1.4T E78 - Desired ECT not following the table

Hi everyone,

I noticed a strange behaviour about the desired coolant temperature setting on my car, 1.4T LUJ engine with E78 ECM (OS 12669508).
Here's the 18170 - Desired ECT table from my stock file:
Attachment 126460

With the table set like this, the desired coolant temperature I see in my logs is following nicely, oscillating between 105?C and 90?C.

I wanted to lower the temps in this table but for some reson the ECM doesn't care. I'm seeing random desired ECT in my logs, sometimes 100?C, sometimes 98?C...
I even tried re-flashing the stock file and only playing with this table but I can't get around it.

Attachment 126461

I don't know what could be the cause of this, any ideas?

First what I found out is, that the coolant temp depends on the enviroment temp. My settings are 94?C and 90?C. When it is cold outside and I mean "damn" cold, then the ECU doesn?t "care" too much about it.
In my case in numbers, I have around 94?C to 102?C. Most of the time around 100?C, because the thermostat opens just a very little or in no way. The radiator stays cold.
That makes sense too, because lets say, you have an enviroment temp of around -2?C. And if the thermostat would open, then a huge load of damn cold water would run through the engine and it would run too cold.
Therefore it stays closed, but the fan turns on. With warmer environment temps, it works great. I mean..we are talking about a 1.4L engine ;)

Further what I found out, that the regulation is always +/- 2-3?C as the desired value. In my case: 90?C = down to 86?C in summer and 94?C = 96-97?C before the thermostat opens.

Therefore in your case, everything should be fine.

I'm relieved, thanks for sharing your experience! I thought there was something wrong with my tune :p

I did further searches and there is indeed a limitation to the desired ECT based on ambient temp on these ECM, just as you said.
Not sure if it's the the same strategy for all 1.4T but in my case it looks like it's using the mesured ECT at startup to set this limitation.

If the mesured ECT is between 10C and 5C, desired ECT minimum is set to 97,5C.
Between 0C and -5C, minimum is set to 100C and below -10C the limit is set to 105C.

I am glad, that I could help you :)
I didn?t find any possibility in HP TUners to change that. Did you?

The data is there in the ECM but unfortunately, it isn't mapped by HP Tuners so you can't edit it.
However, if you have the user defined parameters feature you could add the parameters yourself and do the modifications.

You'll need to find the address of two 7x1 tables in your tune. I added the addresses of where the data is in my tune but it's likely yours are gonna be different.
- one table defines the maximum allowed desired ECT in relation to the ambient air temp (address 0x078164)
- one table defines the minimum allowed desired ECT in relation to the ambient air temp (address 0x078180)
Both tables shares the same column axis (address 0x07819C).

And for reference, here's the data I found in my tune:

	1	2	3	4	5	6	7
Ambient Air Temp	10	5	0	-5	-10	-20	-40
Max. Desired ECT	105	105	105	105	105	105	105
Min. Desired ECT	97,5	97,5	100	100	105	105	105

Hope it helps!

A quick update about this, took some time to map the relevant parameters and it worked fine.
Didn't noticed any problem keeping the ECT stable with -1C outside, I will keep an eye on this with lower temps but it sounds all good!

Attachment 126867

Thanks for your feedback. Based on your ECU, my car is from the same brand - just the "smaller" brother ;)
Would you share your *.xdf table?

I have been in Contact with the support team. They added your tables in the latest beta. In the fan Section you can find those settings :cool:

I have installed the latest beta but I can not see these tables in the fan section. What do I miss?

I knew about the other ect tables but I never bothered to try and find them.

I believe, your car is different, even they share the same platform/parts. Since I am from Germany, there are some differences.

I have a 2012 Cruze / Astra-J with the E78 and 1,4t engine.. no start stop system. The user defined parameters do not work on my car, tabels show 0

Does anyone have the correct parameters ? They must be somewhere because the ECU does ignore desired ECT during cold weater

Quote:

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Originally Posted by bobl66

I have a 2012 Cruze / Astra-J with the E78 and 1,4t engine.. no start stop system. The user defined parameters do not work on my car, tabels show 0

Does anyone have the correct parameters ? They must be somewhere because the ECU does ignore desired ECT during cold weater

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Different E78 ECU operating system number, that's why. Memory layout changes sometimes. Can you link the .hpt file here? I could try some offsets.

Here is the file, thanks for checking

Quote:

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Originally Posted by bobl66

Here is the file, thanks for checking

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Here is the XDF

Attachment 141814

Attachment 141813