A4 1.8T -2000 & MAF sensor

MAF sesnsor problems are various. Typically there isn't any trouble codes when MAF sensor goes bad and many other problems seems the same, like: bad TB, O2 sensor, injectors, vacoom leaks in hoses etc....
In my case these symptoms came when I disconnected the battery -> ECU's memory of TB adjustment and learned values of engine parameters where cleared, the TB adjustment didn't seem to succeed. the idle was wery poor and when driving the acceleration was awful. The solution was bad MAF sensor. The ECU couldnt relearn the values because it didn't get any reasonable values from MAF sensor. So why that happened after ECU was restarted and before that the car was quite driveable... -I think reason was that when the sensor was getting bad little by little the ECU adjusted oneself to these wrong values and it could somehow manage it. When I replaced the MAF sensor the car was almost better than new. Idle was constant and acceleration good and smooth.
So the lesson was that if you hawe any kind of problems with idle and/or the car is jerky but you don't get any trouble codes or check engine light, CHECK THE MAF SENSOR. It's easy to notice. Just take of the MAF sensor and look at it agens light, the surface of the sensor inside the tube have to look like mirror when it's OK. If there is any dots like fly's shit that MAF sensor is gone.

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