FALSE! FALSE! FALSE! We don't all know such nonsense. This would be a good time to study your FSM and any other EFI reading materials, you can get your hands on.

Once the engine is warm enough to go into closed loop, somewhere around 140° - 150°, the ECM only uses temperature to control the fan(s) in cars that have ECM controlled fan(s). As far as changing the engine running characteristics, the ECM only controls the fuel mixture and idle speed when cold, taking place of the choke. The ECM does NOT lean the mixture beyond stoichiometric, nor does it retard the timing in an effort to keep the engine hot.



WRONG! WRONG! WRONG! As explained above, the ECM is incapable of controlling the engine to make it maintain a given temp.

Think about what a thermostat does and how it works. Once the coolant gets hot enough to open the stat, the thermostat has done all it can do. Once the thermostat is open, it is open. If your engine runs at 200°, it will run at 200° whether the thermostat was opened at 195° or at 160°. Adjusting the computer to prevent it from heating up the engine, isn't an issue because the ECM doesn't TRY to heat up the engine.

RACE ON!!!

PS. I DO believe that some computers WILL raise the idle speed when the engine gets too hot, in order to increase the coolant flow through the engine in an effort to lower the temp. But no way does the compute have a mission to maintain a min. temp.

 

Thanks, you may be the first person I have actually read that said that specifically, I even had a guy who still races corvettes tell me the computer tries to get the motor hot because GM wanted the temp up there.

Thanks

cal

 

That sums it up as short as anybody is ever going to say it.

 

I run a 160 or 170 thermostat - i don't think it substantially affects power - it may allow for more wear on the engine - I doubt if it is measurable or quantifiable.

I do it for 1 reason - same as what SJW talked about. It gives me time to figure out if i am heading for a cooling meltdown. If I am running at 195 or 200 - boilover and failure will happen right now!

If I am running a 170 thermo - and I see my car creaping into the 180s - i can short shift - lower rpm - get open air, check the radiator for obstruction - find a place to safely stop - with water - think about whats causing the problem. i can figure it out before I get into the danger zone.

without that cushion of time - when it goes bad, it goes bad in a hurry - and your options are very limited!

My setup is a little different in that is is a track car - so I have no AC condensor on it - and I deal with big heat - but i can tell you that having a 170 degree thermo saved me from a likely engine rebuild this week. (ask me how I know about engine rebuilds an stuck themostats! )

carl Johansson

 

except that my car runs at whatever thermostat I put in - a 170 thermo - I will run between 168 and 175. Right now I have a 180 thermostat - it runs between 177 and 182.

If the system starts to fail - i see the heat creaping up and can deal with it.

If I ran a 195 - with a fan turning on at 220- i would be very limitted in time and options if it went bad!

Carl Joahnsson

 

I don't think you have a stock cooling system though, right? Since you track your car, what other mods have you made to the cooling system?

Just changing to a 170 degree stat by itself will not keep your car running at 168 - 175.

It's your cooling system capacity, and how it transfers heat that will determine what the max. temperature levels off too.

I still stand by what CFI-EFI said. A 160 stat is just as wide open as a 190 stat is, when the water temperature reaches 220.

If your car normally runs in the 200 - 220 range with the 195 stat, a change to a 160 stat will not make it magically run at 160 - 170.

 

Your situation is a little different than most on here with DDs or even fair weather cruisers. It is a little difficult to pull over on the shoulder, to cool when you are 3/4 the way through the 5 mile course on the salt. I speak for the prevailing conditions for MOST of the useage by MOST of the forum members.

A page or so back I even explained the reasons one can deviate for drag racing, and why it works only for the short term.



Mine will usually run just above stat temp, at highway speeds, too. What temp does yours run, at an idle for 15 minutes, or 20 miles of stop and go, 15 mph max, bumper to bumper, traffic?

RACE ON!!!

 

Me too. I have never seen what I wrote written before, because I have never seen your statement made before. We get a lot of old wives tales, folk lore, rumors, and W.A.G.s on here from time to time, but that one was a first for me.

You might take the time to "logic out" and try to understand how and/or why, next time someone tries to sell you a story like that. Good luck, and...

RACE ON!!!

 

Good Post!
Bernie

 

It is a stock radiator that was recored last year. A stock water pump, and the stock fan - but the fan runs continuously! but i also removed the AC condensor - so I have a straight shot of clean air flowing through the radiator. With this setup I haven't had any cooling issues - unless part of the system failed. I caught a heating problem when a fan quit running, and this week was able to catch an intermittantly sticking thermosta by paying close attention to my heat gauge.

I'm running in the central valley of california - and often track the car in the mojave - and have not had any cooling issues with this setup! Even with temps often exceeding 100 degrees.

As i previously posted here - I ran 1.5 hours to an autoX - ran the auto X and ran home in 95 degree heat from sea level to 2500 feet to my house and the car opperated at 182 the whole way - with a 180 theromstat.

Carl Johansson

The car runs at whatever thermostat temp I put into the car

 

Cooling has never been an issue for Bonneville runs - but I also drive the car on road tracks - like Reno Fernley or Willow springs or Spring mountain - so the car is getting worked out really hard for 20 minutes at a time 4 or 5 times a day- and I do drive it around the mountain roads for an hour or 2 at a time - and also drive it to work - 45 miles and back regularly - in the central valley heat (100 degrees is the normal summer temp here).

You are right that my situation is different - I just wanted to point out that it is not difficult to make a corvette run at whatever temp the thermostat is.

traffic - stop and go etc - I may heat up to 10 degrees over thermostat - if i'm in LA traffic for an hour or so - but It never gets to 190 - unless I have a problem in the cooling system!
Carl

 

I changed my radiator to a Dewitt's. Installed a 160 thermostat and chipped it so the fan comes on at 175 F. One day it hit 107 F. There was an accident on the freeway. I was at a dead stop with the AC on for 1/2 hr. The temp hit 227F. That's not bad. A few days ago I removed my pre cats. I replaced my 2 1/4" Y pipe with 2 1/2" I notice an improvement in acceleration. I also noticed the temps ran about 10 degrees cooler. I just came back from a trip. I took a 5 hr trip in summer heat of about 100 F. I ran the AC all the way. It never got above 195F. That was in traffic.

 

You would have had the same coolant temps with the factory thermostat. In your case, both thermostats would have been wide open and the coolant temp would settle where the radiator gets rid of heat as fast as the engine makes it. Wide open thermostats have the same flow rate!!!!!!!!!!!!!!!

 

Sorry, I never read thermostat threads, they all go the same direction and the same people say the same things.

To answer your question, no you dont have to put in a chip. The generic chips are worthless. Generally they only reset the fan temps, which combined with a lower-than-stock stat, help keep the engine running cooler. Some bump timing, but I would just bump the base timing to 8* and let it be.....independent of the stat you run.

Assuming there are no cooling issues (see the overheating link on my page), I would just install a fan switch.

 

You are right. That is not bad... It is horrible performance for that combination of components. A week or so ago, we had similar conditions. My coolant temp didn't hit 214° F. I have the 24 year old factory radiator, a stock water pump, a fan on switch temp of 206° F and off, 196° F, (no aux fan) and a 180° thermostat. You must have yours screwed together poorly. You should be spitting ice cubes out your tail pipes with that combo.



And he wouldn't have been wasting gasoline, and fan motor life (yeah, I know, you say they are cheap) in the process.

RACE ON!!!