A Slightly Geekish Look At FSI Coolant Warm-up

Good Evening,

Going back to the log file I realised I had not included a graph.

The hole in the middle is when the engine was off while I did my shopping. I did make an effort the give the accelerator some welly on the way back and it shows.

1677786730725.png


The climate was off in the above graph in contrast to the graph I posted recently when the climate was on, this one

index.php


No noticeable bend in the first graph at about 50℃ with climate off compared with the second graph with climate on. Enough evidence for me that when the climate is on it does not make serious use of the coolant heat for 5 minutes until the coolant has warmed up a little - the engine matters more than the freezing occupants.

Andy
 
Andrew said:
Good Evening,

Going back to the log file I realised I had not included a graph.

The hole in the middle is when the engine was off while I did my shopping. I did make an effort the give the accelerator some welly on the way back and it shows.

View attachment 105183

The climate was off in the above graph in contrast to the graph I posted recently when the climate was on, this one

index.php


No noticeable bend in the first graph at about 50℃ with climate off compared with the second graph with climate on. Enough evidence for me that when the climate is on it does not make serious use of the coolant heat for 5 minutes until the coolant has warmed up a little - the engine matters more than the freezing occupants.

Andy
Click to expand...
How do you think this engine bias, (rather than cabin), heating is controlled?
Mac
 
Catnip64 said:
@Andrew needs to prove the existence of this elusive N279 valve!
Click to expand...
I'm convinced it exists, and the difference in warm up with climate off, (and how cold it is in the cabin), compared to when climate is on can only be down to a change in the coolant circulation path. It's also explained in the mapped cooling system SSP, (SSP222),
If @Andrew is correct, then that valve is also closed during the first few minutes of engine running, to ensure the engine warms up as soon as possible. It's just this bit that I'm not convinced of. If we could find it, we could, (hopefully), monitor the supply to it.
Mac.
 
It was only a throw away line at the end.

PlasticMac said:
How do you think this engine bias, (rather than cabin), heating is controlled?
Mac
Click to expand...
I do stress the statement was in context of climate ON and thinking about I should have added working in AUTO. In such a case the answer to your question would be the climate with software so designed, it simply has not to open flaps to let heat out of the heater matrix. There does seem to be an observed point when the climate opens up. May be I am wrong.

Under manual control of cabin heating I agree with @Catnip64 the N297 would have to exist.

Personally I think the N279 is highly unlikely to exist. Google searches yield nothing but the odd reference to some later Audi models, nothing on the German club either and most significantly no posts about it failing which surely would have happened by now after 20 years. What was the picture of Evros you posted?

Here's an idea, monitor and log the coolant hose that is the return from the heater matrix at the bulkhead with a contact or infrared thermometer and at the same time log the G62 engine outlet temperature. Draw a graph.

Andy
 
Well, I will be replacing the evaporator, hopefully before the summer really sets in, so we will know!

@Andrew Thanks for reminding me that I have an IR thermometer!
 
Andrew said:
It was only a throw away line at the end.


I do stress the statement was in context of climate ON and thinking about I should have added working in AUTO. In such a case the answer to your question would be the climate with software so designed, it simply has not to open flaps to let heat out of the heater matrix. There does seem to be an observed point when the climate opens up. May be I am wrong.

Under manual control of cabin heating I agree with @Catnip64 the N297 would have to exist.

Personally I think the N279 is highly unlikely to exist. Google searches yield nothing but the odd reference to some later Audi models, nothing on the German club either and most significantly no posts about it failing which surely would have happened by now after 20 years. What was the picture of Evros you posted?

Here's an idea, monitor and log the coolant hose that is the return from the heater matrix at the bulkhead with a contact or infrared thermometer and at the same time log the G62 engine outlet temperature. Draw a graph.

Andy
Click to expand...
If the Motronic ECU can control the HVAC ECU so that the flaps were held closed until engine outlet sensor hits a setpoint, then that would work, as @Andrew says. With no flow through the matrix, heat loss would be much reduced.
Mac.
 
PlasticMac said:
If the Motronic ECU can control the HVAC ECU so that the flaps were held closed until engine outlet sensor hits a setpoint, then that would work, as @Andrew says. With no flow through the matrix, heat loss would be much reduced.
Mac.
Click to expand...
I think it it is quite possible the engine ECU can signal the climate via the canbus communication, 'okay Mr. Climate the coolant is hot enough to open your flaps and do your thing' or put the coolant temperature on canbus for the climate to pick up which will be programmed with some trigger value.

If or how it it would work with manual heater controls I have no idea.

Andy
 
Andrew said:
I think it it is quite possible the engine ECU can signal the climate via the canbus communication, 'okay Mr. Climate the coolant is hot enough to open your flaps and do your thing' or put the coolant temperature on canbus for the climate to pick up which will be programmed with some trigger value.

If or how it it would work with manual heater controls I have no idea.

Andy
Click to expand...
Well, I may be looking at recanting, (surely not?).
Looking very closely at the switch I thought operated the mythical valve, it has a symbol alongside what looks like a potentiometer. Anyone recognise the symbol?
I tried a Google search for the tadpole like image, but no luck. Just hope it doesn't spawn.

Mac.
Screenshot 2023-03-03 20.25.32.png
 
Also, just realised that the system described in "SSP 222 Mapped Cooling" is based on the Siemens Simos ECU, not the Bosch Motronic ECU, which is used in the A2FSI.
So the Bosch Motronic implementation of the mapped cooling could well be different.
Same basic theory, slight differences in hardware.
The G2 coolant temp sensor connects to the climate controller too, so I'm off searching for sack cloth and ashes.
Next door has a wood burner, so I'm halfway there ...
Mac.
 
PlasticMac said:
Well, I may be looking at recanting, (surely not?).
Looking very closely at the switch I thought operated the mythical valve, it has a symbol alongside what looks like a potentiometer. Anyone recognise the symbol?
I tried a Google search for the tadpole like image, but no luck. Just hope it doesn't spawn.

Mac.View attachment 105226
Click to expand...
I would guess a variable resistor and perhaps someone has added a T by hand (thermistor symbol not available in their drawing set) so would a thermistor (variable resistor where the resistance varies with temperature) make sense in this context?
J
 
birtyA2 said:
I would guess a variable resistor and perhaps someone has added a T by hand (thermistor symbol not available in their drawing set) so would a thermistor (variable resistor where the resistance varies with temperature) make sense in this context?
J
Click to expand...
Thermistor was my thought too. I was surprised not to find a match with the image search though.
Mac.
 
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