Anonymous asked in Cars & TransportationMaintenance & Repairs · 2 months ago

Why did my spare MAF sensor cause the car to have sluggish acceleration and rough idling (MAF sensor was cleaned prior to me installing it)?

I was looking at ways to improve my spare car, a 1998 BMW E46 323i, by replacing the existing MAF sensor with my spare I got from a wrecker, replacing the ignition coils and plugs, replacing the filters and fluids. The car did run fine without the sluggish acceleration and surging/rough idle for some time with the cleaned MAF sensor, but these problems eventually came within a month of installing it and doing a major service.   I can also smell unburnt petrol before I did a major service.

If it helps at all, my spare MAF sensor was cleaned inside my house where a deep fryer had allowed smoke and oil to reach the ceiling.   I'm also getting a few error codes from my scanner stating something about a "fuel trim" 

Rough/surging idle and sluggish acceleration went away after cleaning and  installing the previous MAF sensor. 


My scanner had picked up a few error codes relating to something about fuel trim. I can also smell unburnt petrol even after cleaning the MAF sensor. 

1 Answer

  • 2 months ago
    Favorite Answer

    The answer is simple. If cleaning it isn't working then you need to replace the MAF sensor. I wouldn't suggest a junk yard sensor either. It is possible that it may still run if you simply unplug the sensor, until you can get a new one. Some will still run with it unplugged and some wont. Good luck.

Still have questions? Get your answers by asking now.