I have recently discovered that my S is overheating while idle (waiting for the light to change ect.) but temps are perfect when in motion. My self and three Honda trained mechanics looked over the car and have yet to figure out why this is happening. (Temp gage hits 4 bars when idle, normally 3 while driving)

So far the following has been tried without luck.
-Fan temp switch replaced. (currently using aftermarket low temp switch)
-Engine thermostat replaced (Stock OEM)
-Radiator hoses all replaced.
-Car flushed and bled. (by Honda once and twice myself)
-Engine compression checked (all psi's were between 216 to 220)
-Oil / Coolant remain clean.

Note: We've done just about everything but park the S on an incline to assist with bleeding.

Mods of note on the car.
-2.5L inline Pro motor
-AEM EMS (Tuned at Stage Six in Jacksonville, car was tuned slightly rich to be on the safe side)
-Low Temp fan switch. (Aftermarket J's Racing, kicks on at 176F instead of 194C)
-Stock Thermostat.
-Modifry's Engine Coolant Temperature Driver (Modifry Stock settings used)

Stock Modifry settings are as follows:
One other thing of note... Seams that with the radiator cap off i can see the coolant lowering when the cooling fans cycle on. I am wondering if the thermistat is opening and closing after cooler water reaches it thus creating a feedback loop?

Anyone seen this situation before or have an idea what could be at fault here?

 

this is an odd situation. with all that youve tried. i would look at the water pump next

 

I wouldn't say that a 4th bar being lit with the Modifry ECT driver is overheating at all.

Given your ECT driver settings it's not overheating until the 6th bar is lit.

 

I'd think air in the system. Do you have underdrive pulley on? They will spin the pump slower at idle and I've seen track cars overheat at idle because of it.

 

I'm still using the stock pullies with my motor and I also forgot to post in my mod's list that i have the Hondata intake-header heat shield. (had it installed now for about a year now without any problems)

Side note: I didn't notice any overheating issues until after i had the car tuned... Not really sure how tunning the S could lead to an overheat situation if the car was tunned slightly rich? Car ran great during the 1000 mile break in prior to the tuning. (All non-VTECH driving under 5k rpms)

As for the car being 4 bars... It just seams very unnatural for the car to go past 3 bars if it is idling on a cool day. (60-70F with 70% humidity, mild day for Jacksonville Florida) I am thinking if it's like this now it will be undrivable during the summer when it's 100F +.

 

I plan on replacing the waterpump and upgrading the stock Thermostat to a lower temp aftermarket one. (J's racing)

Beyond that I cant think of anything else that would really make a differance.

Question: Are the low Temp fans switches and thermstats made to be used as a set? I had read somewhere a long time ago that they were and that signifigant problems could rise if they were used seperatly.

 

You can't compare your temp gauge reading of 4 bars with a stock car.

Modifry's ECT driver allows more resolution than stock. The 4th bar on a stock AP1 doesn't light untill 220+. It's documented on Modifry's website.

I think you're trying to fix something that isn't broken

 

4 bars, as you noted, is 190-205 degrees with the ECT fix. Thats perfectly normal, I don't know what you are concerned about???

 

Indeed, I've done a dyno day with an OBDII scanner connected to the cars, watching coolant temp, and 190 to 205 is 100% normal. My bike doesn't even turn on the fan until it hits 220.