OBC 19.7.00 - Watcha' go? doityourself

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Originally Posted by hgrunt

This is normal behavior and partly why BMW makes the needle sit in one spot from 75C-113C. The engine normally runs around 96-98C for maximum efficiency. To avoid overheating if the engine load suddenly increases, the DME can activate a heating element on the thermostat (that connector on top of it) to increase coolant flow. The FSM has a detailed explanation on the Characteristic Map Thermostat, and it's behaviors.

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Yes, this is why the needle on the gauge doesn't move but the OBC shows correct temperature.

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If you want to watch it work, try this: Drive at a steady speed on the freeway once the temp is stable. Floor it for a few seconds in 6th and you should see the temperature drop. After some more steady cruising, it should creep back up to normal.

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Since I've corrected my temperature gauge to show actual temp (middle is between 90-100deg C), I see this behavior often when I downshift to third and let it rip. Whenever the speeds are elevated and the RPMs go up, the temperature drops. On the track my needle will go down as far as the 1/4 mark sometimes (the line before the middle), then it'll go back up to middle once I'm at a steady speed or back in the paddock.

I still don't think BMW should program it to show 75-110 in the middle. They should have just advised owners that it would fluctuate depending on load and temperature. Of course, this doesn't matter anymore since everything is electronic and there no longer are coolant temperature gauges in the new BMWs.

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Originally Posted by hgrunt

This is normal behavior and partly why BMW makes the needle sit in one spot from 75C-113C. The engine normally runs around 96-98C for maximum efficiency. To avoid overheating if the engine load suddenly increases, the DME can activate a heating element on the thermostat (that connector on top of it) to increase coolant flow. The FSM has a detailed explanation on the Characteristic Map Thermostat, and it's behaviors.

In the conditions you were driving it in, chances are it was either creeping past the activation threshold, or the load on the engine changed while it was at operating temperature. It takes my car a few seconds for the temp to drop, so that's probably why it seems random. When I was driving around in Palm Springs in the summer, the car would drop from 96-98C to high 80C whenever I stopped and started moving again.

If you want to watch it work, try this: Drive at a steady speed on the freeway once the temp is stable. Floor it for a few seconds in 6th and you should see the temperature drop. After some more steady cruising, it should creep back up to normal.

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And Welcome H- Grunt!

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Originally Posted by ELCID86

And Welcome H- Grunt!

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Not sure if you have or not Hgrunt, but please introduce yourself and your car in our New Members Section. And, welcome!

Finally did this.

OtterEffect: [2003 3.0L M54 DME-MS45.1] = 93

Does this count? :biggrin

2003 MS45.1, -5°C. That's what you call a cold start.

Attachment 16855

Whammy [2003 3.0L M54 DME-MS45.1] : 96

Taken from Torque.

Numbers are in Celsius, once plateau is reached.

Oli77 [2005 2.5L M54 DME-MS45.1] : 96
Danewilson77 [2004 3.0L M54 DME-MS45.1] : 95
Telijah [2001 3.0L M54 DME-MS43] : 88 (suspects open T-stat)
edlvrt [2004 3.0L M54 DME-MS45.1] : 96
MrMaico [2004 3.0L M54 DME-MS45.1]: 96
Spencers [2001 2.5L M54 DME-MS43] : 90
LivesNearCostco [2003 3.0L M54 DME-MS45.1] : 91 (old T-stat)
LivesNearCostco [2003 3.0L M54 DME-MS45.1] : 95 (new T-stat)
derbo [2004 3.0L M54 DME-MS45.1] : 95
GT172I [2004 3.0L M54 DME-MS45.1] : 96
shanneba [2003 3.0L M54 DME-MS43] : 89 (running water wetter and stewart pump)
Hochspannung [2005 3.0L M54 DME-MS45.1] : 87 that's the outlier, unless these are the M car values.
Kayger12 [2005 3.0L M54 DME-MS45.1] : 95
RITmusic2k [2004 3.0L M54 DME-MS45.1] : 83 T-stat work ongoing
terraphantm [2003 3.0L M54 DME-MS45.1] : 95
Hermes: [2005 3.0L M54 DME-MS45.1] = 95
328ioc: [2005 3.0L M54 DME-MS45.1] = 95
WOLFN8TR:[2005 3.0L M54 DME-MS45.1] = 90
pip: [2005 3.0L M54 DME-MS45.1] = 97
Johnrando: [2006 3.0L M54 DME-MS45.1] = 94
Meric: [2004 3.0L M54 DME-MS45.1] = 98
Nivo: [2004 3.0L M54 DME-MS45.1] = 95
NorCalZman: [2005 3.0L M54 DME-MS45.1] = 94
Blaster3500: [2007 335i ? dudes in the know can fill this in please] = 95
OtterEffect: [2003 3.0L M54 DME-MS45.1] = 93
Whammy [2003 3.0L M54 DME-MS45.1] : 96

Keeping it clean.

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Originally Posted by alexandre

Does this count? :biggrin

2003 MS45.1, -5°C. That's what you call a cold start.

Attachment 16855

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Gawd!

I FINALLY got my cooling system overhauled and the new thermostat installed. Sure enough, she's operating exactly as she should now... I'm seeing temperatures snap up to 95º within minutes and then it stays right there. I've already noticed my city MPG has gone up by a good 2MPG.

Hi Riker! Good to see you in the old temperature thread. And thanks for the bump!