Recently had an issue arise on my 2005 A4 1.8T. Had the CEL on so i went to have it checked and it had P0722 (Output Speed Sensor), P0303 (cylinder 3 misfire), P0171(Bank 1 too lean) & P0101 (Master volume air flow circuit range). The guy at Orileys pulled all those codes and then cleared them. I left and didn't even get a quarter mile down the road and my car just dies. Tried to restart it several times and it wouldn't run for more than 4 seconds.
Get it back to my shop thinking the misfire turned into a dead cylinder so i bought a new coil pack with no luck. Replaced the spark plugs in the mean time since they where due. Checked for popped hoses (since the boost tube had popped off before) and can't notice anything. Had a buddy come by and look at it and told him what was going on and he said it might be the MAF due to the P0101 code, so I get a new one and still doesn't run. I unplug the MAF for ***** and gets and it runs without it unplugged. It seems like it runs even better without the MAF plugged in since I've owned the car. Drive it down the road and seems fine (been told you shouldn't drive them without it plugged in though). So I take it to a local shop that is known for dealing with foreign cars and he looks it over, checks the wires, tested another MAF on the car and nothing. He told me it might be the computer, something about the reading of the MAF or something and that it might have to be reflashed. Wanted to see if anyone else might have any suggestions?

 

When you unplugged the MAF you foced the ECM into open loop mode, which means it is ignoring most sensors and runnining on predifined A/F tables. This is an indication that one of the sensors among those being ignored (and not necessaraly the MAF) is generating bad data. The P0101 code points to the MAF, and being that replacing the MAF did nothing you need to look at the wiring between the MAF and ECM. If the wiring is OK ,you should look at all sensors with a scanner and verify the data seen by the PCM makes sense.

 

The wiring seems fine running to the ECM. Could it be possible (even though I dont see the need to) before installing the new MAF I needed to unplug the battery to tied the two cable together to let the capacitors drain to reflash the ECM?