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// Quandt AG (Retired) //
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Discussion Starter #1
I'll just throw this out there. For several years I've been monitoring live data on my e46's. Started out (thanks to JFOJ) simply using OBD Fusion to keep a live display on my dash of the ECT (Engine Coolant Temp). Since then it has progressed to a point where every time I drive a BMW (e46, e9x, e83, F30 etc.) I log the data - setup mostly relevant to the cooling system.

For this winter I am driving a vehicle (2003 325xi) I have never previously driven in winter. The logged data so far is consistent with prior logs from a wide range of e46's, mostly the ones I've owned and some that I've had opportunity to drive.

I review the live data logs for several reasons - mostly related to identifying DME cooling system logic.

I thought I'd share a sample log from this vehicle from yesterday. Why? Well this short log is very telling of many of the things that get asked around here all the time. I'm not saying that this single log is definitive - it is but one log, but I do know that the values are almost identical and typical of the values I've encountered in all the other e46's I've logged. What I like about this log is the car is completely stock. It is also automatic - a rarity for me to drive as all the e46's I've owned have been manual, but no doubt very similar to many of the folk on here who drive stock setups in an automatic.


On to the quiz. If you look at this log you can tell the following (about this vehicle):

Questions:

1. The temp never reached 97C during the entire test cycle - During the test cycle is the thermostat ever open or always closed? How can you prove it?

2. At what threshold and what parameter decided to signal DME to activate the electric fan? Was the DME decision impacted by the temp at ECT or oil temp? How can you prove that?

3. At what threshold and what parameter decided to signal the electric fan to shut-off. Was that DME decision impacted by ECT or oil temp? How can you prove that?

I was gonna add a 4th question regarding the t-stat heater voltage but it would have been a trick question as it was never active during the test cycle as verified by the live data so I just dropped that column.

Tips:
I've made it easy by color coding areas of the log where the answers will be found. You will also benefit from knowing the the e-Fan PWM signal value of 5.07819 means the e-fan is stationary.

Have fun.
 

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I can tell that you need a simple analysis program!
Digging through raw logs like that by hand is a sure sign that you're nuts!!!
(or that you'll drive yourself there...)

But playing along...
Of course the t-stat opens- the lower hose temp goes to 90.
Your t- stat's holding about 91, by the looks of things.
But the fan responded to the rise in revs- did you floor it?
And it shut off when the lower hose went below 80.
I log TPS, but I'm paying attention to
different performance characteristics, like top speed at the end of the
front straight, or how much I have been rolling onto the throttle how early in 2...

t
codes his in C++
and yet, still is nuts.
 

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1) the thermostat did open. The proof: CTS would not get to 90 if no coolant flow through radiator with closed thermostat.

2) fan turned on by CTS at 85.5C or higher, and not depending on ECT nor oil temp b/c when it started turning on neither oil nor ECT was changing value.

3) fan off when CTS is 80.25 or lower. not impacted by oil nor ECT bc neither values were changing when fan moved from on to off.
 

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// Quandt AG (Retired) //
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Discussion Starter #5 (Edited)
OK Good. Thank you Sapote and TobyB for joining in. (Toby - yes I use analysis tools but here I wanted to post the full log so there is no claim the data was manipulated). I also used this specific vehicle log as it is relatively short but shows a classic e46 working perfectly cooling system that employs DME logic exactly as all my other logging efforts have proved.

I actually think you both did well (made it easier color coding the sections I bet) but you both realize however that your acknowledging certain conditions (events) that will fly controversially on this forum?



You both confirmed the following:
Questions:

1. The temp never reached 97C during the entire test cycle - During the test cycle is the thermostat ever open or always closed? How can you prove it?


Answer:
Yes - of course the thermostat was open despite the fact the temp never exceeded 92C the entire test. The thermostat was wide open several times - how can that be proved - well at one point the temp at CTS was higher than ECT. That could not occur unless the coolant was free flowing through the rad and engine.

I didn't ask this question but at approx what temp did the t-stat start to open. Well seeing you only had one log it would have been unfair. But when you compare the data over hundreds of logs from different vehicles you can determine that approx value by the relationship between ECT & CTS. In this log you can see the rapid increase (curve) of the CTS temp is occurring @85C ECT. The flow of hot coolant starts to effect CTS (reducing the gap to ECT) as the thermostat starts to open.


2. At what threshold and what parameter decided to signal DME to activate the electric fan? Was the DME decision impacted by the temp at ECT or oil temp? How can you prove that?

Answer:
You both did well (although I color coded the exact lines where this answer could be found). In fact, from a wider analysis I will confirm that the CTS value of 85C will signal DME to activate the e-Fan. When the temp drops below 80C DME will reduce the PWM signal below the threshold for e-Fan activation. (it maintains a base signal for comm purposes)

Is DME impacted by the oil temp or ECT temp in the e-Fan decision - NO - the log shows radically different values for both those parameters at different times throughout the log at points of activation. What will effect the value of the e-Fan PWM signal? - again demonstrated clearly in this log, is the effect that vehicle speed plays on the speed of the e-Fan. There are other parameters that DO impact the final DME assigned e-Fan speed (AC, Battery Voltage etc.) but they were excluded from this test.

3. At what threshold and what parameter decided to signal the electric fan to shut-off. Was that DME decision impacted by ECT or oil temp? How can you prove that?

Answer:
See answer above for #2.


What was the point of this quiz?
Well this log was one of those that was perfect. First, it is relatively short. The car is stock everything. It has a brand new (wahler) thermostat installed 3 weeks ago, and the parameter values that I'm seeing are the same values that the 5 year old (Behr) it replaced effected. It has a Saleri water pump (Nov. 2018). It has a new Heater valve (Nov. 2018). All the temperature sensors report good and are OE. The Bosch e-Fan surpassed the INPA test. It is automatic so my driving style really wouldn't effect the RPMs. For all intents, this e46 is the perfect specimen for testing, unlike some of my others that have aftermarket (Stewart) water pumps and different e-Fans (Mazda, Volvo) and are manuals.

What Sapote and TobyB confirmed is that on a perfectly working e46 cooling system the thermostat is well open way before the ECT has reached 92C.


On older cars with single stage thermostats the value stamped on the flange was typically the temp at which the thermostat started to open. How can 97C be the temp the thermostat starts to open???? Why do folk think that 97C is the normal op temp - probably cause it's stamped on the 2-stage thermostat. But why can't that be the value for stage-2?



The data (and I don't mean just this log) - I have hundreds that demonstrate similarly from 10 e46's, clearly indicate that the thermostat is starting to open @85C or thereabouts. By 90C it is often wide open as this log illustrated. I think this engine has a normal op temp range - much lower than most believe.

So here's the final question:

If you believe the normal operating temperature range of this engine starts greater than 95C - Prove it!


You can do this by showing logs that dispute the findings posted here. Gather data that demonstrates different setpoints in DME logic. Post data that shows DME reactions at higher temps. Post different documentation. anything. Just don't say cause the thermostat says 97C. If nothing, this quiz proves the stock thermostat opens well before 97C - actually it was wide open before 92C.

I do not believe that 97C is the "normal operating temperature" for this engine. DME logic setpoints (posted in table below) seem to support a much lower normal temperature range. Think about this for a minute - IHKA shuts the heater valve at 80C to protect the heater core. If the HCT temp reaches 93C DME invokes emergency stage-2 thermostat cooling. We've confirmed that CTS activates e-fan OFF and ON at 80/85C - a normal range with ECT at 97+C would see the e-fan running almost all the time your speed dropped below 25 km/h, the Heater valve would get shut off frequently >80>93 - this doesn't happen.

There is the impact of ambient temps. I have noted that in winter logging if I manipulate the heater valve closed, that immediately upon opening it, ECT drops 1-2C - as expected. But within 2-3 minutes has stabilized back to the pre HV open ECT temp as the cold coolant in the heater core is absorbed into the main coolant that circulates the engine and rad. Occasionally, especially on summer logging I've seen ECT temps rise to 95-96C (excess load, AC=ON, high ambient temp, Zero speed etc.) - but as an exception, not as a rule - in short time I also see DME react to those increased temps by increasing cooling capacity via the e-Fan or natural air cooling via increase vehicle speed to restore the temp range.

BMW's replacement engine to the m5x (N52) is much more forthcoming with published info and data (I've done extensive logging on that engine). On that engine BMW confirm the thermostat starts to open at 85C and the normal temps are a range and not a set point. DME also controls coolant temps better by controlling the speed of the electric water pump. Unlike the e46 m5x, DME will shutoff the engine in an N5x when temps reach a critical threshold.

In summary, I don't think there is a single set temp at which this engine can consider normal operating temp. I think it is a variable target within a range (like the n5x) based on sensor inputs. I also think that overall range is much wider and starts lower than most believe. My belief is that this thermostat starts to open around 85C and most temperatures fall in between 88-93C (variably effected) and a range up to 95C is most common.

I encourage others to do similar analysis. If you do your own tests determine the normal operating temp range - not the temp sitting idling in your driveway with an OBD device connected or the engine cluster readout. The ECT temps during those conditions will not show you your normal operating temp range - just your idling temp - Why? RPM's are reduced - so you've reduced the flow of coolant - the temp diff in CTS and ECT will be effected, meaning CTS may be high then drop and ECT will climb - you're only reading ECT - the e-Fan will come on later with the lower temp due to the slower moving coolant - Eventually CTS will hit 85C and the e-fan will quickly drop the temps - that's exactly what the logs have shown. That is probably not an effective way to determine normal operating temperatures (all modes). You'll get a truer representation by gathering a lot of data from different points and when the vehicle is operating, idling and moving at various speeds.

 

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I***8217;m new to e46***8217;s and DIYing but aren***8217;t questions 2 and 3 trick questions since automatics come with clutch fans not electric ones!

I have an automatic with electric fan though since I converted it so I***8217;m assuming this one was converted so I***8217;m just kidding around.
 

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// Quandt AG (Retired) //
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Discussion Starter #8
As I mentioned I was just kidding around. Love the work you and everyone else puts in. It’s very much appreciated.
I realize you were adding levity but there is NO automatic to manual electric fan conversion It is merely a mechanical fan delete.

Your automatic came with an electric fan that operates on the exact same DME e-fan logic, set points and thresholds - which if you think about it - is why you can truly remove the viscous clutch fan and just operate on the existing e-Fan. Also why you can use the exact same components interchangeably between the different shrouds.

Some choose to move the e-Fan on the other side of the rad to emulate the manuals but that isn't really necessary. Probably more for efficiency and aesthetics. If DME needed more air (cooling)- it will just spin the e-fan faster and more often left on the front side of the rad. That is the brilliance of DME cooling logic.
 

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I'm new to e46's and DIYing but aren't questions 2 and 3 trick questions since automatics come with clutch fans not electric ones!

I have an automatic with electric fan though since I converted it so I'm assuming this one was converted so I'm just kidding around.
Automatics come with both the mechanical clutch fan AND electric fan.
 

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Some interesting insight here. Perhaps we could plot all those values in Excel.
A question for the learned (politely hijacking the thread)

I believe my M3 has a failed Oil Level Sensor. The yellow oil can symbol hangs around for some time after start up but it does go off. The oil temp guage shows low actually no oil temp - same OLS sensor presumably. I'm limping along on the manual mechanical Oil Level Indicator until next oil change.
Buffered coolant temp is sticking to its normal routine of always climbing to an indicated normal well ahead of the oil temp when it worked - nothing has changed there.

Warming up the yellow and red lights around the tacho always seemed to follow the oil temp not the coolant temp when they're not telling me to shift. They still do follow the oil temp -or do they? I've assumed they were driven from the OLS but it seems not as they still work. Where is this backup oil temp sensor or is the the ECT sensor wherever that is what drives the tach lights?
Back to the thread, should an M3 follow similar logic? I don't remrber wires on the thermostat.
 

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// Quandt AG (Retired) //
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Discussion Starter #12 (Edited)
Some interesting insight here. Perhaps we could plot all those values in Excel.
A question for the learned (politely hijacking the thread)

I believe my M3 has a failed Oil Level Sensor. The yellow oil can symbol hangs around for some time after start up but it does go off. The oil temp guage shows low actually no oil temp - same OLS sensor presumably. I'm limping along on the manual mechanical Oil Level Indicator until next oil change.
Buffered coolant temp is sticking to its normal routine of always climbing to an indicated normal well ahead of the oil temp when it worked - nothing has changed there.

Warming up the yellow and red lights around the tacho always seemed to follow the oil temp not the coolant temp when they're not telling me to shift. They still do follow the oil temp -or do they? I've assumed they were driven from the OLS but it seems not as they still work. Where is this backup oil temp sensor or is the the ECT sensor wherever that is what drives the tach lights?
Back to the thread, should an M3 follow similar logic? I don't remrber wires on the thermostat.
Never owned an e46 M3 but if I recall the info Terra posted your M3 doesn't have wires to the thermostat - yours is a 1-stage thermostat and is stamped 80C.

Not sure there is a physical backup oil temp sensor on the M's. The non m's have a sensor on the OFH that is listed as an oil temp sensor on realoem. However I have no idea if that is used primarily or as a backup - it very well may be since the location is perfect for that. It's a different engine but the N5x documentation states that if the OLS fails that DME will use CTS as a substitute value. It's feasible on that engine due to CTS location (head) but not on the M5x (lower rad). Perhaps the M's use ECT as a substitute value?

I'm surprised that you haven't modified the buffered temp gauge - IMO that is the best mod that one can do to this chassis.

Edit: Just saw your question about whether the M3 should follow the same logic. My gut response is NO. I recall Terra posting stuff about the difference in DME logic for the M3. The decision processes might be similar but the thresholds and set points are radically different. Your M3 received a more powerful e-Fan I think, manuals had viscous clutch fans, you have no electronic thermostat control - even your buffered temp gauge has different values.
 

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You get the oil temperature from the oil level sensor in the sump. You can tell by the slow rising and slow descending temps that the temperature is not conducive to high fluctuation that you would get from a channel sensor. I posted about this in another thread. It is on PIN 3 which communicates Oil Level and Oil Temp.
I also posted the PID address values in another thread on here recently.

No idea what the oil temp sensor by the OFH does - anybody know? The e46 M's don't have a sensor there - they get the oil temp from the OLS also.

It would be great if other folk could log the exact data across the continent, and post it, that would give a wider raw data set to analyse. I've only logged data in Ontario and South Carolina and the states in between and the vehicle count is only 10 e46's. Still - every one of them is basically consistent. DME set-points are DME set-points - they are digital values - not variables. They are what they are. The only times the logged values go askew is when something isn't working properly (failing wp impeller, bad e-fan, soft fail t-stat, failing sensor etc.)
Non-Ms actually pull the oil temp from the sensor on the filter. M3 pulls it from the level sensor.

Never owned an e46 M3 but if I recall the info Terra posted your M3 doesn't have wires to the thermostat - yours is a 1-stage thermostat and is stamped 80C.

Not sure there is a physical backup oil temp sensor on the M's. The non m's have an added sensor on the OFH that is listed as an oil temp sensor on realoem. However I have no idea if that is used as a backup - it very well may be since the location is perfect for that. It's a different engine but the N5x documentation states that if the OLS fails that DME will use CTS as a substitute value. It's feasible on that engine due to CTS location (head) but not on the M5x (lower rad) so maybe you just figured out what that extra sensor on the non M OFH is for. Perhaps the M's use ECT as a substitute value?

I'm surprised that you haven't modified the buffered temp gauge - IMO that is the best mod that one can do to this chassis.

Edit: Just saw your question about whether the M3 should follow the same logic. My gut response is NO. I recall Terra posting stuff about the difference in DME logic for the M3. The decision processes might be similar but the thresholds and set points are radically different. Your M3 received a more powerful e-Fan, manuals had viscous clutch fans, you have no electronic thermostat control - even your buffered temp gauge has different values.
Ms and non-Ms have a block coolant temp sensor and a coolant outlet temp sensor. Iirc the M3 does attempt to calculate oil temp based on input from multiple sensors if the oil level sensor fails.

M3 coolant temp gauge has a small buffer from the factory, not really necessary to modify it. M3 efan isn***8217;t any more powerful, just shaped differently to clear the oil cooler.
 

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// Quandt AG (Retired) //
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Discussion Starter #16
Non-Ms actually pull the oil temp from the sensor on the filter. M3 pulls it from the level sensor.
Again I stand in awe Terra. I just disconnected the oil temp sensor on the non m OFH and tried to log - it defaulted to -48C This must be the only model that doesn't use the OLS for both (exact same part on my e83, e90 & e92) to provide the oil temp. M5x can't use CTS as a backup - is it OLS or the ECT?

I should refrain from any comments on S54 but I coulda swore you stated years ago that the m3 fan was a higher wattage? Thanks for the corrections.
 

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Z4M (which also has an s54) has a 600w puller fan with no mechanical unit. M3 goes with the 400w(?) pusher fan plus a mechanical puller fan. Unfortunately the z4m fan is too thick to fit the e46 m3
 

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Okay, this is how the thermostat on the stock M54 engine works:

As you all know, there are 2 modes.

First mode: The thermostat opens due to the temperature of the coolant passing through it and heating up the wax element that expands via phase change from solid to liquid. The thermostat starts to open at about 95C and is fully open about 100C or thereabouts. At 97C, the thermostat is roughly one-third open.

Second mode: The DME sends electric current to the heating element that heats the wax. In this mode, the thermostat opens fully whenever the DME sends 12 volts to the heating elements for a few seconds. In this mode, the temperature of the thermostat does not matter directly at all. It will open FULLY at 80C, or 85C, or 90C, or any temperature, whenever the DME sends current to the heating element.

Let us perform some thought experiments.

First, let us unplug the heating element to the thermostat. What do we have? A purely "mechanical" thermostat that opens at about 95C and operates at 97C or thereabouts. Below 95C, the thermostat is closed. Above 99C or 100C, it is fully open.

Second, re-plug the heating element. What do we have? A strange hybrid thermostat. For light driving, you could drive for miles without the DME sending any current to the heater, so the thermostat opens at 95C and your engine will hum along at 97C coolant. HOWEVER, as soon as you step on the gas any harder than the "weight of a cigarette paper," the DME will send 12 volts to the heating element on the thermostat for several seconds, fully opening the thermostat. So at that point, the coolant temperature rapidly drops from 97C to 90C or 85C or somewhere in that range. Note that there is NO PRECISION to how much the coolant temperature will drop. The thermostat will open fully within seconds from the heating current, and the coolant temperature drops rapidly within seconds, but the DME can only control the DURATION of the heating current (always just a few seconds) and has NO PRECISE CONTROL at all over how much the coolant temperature will drop.

I hooked up an LED light to the wires that go to the heating element on the thermostat. The LED "blinks" on for a fraction of a second about every second ALL THE TIME while you drive. This is the signal that tests whether the DME is connected to the heating element. The signal does not stay long enough to heat the element. But when you drive in a spirited manner, the LED stays on for several seconds at a time and turns off, going back to the "blink" every second. Within SECONDS, the coolant temp goes down from 97C to 90C or even 85C, and then gradually rises to 97C over several MINUTES.

If you disconnected the heating element wire, the thermostat would stay at 97C all the time, except for brief moments when it goes up to 100C or so due to stepping hard on the gas pedal.

Note that when the DME sends the heating current to the thermostat, the thermostat is NO LONGER operating in the manner of a traditional thermostat that opens or closes at a certain temperature range. The thermostat opens fully at ANY TEMPERATURE as long as the DME sends the heating signal. The DME sends the signal to heat the thermostat wax element when you step on the gas pedal hard, basically.

All of the above points may be obvious, but it is really informative to have an LED light hooked up to the heating element wires, and see how that light corresponds to the coolant temperature, which I can read off my Ultragauge. There is ABSOLUTELY NO MYSTERY to the behavior of the thermostat and the behavior of the coolant temperature once you have conducted this experiment.

The bottom line is that you could drive all day with the foot on the gas pedal very lightly (still maintaining speed limit) and the "normal" would be 97C all day. (That is to say, when the DME sends no heating current)

Or you could drive in a spirited manner and the "normal" would be widely swinging temperature that ranges from low 80s to mid 90s and above. (That is, when the DME sends heating current repeatedly).

But from the "thermostat's point of view," the thermostat will always start opening at 95C, and is about one-third open at 97C, and is fully open around 100C or thereabouts. It is just that the heating element powered by the 12V from the DME "fools" the thermostat to think that it is above 95C even when the coolant temperature may be much lower. Or if the DME sends 12V with the coolant at 97C, then the thermostat goes from 1/3 open to fully open, thus dramatically lowering the coolant temperature to 85C or 90C or somewhere in that range.
 

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// Quandt AG (Retired) //
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Discussion Starter #19
Okay, this is how the thermostat on the stock M54 engine works:

As you all know, there are 2 modes.

First mode: The thermostat opens due to the temperature of the coolant passing through it and heating up the wax element that expands via phase change from solid to liquid. The thermostat starts to open at about 95C and is fully open about 100C or thereabouts. At 97C, the thermostat is roughly one-third open.

Second mode: The DME sends electric current to the heating element that heats the wax. In this mode, the thermostat opens fully whenever the DME sends 12 volts to the heating elements for a few seconds. In this mode, the temperature of the thermostat does not matter directly at all. It will open FULLY at 80C, or 85C, or 90C, or any temperature, whenever the DME sends current to the heating element.

Let us perform some thought experiments.

First, let us unplug the heating element to the thermostat. What do we have? A purely "mechanical" thermostat that opens at about 95C and operates at 97C or thereabouts. Below 95C, the thermostat is closed. Above 99C or 100C, it is fully open.

Second, re-plug the heating element. What do we have? A strange hybrid thermostat. For light driving, you could drive for miles without the DME sending any current to the heater, so the thermostat opens at 95C and your engine will hum along at 97C coolant. HOWEVER, as soon as you step on the gas any harder than the "weight of a cigarette paper," the DME will send 12 volts to the heating element on the thermostat for several seconds, fully opening the thermostat. So at that point, the coolant temperature rapidly drops from 97C to 90C or 85C or somewhere in that range. Note that there is NO PRECISION to how much the coolant temperature will drop. The thermostat will open fully within seconds from the heating current, and the coolant temperature drops rapidly within seconds, but the DME can only control the DURATION of the heating current (always just a few seconds) and has NO PRECISE CONTROL at all over how much the coolant temperature will drop.

I hooked up an LED light to the wires that go to the heating element on the thermostat. The LED "blinks" on for a fraction of a second about every second ALL THE TIME while you drive. This is the signal that tests whether the DME is connected to the heating element. The signal does not stay long enough to heat the element. But when you drive in a spirited manner, the LED stays on for several seconds at a time and turns off, going back to the "blink" every second. Within SECONDS, the coolant temp goes down from 97C to 90C or even 85C, and then gradually rises to 97C over several MINUTES.

If you disconnected the heating element wire, the thermostat would stay at 97C all the time, except for brief moments when it goes up to 100C or so due to stepping hard on the gas pedal.

Note that when the DME sends the heating current to the thermostat, the thermostat is NO LONGER operating in the manner of a traditional thermostat that opens or closes at a certain temperature range. The thermostat opens fully at ANY TEMPERATURE as long as the DME sends the heating signal. The DME sends the signal to heat the thermostat wax element when you step on the gas pedal hard, basically.

All of the above points may be obvious, but it is really informative to have an LED light hooked up to the heating element wires, and see how that light corresponds to the coolant temperature, which I can read off my Ultragauge. There is ABSOLUTELY NO MYSTERY to the behavior of the thermostat and the behavior of the coolant temperature once you have conducted this experiment.

The bottom line is that you could drive all day with the foot on the gas pedal very lightly (still maintaining speed limit) and the "normal" would be 97C all day. (That is to say, when the DME sends no heating current)

Or you could drive in a spirited manner and the "normal" would be widely swinging temperature that ranges from low 80s to mid 90s and above. (That is, when the DME sends heating current repeatedly).

But from the "thermostat's point of view," the thermostat will always start opening at 95C, and is about one-third open at 97C, and is fully open around 100C or thereabouts. It is just that the heating element powered by the 12V from the DME "fools" the thermostat to think that it is above 95C even when the coolant temperature may be much lower. Or if the DME sends 12V with the coolant at 97C, then the thermostat goes from 1/3 open to fully open, thus dramatically lowering the coolant temperature to 85C or 90C or somewhere in that range.
This is why I posted the raw logged data. This is complete conjecture and actually hysterically funny unless someone were to believe it. In a properly working cooling system the tstat is rarely commanded on except when one of the documented conditions exist. BTW you can’t just monitor the tstat with an LED to figure it out. You should monitor all the inputs that would trigger DME to open it. ECT has to reach 112C or IAT 52C, HCT 93C etc. That’s published info not mine.

10 e46s, hundreds of hours of logged data and I’ve only seen tstat signal on a few times when IAT reached threshold, and once when I left a fan unplugged. If you’re running ECT 100C + most of the time sounds like you’re approaching an overheated condition. Watch those extreme temps do not anneal the head.
 

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OK. From someone who is an E46 newbie but heard all the horror stories of e46 cooling system weaknesses, I rebuilt my entire cooling system (2005 330Ci A/T vert with 60K miles) except for radiator. Recoded temp gage per Terraphantom. Given all this info, I still have some angst when driving about temp getting to 99 or 100 via hidden OBD OR watching temp gage needle inch past 12 on occasion when idling at a light but drop almost immediately. To my knowledge electric fan works fine but I have no sure way of knowing. Is my angst when hidden OBD shows temp at 99C much ado about nothing? I never see any large temp excursions on hidden OBD or gage. In fact only at idle do i ever notice obd at 100 or 101 and it immediately goes down on its own when i move and/or when electric fan kicks in (I think). So am I to conclude my car is operating "normally". I don't have OBD Fusion but have thought about purchasing. Living in central FL I know it will be hot in summer and I will be at stop lights idling at times. Would rather not have my pulse rate elevate everytime I see gage go past 12 even for a few seconds.
 
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