2017 Hyundai Elantra 2.0L - ECT operational theory

[CB900F2]

Hi All...

I own now a 2017 Elantra with their new 2.0L engine(I still own my 08 Yaris, just gave it to my son) and wanted to throw this question at your guys since I have found a lot of members on this forum are pretty knowledgeable.

My Elantra uses a ECT(Electronic Control Thermostat) which is basically a normal thermostat with a heater element integrated into the expansion wax assembly of ECT to which will allow premature opening of the thermostat by the heater heating up the expansion wax to open the thermostat.

I have been pulling live data off the PCM with my Bluedriver OBDII and I have found what I think to be very very odd coolant temperature readings..

I have posted three data readings. The one data reading that is showing the very linear rise in coolant temp and then in steady state its also linear, this is my 2006 Honda Odyssey and it has a non ECT thermostat.

The other two that you see are of the Elantra, and for the life of me, I do not see the logic in both the non linear rise in temperature to normal operating temp. The normal operating temp for the Elantra is 100DegC. and then once it finally hits approx 100DegC, the constant up and down swings in temp +- 10Deg C..

I know very little on the concept of the ECT and its part of the engine design in trying to maximize efficiency based on engine load and cooling the engine down during heavy loads and increasing the temp under normal loads but this constant swing makes no sense to me.

The graphs only show the cars speed, but I am also capturing the following data and I can post a link to a Onedrive folder if you wanna see the full data.

- Engine Load %
- Throttle Position
- Engine RPM
- Incoming air temp (throttle body)

One key data point I am not capturing is the "ECT Heater voltage the PCM is sending to the ECT" I spoke with Bluedriver and they are not able to grab this info as Hyundai uses some special codes that they can not read for this data point.

Again.. the algorithm the PCM is using to me makes no sense, and the live data readings are all from when I drive home>>work, and then back from work>>home. I take the same route every day, and drive conditions are pretty much the same except for the daily temperature outside. Even with the other data I am capturing, my laymen understanding, I do not see from the other data point why the need for this constant swing..

If anyone can make some sense of this temperature swing, please let me know.. My only concern is longevity of my car and engine...

I have asked on other Hyundai/Elantra forums if anyone who has a obdii reader that can capture live data on a 2017+ (2.0L) and post it, but no luck so far to compare.

Thanks all!!