Hey there,

I'm getting ready to start tracking the car and wanted to add a few features to the car. After installing the modifry ect, I noticed a few things and wanted to make sure it was ok.

Using modifry stock settings, when I was bleeding out the air in the rad, I noticed I would hit 4 bars and the rad will not come on. After about 3 minutes at 4 bars, (205-219)both fans will come on, run for about 20-30 seconds and then turn off. The car still showed 4 bars. Eventually after a couple of minutes, both fans would turn on for another 20-30 seconds and shut off.

Shouldnt the fans continue to run until the car/temp reaches 190 in the radiator? I just installed a new fan switch as well so don't think that is the issue.

I know The stock honda temp range (160-235) for 3 bars will fall in line with what I'm seeing but after doing a few searches, it seems most cars run around 190-205. Temp in my area ranges from 70-90 degrees.

Thanks in advance.

 

The stock fan switch is supposed to close at 199°F according to what I've read in the manuals, but that doesn't tell us how much hysteresis the mechanical switch has (how much lower the temperature must drop before the switch opens again). My guess is that it would be 10-20°, which would cause the fans to turn off somewhere between 189 and 179. However, the radiator fans can be activated independent of the switch by the ECM. Obviously the air conditioner status can trigger the fans to run, but I think it's possible the ECM could turn them on based on other factors such as the ECT sensor readings, however I have no idea how that internal logic works if it exists at all.

That said, even if you assume the fans turn off when the radiator temperature reaches 190° that does not mean the temperature of the coolant in the back of the intake manifold (where the ECT sensor is located) is the same temperature. Some heat will be lost as the water flows towards the radiator so I think the manifold water will always be a little hotter.

Another thing you should know is that there is some variability in the accuracy of all temperature sensors and the OEM ECT sensor is no exception. I would expect to see up to a 5% variation in sensor accuracy, and on top of that the reading can be affected by how close the ECM maintains the designed 5.000 volts sensor power. And of course the ECT module is not 100% accurate, though it's much better than the 5% I mentioned.

If you want the temperature gauge read a little differently you may want to think about changing the ECT module set points, which can be done with a PC that has a serial port or by using an inexpensive USB to Serial adapter ($10?). All it takes is editing a text file and then "printing" it to a generic text printer that you configured to use the serial port.

 

Thanks modifry for the quick response. I don't mind the stock settings the device comes with but just wanted to make sure I didn't have another issue. Many seem to run at 180-190 running an aem ems but not sure if they have the fans running earlier or installed a fan switch.

I can always run a lower temp fan switch or hot wire the rad fan but if running at 205-215 is normal, I'll keep it the way it is.

Product works great by the way. Also have your original shift beeper working like a charm after about 10 years with your glove box organizer.

 

From what I was told by a "Honda guy" years ago the engine was designed to run in the 200-215 temperature range but you may want to do some research on your own.

It seems many people try to make the engine run cooler but I'm not sure why. Maybe it's a carry-over from 30 or 40 years ago when many cars had marginal cooling systems and as soon as you drove it hard or did anything to increase power they overheated so you were forced to make cooling system improvements. If AEM users are running temps below the stock thermostat setting (190°) I assume they changed the thermostat, either that or they are not accurately reading the temperature. "Back in the day" that was not uncommon as the early EMS boxes that were put on S2000s had inaccurate temperature curves but I thought that was fixed years ago.

If you're developing so much power you need additional cooling then you need a bigger radiator or higher-flow water pump. Changing the minimum operating temperature with a different thermostat or fan switch doesn't improve cooling capacity, it just forces the engine to run in a lower temperature range under low-speed or low-power conditions. Seems to me if lower temps were better then Honda would have done it. Actually I think they already did, as I believe the S2000 runs cooler than other Hondas of the same vintage.

I ran a Comptech SC (6psi) on my first S and did several track days a year in Southern summers and never had a cooling problem with the stock radiator, thermostat and temp switch. Sure, it would hit 4 bars on my ECT module on the track but never more than that because there was enough air flow to keep the radiator cool. The only time I saw 5 bars was when I'd come off the highway for gas and parked for a 5 or 10-minute fuel stop (due to heat soak while the engine's off).

 

Yea haven't seen the 5 bars but do noticed it goes from 3-4 bars while driving. The airflow driving seems to make a big difference. Also forgot to mention I have a mishimoto radiator so I would imagine what should help lower temps a bit but I'll keep an eye on it and make sure I never see 5 bars unless I'm in a situation similar to yours with heat soak or turning off/on the car after 10-15 minutes.

 

Not just Hondas but all gasoline engines run most efficiently in this temperature range although the range may be a bit wider such as 195°F to 220°F. Engine oil viscosity is measured at 100°C or 212°F which is right about when the engine coolant stabilizes in that range. Oil temperatures inside the engine are typically 20°F higher than the coolant.

Car cooling systems all do a pretty good job of maintaining coolant temperatures. Even towing my travel trailer across the Pennsylvania mountains my Expedition engine coolant stays in the 190° to 200°F range and never exceeds 200°F. Cylinder head temperatures spike occasionally over 210°F but rarely.

The OEM Honda temperature gauge is more like an idiot light with some bars illuminating in a very wide temperature band but for most of us that's all the information we need. Race cars may need/want more details to monitor trends but I'll bet few of us look at the gauges other than the speedo and fuel too often.

Knowing how we all like trivia: Marine engines are typically raw water cooled. Engine coolant is pumped directly from whatever water the boat is running in and keeps the engine at the right temperature. They use a thermostat just like cars. Running in fresh water these engines typically use a 180°F thermostat. If this same thermostat us used in salt water the salt will precipitate out of the solution as temperatures next to the block are higher and eventually fill the engine up with salt. This is why outboards are (or should be) flushed after running in salt water. Inboard engines will often use a colder thermostat in the 140° to 150°F range to keep the salt in solution but the don't run as well. Coolant-Raw water "intercoolers" are also used for a closed cooling system to protect the engines. Expensive. Thus endeth the trivia (for now).

-- Chuck