Re: 733 getting too much gas, any ideas? (archive)

Check the ohmic value of the coolant temp sensor at the thermostat housing, will be a blue or white bodied sensor. If the ohmic value is very high with an engine temp that's at least 68degress or better, then you get a too rich mixture from the ECU from the injectors staying open. You'd like to see less than 2000ohms at 68degress, and around 400ohms if you can keep it running until almost fully warm. If the resistance value measured at the 2 pins shows a reading around 8-10,000ohms, then replace the sensor.

Check the ground wires around the intake manifold, some of these can lead back to the ECU or the ignition module.

Make sure the throttle switch is closed all the way, and not stuck open by a mis-adjusted switch. You need an idle signal for the ECU to properly run the injectors when you're actually at idle.

Usually, if the mixture[ CO] measurement is around 8-10% and the fuel pressure is OK, then the ECU or the air flow meter are at fault.
Rarely does much else cause the engine to run so rich.
Try pinching off the cold start injector in case the injector is spraying fuel all the time. The extra fuel hose should be right on top of that earlier "Tube" runner manifold that goes to the "7th" injector on your engine.

Lastly, and this is goofy, try pulling the starter solenoid wire off the starter motor once the engine is running, see if doing so makes the engine run worse, or no change at all. BMW has buried a "start input" on alot of the earlier fuel systems by using the starter solenoid circuit to send a power signal when cranking to the ECU and then the starter becomes a ground signal once the engine is running[ECU sees some resistance through the coil of the solenoid]. If the solenoid coil has too much resistance, it can throw off some ECUs. Not sure if the "L-Jetronic" system on your car had this as the start input like the later Motronic systems did, but worth a shot. I know of at least one 528i with the same system that would run bad and then cut out , all due to a bad starter solenoid, my friend didn't fix that problem until he replaced the starter when it finally wouldn't turn the engine over.

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