Quote (sarge799 @ Apr 20 2014 06:18pm)
Just P0171/0174. No others. Yes I cleared them, they came back quickly. 330i. MAF sensor goes up with revs, picture is idle. Scale doesn't go up to 150... I think I saw around 70 at 4k, can go back and check.
Checked as many intake hoses as I could find, and didn't see anything split on the sides. Mainly looked at the rubber elbow pieces.
It's most likely a bad MAF, it's fairly common on those cars. If you are taking it to a shop I wouldn't go much further. If you are gonna work on it yourself a bit more you should set the tool to graph or display LTFT (Long Term Fuel Trim) and STFT(Short Term Fuel Trim) and watch the Values. Then while it is running grab a can of carb cleaner and spray all around the engine. If you hit upon an air leak you will see STFT drop sharply and probably even go negative. You can also blip the throttle several times while watching the STFT. If it is an unmetered air leak you should expect the STFT to drop to around zero or go slightly negative while around 3000 rpm and return to a positive value at idle.
I went ahead and ran your car + codes through identifix to see the most common causes:
Confirmed Fix
58 - Mass Air Flow (MAF) Sensor
26 - Air Intake Tube
26 - Crankcase Ventilation Control Valve
15 - Crankcase Breather Hose
10 - Differential Intake Air Control Valve (DISA)
6 - Crankcase Breather
4 - Crankcase Breather Hose, Crankcase Ventilation Control Valve
4 - Vacuum Hose/Line(s)
4 - Fuel Pump
2 - Intake Manifold Vacuum Cap
2 - Oil Filler Cap
2 - All Breather Hoses, Crankcase Ventilation Control Valve
1 - All Breather Hoses, Mass Air Flow (MAF) Sensor
1 - Carbon Canister Vent Valve
Tests/Procedures:
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.