m42cal
06-18-2012, 04:40 PM
I have been having power hesitation problems on my 1994 318is. i have cleaned the mass airflow sensor, the idle control valve, and I replaced the O2 sensor last year. I also replaced the valve cover gasket and spark plugs hole seals after discovering lots of oil in one of the spark plug wells. The car is running better now, however, there is a loss of power, and the car almost shuts off with a low idle, when the engine temp is 1/2 way between cold and normal operating temp and this causes the the 1215 mass air flow sensor fault code. When the engine is cold or at operating temp, it seems to be running normally, although I can't test drive it completely as I'm concerned it may lose power.
The Bentley service manual suggests testing the mass airflow sensor resistance across pins 1 and 5 (I also tried 2 and 5 after reading other posts) and the manual says the resistance should change as the air inlet door is moved through its travel range. I tested it and the resistance does not change when I move the vain/door through all its travel with the sensor disconnected. However, the when I test the voltage across the same pins mentioned above with the sensor connected and the ignition on, the voltage changes when I move the door. This means to me that a signal is being generated when airflow is changing, although I could be wrong.
There seems to be no way to buy a used, rmfg, or new air flow sensor and then return it if it does not fix the problem as all the sellers do not allow returns if the sensor has been installed. I'm a student and didn't want to buy a new airflow sensor if it may not solve the problem.
Any comments would be appreciated. Thanks!
The Bentley service manual suggests testing the mass airflow sensor resistance across pins 1 and 5 (I also tried 2 and 5 after reading other posts) and the manual says the resistance should change as the air inlet door is moved through its travel range. I tested it and the resistance does not change when I move the vain/door through all its travel with the sensor disconnected. However, the when I test the voltage across the same pins mentioned above with the sensor connected and the ignition on, the voltage changes when I move the door. This means to me that a signal is being generated when airflow is changing, although I could be wrong.
There seems to be no way to buy a used, rmfg, or new air flow sensor and then return it if it does not fix the problem as all the sellers do not allow returns if the sensor has been installed. I'm a student and didn't want to buy a new airflow sensor if it may not solve the problem.
Any comments would be appreciated. Thanks!