a colder Tstat and proper tuning of fan table in PCM.

Fan control is not the same in a 2005 V a 2008 Z06.
To me having 2 fans in the C5 does a better job then the 1 fan in C6 because since the one fan is being controlled as to rotation percent and tuning it to run higher rotation can also leave to a lower life of th fan and a better chance that fan controller failing.

That's not always true, if coolant temps get higher than the enable temp the fans will come on (progressively) as they are supposed to. That's the advantage of the PWM fan setup on the C6. It's not simply an on/off design like the C5 and earlier.

And along the same note: If you put in a value above zero% in the 192F column of the fan settings that will be the minimum fan speed all the time as any temperature below 192F will use the value at 192. So your fans will run all the time if you have a colder thermostat. And when you first fire up a cold motor - fans will be on. Not good for longevity of the fans/fan controller.

I see what you tuners are saying here, but what is the benefit of getting a 160 or even 170 degree thermostat if the thing won't kick on till 192 degrees?

I'd would not suggest just changing the Tstat without also adjusting the fan rotation via a tune.
If reason to change to a lower Tstat and performance is in mind then having a decent tune down not only gets colder water and oil temps but anywhere from 20-30 HP gains and even more for torque.

Keep in mind the hotter engine bay is over long term also effects everything from seals, O-rings, wiring insulation and even current draw as to the coils and injectors are much hotter.

I think you are missing the point: You can not control the fan speed (other than having it run all the time at some preset value) below 192F.

I think you are missing the point: You can not control the fan speed (other than having it run all the time at some preset value) below 192F.

It is not ALL the time, below 35 MPH controller controls the AMOUNT of fan rotation and yes it can be controlled as the PWM is the whole reason it can be and why the fan has its own controller now mounted on fan shroud.
Clearly if the value is 20 at one of the temp cells in the fan table then the speed of rotation is not the same as a 90 value.

The engine cooling fan is a variable speed fan.
The engine control module (ECM) controls the fan speed by sending a pulse width modulated (PWM) signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the cooling fan motor in relation to the pulse width modulated signal.

Cooling fan speed is effected by many different conditions and can be adjusted from 10-90 percent duty cycle , 90 percent is considered high speed fan.
When multiple cooling fan speed requests are received, the ECM uses the highest cooling fan speed of all the requests. The ECM commands the fans ON under the following conditions:

• The engine coolant temperature goes above a calibrated amount.

• The engine oil temperature goes above a calibrated amount.

• The A/C pressure reaches a calibrated temperature.

• After the engine is shut OFF, if the engine coolant temperature at key-off is greater than a calibrated amount, or the A/C pressure is greater than a calibrated amount, the cooling fan is set to low speed. The fan will shut OFF if the temperature or pressure drops below a calibrated amount. The fans will shut OFF after 2 minutes, regardless of coolant temperature.

• The engine coolant temperature goes above a calibrated amount.

That calibrated amount can not be set below 192 F as 192 is hardcoded. So below that you HAVE NO CONTROL other than the fan% at 192 which will continue *below* the 192F setting.

Been there tried that on a LOT of LS2/LS3/LS7 engines. If you want the fans on all the time - by all means put in a cold thermostat and set the 192F value to anything above 0%.

You can quote GM documents all day long but we have looked over the GM binary code and know exactly how it works.

And if you want to be a tuner on this forum pony up and become a sponsor.

I have to laugh when people say don't quote GM as to be saying GM is wrong and the hacker knows better, sounds like a statement Paul of efilive would say as many times it has been found their tuning tool to be flawed.
What your saying is what your tuning tool can or cannot do and not what other tools can do.
It is not 192 deg, it's starting fan point is 187 deg.

You like to tell me what nameplate would want any fan on above around 35 MPH when natural airflow above that speed does just fine ?

Sounds like the norm of a vendor wanting to shut people up by the claim of we have to PAY to have the freedom of speech but you need to go back and find out why PWM is used and why there is a fan rotation table in the PCM.

That calibrated amount can not be set below 192 F as 192 is hardcoded. So below that you HAVE NO CONTROL other than the fan% at 192 which will continue *below* the 192F setting.

Been there tried that on a LOT of LS2/LS3/LS7 engines. If you want the fans on all the time - by all means put in a cold thermostat and set the 192F value to anything above 0%.

You can quote GM documents all day long but we have looked over the GM binary code and know exactly how it works.

And if you want to be a tuner on this forum pony up and become a sponsor.

Maybe you have a communication problem here, VPW to KW2000 or something of that sort.

The lowest breakpoint for the fan table is 192 F. That was my original point and still the point. Yes you can command anywhere from 0-100% fan speed at that breakpoint. That happens to be the normal open temp for a stock 192 T-stat right? I can dig the GM source code up for you if you need to see it for yourself but I think we will bore the hell out of the SV members though. Probably have already.

35 MPH *should* be enough airflow going through the radiator. But what if it isn't (big cam high compression or blower application with I/C in the way) and temps creep up but not to 192F assuming you have a zero value at 192 to keep the fans off below that point? And that doesn't address the idle temperature issues that most are concerned with after putting in a 160 T-stat and not being able to have the fans come on *properly* below 35 MPH. It takes an O/S mod to make that happen. Guess you are the O/S mod god then?

Sorry, I don't and won't use EFILive. But yeah they have been wrong.

[sarcasm alert] You're apparently not a tuner since your website promotes tuning so I guess you don't need to financially assist the forum you are trolling for business on and guess it's needless to say your signature says: Custom E/PCM tuning

Most freedoms are paid for in some way or another. They aren't free and must be defended when challenged. [/sarcasm alert]

Being I custom tune (http://www.smokinvette.com/corvetteforum/showpost.php?p=35071&postcount=3)
Yes I do custom tuning (http://www.smokinvette.com/corvetteforum/showpost.php?p=35393&postcount=4)of most GM cars/trucks from 1984 to present and also test many different mods to see if they help or hurt performance as to are they worth buying or waste of money.
I have tuned well over 1,000 C5s (http://www.smokinvette.com/corvetteforum/showpost.php?p=27519&postcount=9)and those that were almost stock still gain about 30 HP and even better overall torque.

Since your not just a member but a VENDOR/TUNER why not pony up and help Alex and Greg out a bit? That's all...:bs:

I see what you tuners are saying here, but what is the benefit of getting a 160 or even 170 degree thermostat if the thing won't kick on till 192 degrees?

:iagree: This is what I was thinking. What sense is there to have anything less than 192 thermostat then?

The lowest roation point is 87 C that is not 192, it is 188 F deg
and your logic is still off.
The whole point of this thread is does the engine have to run as hot as GM has it and if not then performance is lost ?

2nd was your stating the fans are on all the time.
3rd just because the first config cell in fan table is 192 degrees does not mean the water temps cannot run cooler then that
Unless hot weather using a lower tstat the water temp can stay lower then 187 deg once car is in motion but below 35 MPH,
My 1999 LS1 stroker even at high 11.3:1 compression, at 500 HP and using a 3.73 transaxle gear rarely reaches over 183 degrees at idle and and above 35 MPH lives around 175 degrees even at 6900 shift points.

So not matter that the fan config table is using a lower tstat can in fact in most cases live below that 187 trip point.

PWM was used on purpose with the C6 as GM saw it was better to control rotation then the effects of 2 fans being on most of the time.
If a fan at high speed maximun rotation is 1200 RPMs then clearly if setting rotation to 30% of that yes the fan can be on but it is barely moving any air volume.
If you do not understand PWM let's build the circuit

http://teamzr1.com/temp/pwm.gif

That is the point, fan is not on all the time and that is good but if replacing the zero value GM set at 87C to 70% rotation then right off the bat the temps will go lower then 87 C due to the volume flow thus with a colder tstat the engine stays most cases below 190 degrees.

Rotation percent was not used for no reason and people claiming fan is on all the time or cannot run below 87C is not correct as I have C6 Z06s that are maintaining low 180 deg water temps even in this hotter weather

http://teamzr1.com/temp/fan.jpg

As to your personal attacks/remarks, common when someone cannot handle anyone elses experience is shade the whole subject but I have been at this many decades and know the game and since you did not answer all my WHYs in above post you also might ask why

1. the 1990-95 ZR-1 used double amount of oil in the LT5 the base engines did to reduce oil heat
2. the new ZR1 and Z06 also use 10 plus quarts of oil
3. boosted mods like supercharger use innercoolers to reduce air temp
5. ZR1 goes so far as cooling air by water and air, and even oil is sprayed to underside of pistons to lower their temps

So lowering heat overall is good, myths about best performance when runiing stock temps does not pass the smell test.

As to freedoms, don't tell me about it I was fighting for it in V.N back in late 1960s and I intend to use those rights.

Maybe you have a communication problem here, VPW to KW2000 or something of that sort.

The lowest breakpoint for the fan table is 192 F. That was my original point and still the point. Yes you can command anywhere from 0-100% fan speed at that breakpoint. That happens to be the normal open temp for a stock 192 T-stat right? I can dig the GM source code up for you if you need to see it for yourself but I think we will bore the hell out of the SV members though. Probably have already.

35 MPH *should* be enough airflow going through the radiator. But what if it isn't (big cam high compression or blower application with I/C in the way) and temps creep up but not to 192F assuming you have a zero value at 192 to keep the fans off below that point? And that doesn't address the idle temperature issues that most are concerned with after putting in a 160 T-stat and not being able to have the fans come on *properly* below 35 MPH. It takes an O/S mod to make that happen. Guess you are the O/S mod god then?

Sorry, I don't and won't use EFILive. But yeah they have been wrong.

[sarcasm alert] You're apparently not a tuner since your website promotes tuning so I guess you don't need to financially assist the forum you are trolling for business on and guess it's needless to say your signature says: Custom E/PCM tuning

Most freedoms are paid for in some way or another. They aren't free and must be defended when challenged. [/sarcasm alert]





Since your not just a member but a VENDOR/TUNER why not pony up and help Alex and Greg out a bit? That's all...:bs:

You make me :rofl: As to being in this for decades. Well, heheh, me too, but what's your point? I'm not exactly a noob to tuning as you suggest. I've been through more code in my lifetime than I care to discuss.

I completely understand PWM ridiculously well as it's used on many things other than mundane fan controllers and it bores me when those implying they are intellectually superior blather on. It's old tech used way back in the electronic carb days (well much further back than that but you get the point).

Regardless, if you set any value above 0% in the *192 F slot* (LS2-Edit has been wrong on many occasions - but we're hair splitting here). The fan will come on at that fan speed% any time the engine is running and idling, or as *you* say, below 35 MPH. Not exactly a good idea for fan longevity even if it's only 10% - Right?

We're talking about LS2/LS7 engines here anyway not the LT5's which is your specialty according to your website. Is running an engine a bit cooler good? If it did everything GM wanted they be doing it too. Cold engines impact emissions and fuel economy negatively. I ran a CARB approved 3 bag test lab for years. Just because you can pass the 15/25 MPH smog check doesn't mean it's a good combination or calibration. :lol:

Do cooler engines make more HP? Emphatically yes! Any engine dyno will tell you that.

BTW: HPTuners has an update in the works that will allow fan control down to 163 F. Good news for all!

Enjoy your day. :D I think we've beat this dead horse long enough.

We see it all the time as the Gods of "hot engines are fine" mindset where they believe because GM has to do things a certain way for smog and to maintain high CAT temps that by magic heat does not kill or reduce performance.

Those who drive a Corvette for what it was designed for know when racing what heat does and it is just not added friction.

As you reduce heat simply with using a bit colder Tstat and proper tuning when fan(s) are on has all the positives of reducing not just the water temps but also the oil and intake air.

As a small example taking a 2007 Z06 and simply replacing stock Tstat with a 180 degree and correct tuning of fan control we see in the OBD data compare

Fuel trims are not as lean, whuch reduces engine knock,
water temp at idle staying at 180 deg which shows those claiming C6s cannot run cooler then 192 degrees do not have the hands on experience and as you see the intake air temp is lower.

There is many reasons to not want long term the engine and everything in engine bay to live in 220-240 plus degrees but as the facts show using the PCMs own OBD data that C6s can operate lower then 192 degrees as in this C6 Z06 at 180 degrees at idle in 90 degree southern Ca day and because of that then the air temp in airbridge is cooler which we know colder air is a better aircharge in cylinders.

The problem happens because there is no high profits in selling a Tstat and the myth that somehow having any engine run at high temps makes better HP then using COOLER air/fuel

I suggest using both hands and grabbing into and holding the fuel rails for even 20 seconds with a stock setup and then wonder what that does to the cylinder charge using hot air and fuel along with the knock and lower timing is for overall best performance

http://teamzr1.com/temp/cmp.jpg

The whole point of a forum and this discussion is to bled the myth that colder is bad and C6s cannot maintain lower then 192 degee water temps and todays LSx engines do not transmit heat out as well as the older steel blocks and also transmit more noise then steel does which effects engine knock so cooler is better and for the cost of a $40 Tstat can be far better in gains then a $500 aircleaner

By all means continue beating this dead horse... :rofl: :rofl: :rofl:

I don't think I said anywhere that a 180 Tstat was bad... You kill me! :rofl: