In Reply to: Is 17mpg OK? posted by Artem Grigoryev on January 30, 2001 at 09:04:31:
So in short, check your O2 sensor. If you have a multimeter, consult your Bentley manual on how to check the sensor.
Also, there are 3 solder joints inside the ECU (engine control unit) that go bad over time. Open it up and you'll see a large round transistor on the side. It has 3 jumper leads soldered to the board. The joints on the board come loose, and that weakens the spark. This KILLS the power, and you'll open up the throttle more to compensate, hence the poor fuel economy. Common problem among 80s BMWs. Resolder with good lead-free solder. Radio Shack sells a small tube of 94% tin 6% silver rosin core solder for about $2. A 15/30W switchable soldering iron is $10.
Another problem may be your air-flow meter crapping out, but that is less likely than the other two problems. If so, you'll need a good used one to borrow for comparison.
Check these and let us know what you find.