Hello,

I hope i'm right here with this topic, since the theme has only indirect relation with tuning.

The last days were really hot here, about 40°C peak outside temperature. I burned my fingers when i pulled the oil dipstick, and this finally made me wondering, if the temperature inside the engine compartment might be to high. There are also known cases of molten valve covers for my model, so i think, i'm not to wrong with that.

The Engine Coolant Temperature is controlled by a map-thermostat. The Coolant is kept straight at 106°C on low load, the engine oil temp is about 110°C. Last value is calculated by a model applied in the ECU, there is no real sensor. Some people measured the oil temp and some say, the calculated value fits the real value, some people say it doesn't.

I was wondering if i can reduce the coolant temp or change the front fan control to make life easier for the engine. Some Questions about this:

1. Can somebody name me some related maps and their functions? I did some research on several forums, but it seems, that this topic is barely to zero discussed. I know where i can find some related map areas, but i don't have any description/map names for that areas.

2. I'm wondering how the Coolant and Oil Temperature regulation cohere. The Oil and Coolant are connected 'mechanically' via a heat exchanger, so possible regulation concepts could be:
 - Coolant temperature is regulated(in fact it is) and oil temperature is only monitored to prevent overheating
 - Coolant temperature is regulated and oil temperature targets affect the coolant control loop
 - Oil Temperature is regulated by functions that finally control the map-thermostat. The final coolant temp would be a kind of "side effect" in this case.

Im asking this, because applying new values to the maps could have strange effects if there are unknown dependencies.

3) Can the Temperature-Targets/Fan-Control be changed dependent from the measured outside temperature?

Some hints for maps would help me to do try&error, but if you guys have some deeper knowledge, i would be happy if you can share it. Thanks in Advance!

No doubt, you're absolutely right. Maybe i didn't point out my goal properly: With cooling down coolant and as a consequence of this probably also oil temperature, i try to reduce waste heat into the engine compartment to reduce the overall temperature. The Problem is on low load and speed only. On High Load, the additional fan is activated and coolant temp is regulated to 80-90°C anyway.

If i succeed, i can still change oil to another viscosity. In fact, i'm driving oil thicker than factory recommended anyway. This is common on these engines due to oil consumption and works fine. I can still change back to specification. Or do i still have a mistake in my idea?

Someone skipped their physics class. The engine produces the waste heat regardless of temperature.
In fact it is most likely going to produce MORE heat if you force it to run at lower temperatures than it was designed to and reduce fuel efficiency as well as increase wear on engine components.