I spent 8 hours on Saturday changing plugs, fuel filter, serpentine belt along with a coolant flush/180 stat and installed my PCMforless chip.

93 LT1 A4

I drained/cleaned the radiator, overflow tank and the fill tank. The coolant came out like brown, chunky diarrea!! Screw the PO!

I installed the 180 stat, refilled the coolant and even used the GM required sealant tabs due to the aluminum heads. Kind of like a stop leak they used.

I installed the chip and everything runs great and the car definetly runs smoother and quicker.

Last night I drove the vette 60 miles round trip to my parents house and the car sat at 194 degrees with the electric fan running the whole time. I believe the fans now come on at 192-194 instead of 225-230.

Last night was 50 degrees and the fans were running the whole time while driving on the highway at 70.

Is this bad that the fan is going to run constantly with the PCM for less chip lowering the fan temps???

What temps do the guys with the 180 stats and lowered fan temps normally run?

 

Obviously, you'll want to hear from your LTx cohorts, but....

My L98 does the same thing with the same programming and a 180-stat. My problem is that L98's have two temp stats and the one for the display can be 10-15 degrees different than the one for the display/stat. So, even if you're stat is pushing 180-degrees (give or take -- depending on it's accuracy), the ECM might be seeing something different.

If it's like mine, the ECM rarely sees temps lower than 188 (mine is set to 193/on and 188/off) to shut off the fans. OTOH, it does usually shut off on the hwy. (Since I unplugged my aux fan that is....)

I think the biggest issues are the accuracy of your stat and what the ECM is actually seeing. Who knows...maybe PCM4Less even mistyped the value for the fan-shut off????

I'm also curious if your LT1 has a primary/aux fan combo...and how that's setup. In my case, I'd need a different fan setting for my aux fan to plug it back in. I picked a temp range that's too cool (195/on 180/off)

 

Are the fans on when you first turn the key to run after the car has sat and the engine is cool?

 

@thearborbarber

I dont know if the fans come on after the car has sat.

After I flushed and cleaned the system I let the car run for 10 mins and come up to temp to make sure the thermostat opened, bleed the system and check for leaks.

When the car hit 192-194 the fan kicked on.

Then that night I drove 30 miles to my parents and the temps did not break 194-196, but they also did not go lower than 192 even while driving on the highway. Which means that the fan is continuously blowing and never shuts off!

I came home last night and parked the car.

I will drive it this week and then park it for 20 mins and then when I run it again see what the is and if the fan comes on...

Dont get me wrong I am happy the temps stay below 200...before the flush, stat and chip the temps were around 200 and would spike to 220 just sitting at a light for 1 minute or stuck in traffic.

Just wanna make sure this isnt an issue with the fan constantly running if the fan on temp is 194 and its still 50 degrees out.

I hope in the summer when it is 80 degrees out the coolant temps are stuck at 200 and the fan is just blowing away all day long while driving

 

In those temps, the fan shouldn't run all the time.

 

190's sounds like perfect temps to run at possibly you got a little greedy with the settings. I would unplug the fans and go for a ride on the interstate at 60 to 70 mph if it runs hot doing that I would get a better radiator. If it runs at about 195 set fan on for 210 and off at 205 it is just not as hot as you imagine it to be. The actual boiling point of antifreeze / water mix and a 16 lb cap is in the 260 to 270F range.

 

Remember coolant temperature is NOT the only input to the fan control.
Others, namely the AC Compressor, also will turn the fans on.

Also the AC compressor runs in other climate control positions beside the AC ON setting.

Actually it sounds to me like his cooling system is now working properly, probably as a result of his cleaning up the cooling system.



BTW if you want to experiment with what coolant temperature causes the fans to run, be sure you have the climate controls in the OFF position.

Also the 192-193 is the "indicated" digital temperature when a 180 stat fully opens...may not mean that the fans have come on or off

 

It has been a long time since I've looked at the programming but the fans generally turn off after you hit a certain road speed. The A/C will kick the fans on but my car is so loud I honestly couldn't tell you if they still run at speed with the A/C on.

 

Can't remember the last time I had to run the A/C when it was 50 outside. But, I'm sure it happens.

My assumption is the A/C would be off at those speeds and the only thing keeping the fans running was overly aggressive fan controls and/or a stat that was not working properly.

In a thread during the past year, I proposed that 180-stats don't really maintain exactly a 180 temp. That's when I was reminded that dash temps aren't what's going on elsewhere in the motor. But I have an L98 where water heats up after it leaves the stat housing and makes it's way around the circulation path. When I monitored the ECM's perception of temps, I saw they were about 10-deg higher after warm-up.

On LTx cars, they have reverse cooling, so I'd GUESS that stat temps are the lowest water temp in the motor. As such, with the fan settings provided, I didn't see any reason the fan shouldn't be shutting off on the hwy (at 50-deg). And, from that other thread, it seems reasonable to conclude 180-stats really should maintain 180-deg at the housing when fully opened.

Basically, you want air flow across the radiator to provide enough cooling for the engine. Fans are typically used to supplement air flow when the vehicle comes to a rest. With proper settings, you shouldn't need them running when the vehicle is sufficiently moving.

It really can't hurt anything though....At the most you'll burn out the fan motor(s) faster.

 

It increases the load on the alternator, which actually costs some fuel and a small amount of HP. In a perfect world therefore, you would want them to not run if the road speed is sufficient.

Like I said I don't know if mine run at highway speed or not but I really feel like they don't. Anybody wanna crawl under the hood and take a look while I'm doing 60?

FWIW in relatively cool weather cruising my LT1 sits at 190 degrees, it does go up when I come to a stop until the fans kick on.

 

So, do LT's have two sensors like L98's?

Now that my brain is more awake, I remembered my dash (thermostat) temps are higher than the ECM-monitored temps. So, while the thermostat is keeping the coolant at/near 180 (where the ECM is looking), the dash display is seeing the block temps (outside the cylinder walls) in the mid-190 range.

To me, this means a 160-stat might keep block temps in the mid-170 range (for a gen1 engine). On an LT engine, I wonder if the result would be about same with a 180-stat? (I don't recall if anyone has ever covered this???)

Reverse cooling would be the unknown for me. Since LT's have reverse cooling, I'd assume stat temps would be highest at the thermostat -- not in the block. I also don't know where temps are measured for LT stats and for the ECM.

 

Yes the LT1 has 2 sensors. One is on the water pump housing and the other is one of the cylinder heads (which head depends on if it's a F-body or a Y-body). The one on the water pump housing feeds the ECM and the digital gauge. The one in the cylinder head does nothing but drive the analog gauge.

I know that if your water pump ever quits completely (IE faulty connection to your electric pump) the temp at the water pump housing will stay steady or drop slightly and the temp at the cylinder head will rise. This leads me to believe that the digital gauge is therefore reading the temp on the output side of the radiator rather than the input side.

This also tells me that the actual cylinder head temperature will probably be slightly higher than the indicated digital readout.

 

The LTx's do have two sensors. One in the water pump and one in the passenger head. One is for the gauge and one is for the fans to read.
The fans generally shut off at 45 mph, or depending on where the programmer changed it to.
If AC is on, then the AC controls it. If you have a 180 stat, pcmforless would probably put the fans on around 200 and off at 190. But the best way to find out is get a-hold of pcmforless and see what they did.

 

The AC compressor runs, for example, anytime you are calling for DEFROST....to reduce the humidity in the air. The AC compressor on my 96 runs in all positions except "feet only".

The AC compressor is now running at temperatures below 50 calling for the cooling fans to run! Nothing to do with keeping the passenger cool.

On my LT4 with a 160 stat you can see the thermostat crack open at an digitally indicated 169 and the temperature usually stabilizes at about 173 in cool ambient temperatures. My fans are programmed to come on low speed at 180 and high speed at 190.....never been above about 195 with this setup (PCMforLess programming). With the old Hypertech Programming the car NEVER went above about 176 and usually ran at 173.

Not 100% sure, but on the LT4 the fans run regardless of highway speed.....I understand on some years the fans were programmed to turn off at highway speeds, at least that is what has been posted on the forum many times.

 

The issue is the thermostat. LT1/4 180* thermostats *start* to open at 180*. They are fully open around 192* (put an LT1/4 180* stat in a pan of water with a thermostat and you can verify this yourself). Basically the thermostat is just getting to "open"...then the fans cool the coolant fast enough that the thermostat closes and the cycle repeats.

If you want to stop the fans from running all the time, replace the 180* stat with a 160* stat or have PCM4Less burn you a new chip with a different fans "on" temp.

Will it hurt anything if you leave it? No, other than a little more load on the alternator and wear on the fan motors.

 

great feedback and discussion guys....

One night this week I am going to let the car idle until the fans kick on to see what temp they come on at with the digital reading on the dash.

I believe its 192-194. I will also try to email or call Alvin @ PCMforless to see what fan settings he gave me.

It's always something with a Corvette!!

 

Just to follow up on my thread since most people ask a question and never report back to the forum...

Took the vette out for a quick spin tonight as it was a cool 55 degrees.

I cleaned out a some leaves in the air dam between the radiator and let the car idle and warm up to 192 degrees and the fans kicked on.

Drove the car around on a 4 lane road with stop lights every 2-3 miles.

The car pretty much sat between 192-196 cruising, stop and go. The car never went above 198 degrees stopped at a light for 1-2 mins.

So my problem is still that the car doesnt drop below 190-192 so I dont think the fans are shutting off.

Anyone else out there with a PCM for less chip and have a 180 stat with lowered fan temps??

What are your fan temps set at? Is the fan running constantly?

 

Until you get data from your chip showing where the fans are being asked to shut via speed and temp, i recommend you take your car to a long road, pull over. Turn of engine, then disconnect both fan relays on left side of fan shroud. Restart engine, and drive down highway to see what temps it gets to. Monitor your temps closely, but at highway speeds it will have sufficeint ariflow to cool the Vette.,

 

So on what setting did you have your heater/defrost/AC ?

Did you get an answer from PCMfor LESS???

They programmed my fans to come on at 180 with a 160 stat......

...and on cool/warm days my car will usually run around 173 partly because the fans are being called to operate from the AC compressor, not from coolant temperature....and BTW I can see my 160 stat cracking open at an indicated 169..

 

I had my fans programmed to come on at 205 instead of 230 on my 94.
Alli did was send them an email and asked that they make that modification for me on the tune i am using. Works like a charm.