Temperature has dropped to about -20 degrees celcius up here, so I have begun using the block heater on my 88 740 T. After using the block heater, if I start the car immediately after unplugging the heater, the engine will turn over, catch, drop to about 300-400 rpm, shudder and struggle for 2-3 seconds or so, then get up to normal idle. If i unplug the block heater at least 5 minutes before starting the car starts normally, as it does when I have not used the heater at all. Not really an issue as I can just unplug the heater earlier, but curious as to why this happens.

I don't know where your block heater is installed, but is it possible that the heater is warming up the temp sensor for the fuel injection and when the car starts it thinks it is warmer than it is. Once the water circulates a little the sensor realizes how cold it is and compensates with more fuel ?

Going farther out on a limb, when you unplug the heater and wait 15 minutes, the plume of warm water thermosiphons past the sensor and pulls some cooler water in behind it. At that point it acts normally.

Greg

Anyone that uses the word "Plume" in a sentence deserves a little recognition.
Happy Thanksgiving
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.lyse.net/brox/TonyPage4.html http://cleanflametrap.com/tony/

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1992 745, >500k km