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2001 VDC/SC One of a Kind
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Here's my take.

Fan operation is dependent on factors associated with engine temp, engine load, rpm, gear selected, gear running, vehicle speed, ATF temp, AC operation, electrical load. All these incorporate the overall needs of the engine to operate efficiently. Fan operation is dependent on available electricity also.

The temperature value is actually a moot point. The ECM doesn't know temp, it only knows voltage feedback from the several sensors and does the math according to a math table programmed in the module's software based on engineering tests performed during manufacture and coupling of various drive set ups. Engine size, transmission, gear ratio, volumetric efficiency, boosted or N/A, etc.

My thoughts on the different maps is it is part of the ECM's learning curve. The tables are guides for the ECM to learn from and it builds on the tables based on need in the same way it learns fueling, shifting, ignition timing, knock correction and recognition of input from the driver's foot. To determine whether the ECM is using only one table, you would have to log hours of driving in various situations, then determine which table it is using based on the recorded data. You would have to log a lot of different PIDs simultaneously.

You won't get anything from a Subaru engineer. I've tried. They won't talk.
 

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2006 OutBean, 2005 LGTW
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@plain OM, hello!

I apologize in advance for my English...
You could understand in what case the ECU uses table A or B (C)?

In my car Outback 2.5CVT (2012 MY, for Europe), two tables are used - A and B. Moreover, the values in table A are different from yours, and table B is the same as yours.
In order to slightly lower the temperature of the engine, I replaced the standard AA200 thermostat with AA230, which has a full opening temperature of 91C (196F) instead of 95C (203F).
In the ECU Subaru firmware for the thermostat AA230, the temperatures in table A are 3-5C lower than for AA200, but the values in table B are almost the same (only two parameters are lower by 1C).
I have been traveling by this my car for 3 months and during this time I noticed that table B is used to turn on the fans.
Trying to figure out how best to change the temperatures in the Radiator Fan Modes A / B (ECT) tables.
I'm curious... what made you go with a lower temp thermostat?
 

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'10 3.6R Outback Limited, 2zr swapped Toyota Yaris track toy, '12 Mazda3 skyactive
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438 Posts
Here's my take.

Fan operation is dependent on factors associated with engine temp, engine load, rpm, gear selected, gear running, vehicle speed, ATF temp, AC operation, electrical load. All these incorporate the overall needs of the engine to operate efficiently. Fan operation is dependent on available electricity also.

The temperature value is actually a moot point. The ECM doesn't know temp, it only knows voltage feedback from the several sensors and does the math according to a math table programmed in the module's software based on engineering tests performed during manufacture and coupling of various drive set ups. Engine size, transmission, gear ratio, volumetric efficiency, boosted or N/A, etc.

My thoughts on the different maps is it is part of the ECM's learning curve. The tables are guides for the ECM to learn from and it builds on the tables based on need in the same way it learns fueling, shifting, ignition timing, knock correction and recognition of input from the driver's foot. To determine whether the ECM is using only one table, you would have to log hours of driving in various situations, then determine which table it is using based on the recorded data. You would have to log a lot of different PIDs simultaneously.

You won't get anything from a Subaru engineer. I've tried. They won't talk.
Hmm that is interesting, didn't realize it was based on so many factors. I'm pretty sure my Yaris is a simple on/off (around 210*F) based on coolant temp alone so this is new to me.

I have noticed that my fan in my 3.6R typically doesn't run at all until the temp hits 213*F. The highest I have seen the temps was around 221*F right after going up a hill at a slow speed in the summer heat. I was stopped at a stop lift when I noticed those temps.

Seems high but all within coolant ranges I suppose. I do plan on replacing the rad,thermostat and hoses as preventative maintenance before next summer to avoid the notorious hose blow off that people seem to be stranded from.
 

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Subaru Outback 2.5 CVT (2012MY, for Europe)
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I'm curious... what made you go with a lower temp thermostat?
Hello!
I'm not sure I can convey my thoughts as a result of “Lost in Translation” ...
Now I already think that I went in vain along this path (I mean replacing the thermostat). Perhaps this is a mistake. But I want to try to understand this issue, although there are practically no chances. Especially after @cardoc's answer.
At that moment in time (replacing the thermostat), I did not go into the study of the issue. I thought everything was much simpler - about the same as on Yaris @Tmontague and it would be enough to lower the temperature on / off of the radiator fans by 4C - in accordance with the value by which the new thermostat opens earlier.
How I came to this situation. Bought a car 06/30/2019. The results of monitoring the coolant temperature and oil temperature (ActiveOBD) upset me a little. In the summer, every time I drove from home to work and from work to home (about 8 km and 20-25 minutes), the temperature of the coolant and the temperature of the engine oil were heated to 99-100 C (210-212F). This is due to the fact that I do not turn on the air conditioner if the street is not very hot and there is no sun - due to certain health problems. If the air conditioner is on, the temperature was 94-96C (201-205F). When driving along the highway, everything was fine too - at a speed of up to 130 km / h (80 mph), the temperature of the coolant and the temperature of the engine oil were in the range of 91-93С (196-199F). That is, I was worried about the temperature only when traveling around the city with the air conditioners turned off - these are my main movements by car.
But at the same time, I compared the temperature regime with my previous cars, in which the temperature of the coolant and the temperature of the engine oil in this mode of movement indicated problems with the engine cooling system. Probably, for Outback, this is the normal operating temperature range, despite the fact that the service manual described a slightly different logic for turning on the fans (table A), and the fans on my machine always turned on in accordance with table B and allowed the coolant and engine oil to warm up up to 100С (212F). At the same time, I thought that stopping the engine at such temperatures (212F) probably led to subsequent local heating of the engine oil by several degrees C. I do not know the dependence of the degree of degradation of engine oil at this temperature range, but it seems to me that heating the oil is above 100C (212F) - this is not very good for him.
Since I did not know how the machine was operated before me by the previous owner, I took certain steps: removed and washed the radiators, replaced the coolant, replaced the thermostat with a standard AA200, replaced the radiator cap and the water pump. After that, the operation of the cooling system has not changed. Therefore, I replaced the thermostat with AA230, whose full opening temperature is 4C lower than that of AA200 in the hope that thus (after changing the temperature of the fans) the temperature of the coolant and engine oil will not be 100C, but 96-97C. But with lower fan temperatures, the situation was more complicated than I thought.
So I found myself in this incomprehensible situation.
Thank you for reading and responding)
 

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Subaru Outback 2.5 CVT (2012MY, for Europe)
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Here's my take.

Fan operation is dependent on factors associated with engine temp, engine load, rpm, gear selected, gear running, vehicle speed, ATF temp, AC operation, electrical load. All these incorporate the overall needs of the engine to operate efficiently. Fan operation is dependent on available electricity also.

The temperature value is actually a moot point. The ECM doesn't know temp, it only knows voltage feedback from the several sensors and does the math according to a math table programmed in the module's software based on engineering tests performed during manufacture and coupling of various drive set ups. Engine size, transmission, gear ratio, volumetric efficiency, boosted or N/A, etc.

My thoughts on the different maps is it is part of the ECM's learning curve. The tables are guides for the ECM to learn from and it builds on the tables based on need in the same way it learns fueling, shifting, ignition timing, knock correction and recognition of input from the driver's foot. To determine whether the ECM is using only one table, you would have to log hours of driving in various situations, then determine which table it is using based on the recorded data. You would have to log a lot of different PIDs simultaneously.

You won't get anything from a Subaru engineer. I've tried. They won't talk.
Thanks for your reply!
 

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Subaru Outback 2.5 CVT (2012MY, for Europe)
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Here's my take.

Fan operation is dependent on factors associated with engine temp, engine load, rpm, gear selected, gear running, vehicle speed, ATF temp, AC operation, electrical load. All these incorporate the overall needs of the engine to operate efficiently. Fan operation is dependent on available electricity also.

The temperature value is actually a moot point. The ECM doesn't know temp, it only knows voltage feedback from the several sensors and does the math according to a math table programmed in the module's software based on engineering tests performed during manufacture and coupling of various drive set ups. Engine size, transmission, gear ratio, volumetric efficiency, boosted or N/A, etc.

My thoughts on the different maps is it is part of the ECM's learning curve. The tables are guides for the ECM to learn from and it builds on the tables based on need in the same way it learns fueling, shifting, ignition timing, knock correction and recognition of input from the driver's foot. To determine whether the ECM is using only one table, you would have to log hours of driving in various situations, then determine which table it is using based on the recorded data. You would have to log a lot of different PIDs simultaneously.

You won't get anything from a Subaru engineer. I've tried. They won't talk.
And yet, it seems to me that the decision to use a particular fan operation table by the ECM is made on the basis of simpler logic.
Firstly, there are only two temperature tables in the ECM for a large number of different combinations of the factors you listed (engine temp, engine load, rpm, gear selected, gear running, vehicle speed, ATF temp, A/C operation, electrical load). Engine temp (coolant temp), vehicle speed, A/C operation - everything is clear here, the logic is written in the service manual (in addition to using more than one table). ATF temp also affects inclusion - this has been found empirically.
Secondly, when using an air conditioner or the presence of oncoming air flow (as opposed to traffic in a traffic jam), one or another table does not have any effect on engine cooling if the fans do not turn on when the temperature reaches the value in the table in combination with the vehicle speed and load on the air conditioning compressor - usually it doesn’t come to this - I have never seen.
It is very likely that I am wrong, I want to hear different points of view.
P.S. Sorry for my English...
 

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2001 VDC/SC One of a Kind
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There are multiple fuel tables in the ROM and fueling is dependent on a lot of factors, not just your foot and a couple sensors. There are things within the RAM and ROM on these cars that takes a lot of reverse engineering to see because the information is not published, so nothing is on a basis of "simpler logic". Keeping things simple is the easiest, so if you are having a coolant issue, or believe you do, then it would benefit you and the rest of the readers if you could post a rundown of what has transpired and where it all started. You may be chasing a squirrel around a tree.
 

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Subaru Outback 2.5 CVT (2012MY, for Europe)
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There are multiple fuel tables in the ROM and fueling is dependent on a lot of factors, not just your foot and a couple sensors. There are things within the RAM and ROM on these cars that takes a lot of reverse engineering to see because the information is not published, so nothing is on a basis of "simpler logic". Keeping things simple is the easiest, so if you are having a coolant issue, or believe you do, then it would benefit you and the rest of the readers if you could post a rundown of what has transpired and where it all started. You may be chasing a squirrel around a tree.
@cardoc, thanks for your reply.

I meant it is not based on simple logic, but the logic of deciding on the use of a particular table is slightly simpler than the analysis of all the factors you listed. But its only my guess.

I agree with you that it is very difficult to figure this out in the absence of information and answers from Subaru engineers.
And I am not inclined to simplify complex things, but I also know that some people, fearing something unfamiliar, complicate everything in advance and this makes it difficult to get to the bottom of the truth. This I do not mean you, it's just an observation.

"if you are having a coolant issue, or believe you do, then it would benefit you and the rest of the readers if you could post a rundown of what has transpired and where it all started" - I previously tried to explain this. Probably not clear. I have my own statistics on coolant and engine temperatures under various operating conditions, but I am sure it coincides with the experience of others. And it's hard for me to give explanations in English. Unfortunately.

The initial goal of my participation in this forum was to find out if someone has information on the principles of choosing an ECM temperature map. I understand that reasoning in the absence of the necessary knowledge will not lead to finding the right solution.

"You may be chasing a squirrel around a tree" - interesting proverb)))

I understand the essence of your answers. But I'm not sure that I am expressing my thoughts correctly.
Thanks again for participating.
 

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2008 JDM Outback 3.0R, 5EAT
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371 Posts
Good thread it's same for my '07 H6. Occasionally the fans do not run whilst driving in slow moving traffic based on the radiator fan mode selection described here. I'm fairly sure the sensors, electrical and coolant are OK and have plenty of log file data that shows sometimes ECU just didn't want to run the fans. This vehicle doesn't have DTC P0483 available.

This 12 minute drive chart shows ECT gets up to 100C in the final third whilst in slow moving traffic in drive and A/C off. The idle switch is set quite a lot (yellow line, RHS axis) but the radiator fans are not activated allowing coolant temperature to rise. This doesn't happen every drive and I appreciate the ROM's are complex but curious to know what the radiator fan mode selection logic is, perhaps we'll never know!

487080
 

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Discussion Starter #31
. . . curious to know what the radiator fan mode selection logic is, perhaps we'll never know!
Thanks for adding this.

We probably will not know all of the logic, but some observations could still be made from logs.

In the earlier part of the graph, there seems to be more periods of the car moving. The fan control is using the lower temperature mode, turning the fans on at around 95 C when the idle switch is on.
In the latter part of the graph, the stopped times appear to be longer, and the idle switch is on more. Under these conditions, the fan control is in mode B, turning them on initially at or above 100 C. (I mentioned seeing this exact same pattern in the Edit paragraph of post #8 above.)

I've never logged the idle switch. Do you have a complete log with it? I'd like to see when it comes on and goes off relative to other parameters.

The idle switch might be part of the injectors management when the car is coasting. When the accelerator is released, there's a fuel cut, i.e., injectors are not providing adequate fuel to keep the engine running. But the engine still turns because the torque converter is initially locked, and will transfer the car's momentum to the engine. As the car slows, at a combination of speed and rpm the torque converter lock-up clutch is released, and the injectors are brought back on-line in order to prevent the engine from stalling and maintain AT pump operation. I presume that the idle switch changes from 0 to 1 are related to the injectors being turned back on, i.e., to ensure the engine will maintain idle as the car slows to a stop. (At other times the switch is off because the accelerator and throttle are advanced and perhaps the torque converter is locked, so there's no need to invoke idle control.) The ECM might monitor the time the idle switch is on, along with other parameters, and determine from that which mode map to use.

I'll add the switch to available log parameters, but with the restrictions here, even though it's summer, we don't get out a lot, and when we do, there's few if any traffic delays. I'd have to simulate a long start-stop situation to get the engine temperature up for a similar log!
 
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