At this time the car runs great when started and after letting it idle for a seemingly unlimited amount of time. Even after taking to the road all the power is there and idle is normal until the car is driven for about 15 minutes or more. Then the idle gets very rough and power is lost unless the peddle is pressed to about the 3/4 full position, at which time the engine will clear up and power comes on. When idling, it gets rough and the exhaust becomes very rich and dark.
I have begun to suspect that something on the engine is not acting correctly at temperature. I removed the Oxygen sensor heater relay and the core seems to run much better. Actually I'm not fully sure if the car is running better tonight because it is cooler outside, or because I have removed the Oxygen sensor heater relay.
Does anyone have any thoughts on this?
Also, Does anyone know how to remove the connector for the Air Intake sensor? I have never removed it, and don't want to break it. How do you check for 5 volts between the supply voltage wire and ground while the harness is connected? Or are you supposed to disconnect the harness?
When I look in the Aux Relay Panel there is a red wire that appears to have been cut. Does anyone know what this wire goes to?
Also, when the engine is running bad, I would expect to get a check engine or EML light. I don't and wonder if the engine management system is recognizing that the engine is not running correctly. I have tried to get the codes from the OBC computer by pressing the gas peddle 5 times, but this has not affect. Can anyone tell me why I can't get codes from my OBC?
Your help is greatly appreciated!
Keith '88 750il