Hi everyone. I just purchased my first BMW. It's a 1999 323i 5-speed. I'm having some problems with it and I was hoping to find out what could be wrong with it. Recently the check engine light came on and the car had a rough idle. I brought it back to the dealer and he brought it to a mechanic that changed the oil separator valve and the spark plugs. The car seemed to be running fine until a few days later when I turned on the air conditioning. All of a sudden the car started running very rough, it had much less power, and the check engine light came on again. Shortly after I turned off the A/C the check engine light turned off again and the car seemed to be running fine. I brought it to another mechanic who scanned for problem codes. There was a miss fire at all cylinder code in system. They found no problem with the plugs, ignition system, or the fuel system. Fuel injectors were fine. Pressure tested the fuel pump, volume flow test, all were fine. They did some other 22 point inspection... nothing. So he told me to drive it around until the problem started again. On the way home I turned on the A/C and the same problem started. I'm going back tomorrow but I wanted to see if anyone could help me out. Could it be the computer or maybe the fuel pump on it's way out?
There were high pressures building up in the a/c compressor causing it to vibrate. The vibrations were retarding the timing, causing misfires in the cylinders. They switched out the compressor and everything seems to be running fine. I'm really happy that it wasn't bent valves! What's strange is that they told me the compressor in the car was not the factory compressor. That means that the car is five years old and this is at least the third compressor in the car. Is that normal for BMW's to go through a/c compressors that frequently? 
Linear Mode
