download
1. Use a scan tool to monitor the fuel trim numbers and the Mass Air Flow (MAF) sensor data stream grams/sec readings. Nominal
values are 5 grams/sec at idle in Park, and >150 at Wide Open Throttle (WOT) and 5000 RPM, in gear. Some scan tools have a freeze frame feature, which is useful in trouble shooting if the problem is set at idle versus at cruise. Vacuum leaks and crankcase breather problems generally show up at idle. Voltage at the airflow meter should be .7-.9V at idle and increase from there with more airflow. 2. Monitor the crankcase vacuum with a vacuum gauge, which can be adapted onto the tube for the oil dipstick. Specification for the crank case vacuum is 8 to 15 millibar, this equals about 1/4 to 1/2 PSI or pounds per square. So, 1 PSI of vacuum would be twice as much as there should be at idle. The proper method, per BMW, is to use a slack tube manometer which can be made easily with clear tubing and making it into a U shape and have it marked in inch increments then half fill it with water. When crankcase vacuum is applied to one side of the tubing it should displace 4 to 6 inches of water if the crankcase breather is working correctly. 3. Monitor the fuel pressure. It should be a constant 50 – 53 PSI.
Related posts:
- 2001 BMW X5 3.0i Engine – Valve Cover, Engine Damage in Cold Weather
- 2000 BMW 323I Sport Wagon Check engine light is illuminated in dash
- 2002 BMW 325I 2.5L Check engine light on and fault codes stored
- 1997 BMW Z3 Roadster Cylinder Head Assembly: Service and Repair Engine Installed
- BMW Z3 Repair Manual: Z3 Roadster, Z3 Coupe, M Roadster, M Coupe 1996-2002
