'85 325e has strange idling problem

[ironman502]

I recently bought this car at an auction-it has 236k miles or so. Occasionally, when the car is idling, (like at a stoplight) the engine will begin to hunt. Then, the second I touch the gas pedal, the revs drop to about 200 rpms and the car misses and smokes like crazy. Of course, any attempt to move the car under it's own power (it is a 5-speed) will instantly kill the engine, so I have been stuck with drivers honking at me several times now. After letting the engine rev for about five minutes, it will stop misfiring and begin to run normally again. A friend of mine thought it was the intake bellow, but it checked out fine. The engine's temperature has no effect on when this happens, and there is no loss of power before it acts up. Any help would be greatly appreciated; I love driving my BMW, but it's quite dangerous in this condition. Thanks for reading.

[KC Ron Carter]

I have owned a 1984 325e since new.

In the 90s BMW did a recall to prevent the passengers from being burn by coolant should the heater lines burst.

They installed a brass valve in the coolant lines to the throttle body heater. The power was parasited from the ECU coolant sensor.

As the valve gets older the valve can cause what you see.

The connector for the valve is exactly the same as a 30 amp green spade fuse. Install a fuse in the connector and see if this fixes it.

If that fails replace the ECU coolant sensor.

Later,

[ironman502]

Thank you! I will try what you said.

We just got 5 inches of snow, and my 3-series has bald rear rubber, so I'll have to wait until the roads are clear to see if your recommendation works. (A 17-year old like me doesn't have money for sand bags, let alone snow tires!) Thanks again.