I was reading in the thread about carburator problems where someone had a 
problem with an air flow sensor and ended up converting to a carburator 
because of the high cost of a replacement air flow sensor.  After rebuilding a 
2 liter type 4 from a 78 Westfalia, I also had a problem with the engine 
cutting out at normal operating speeds and traced it back to the air flow 
sensor.  I did'nt even bother checking on the price as I know it would be sky 
high.  The Bently book said that the sensor ir not adjustable or repairable.  
This is not exactly true.  What goes wrong usually when this problem occurs is 
 the voltage feedback resistor, which is a deposit on the circuit board, wears 
through where the wiper contacts it.  This will create dead spots and will 
cause a 0 volt feedback.  I was able to repair this condition by loosening the 
wiper clinch bolt and sliding the wiper off of the shaft.  It will only go 
back on one way so don't worry about marking the position. Next I removed the 
4 screws that hold the connector to the side of the housing and then pull the 
connector loose.  Now the circuit board is completely exposed.  remove the 4 
screws holding in the circuit board and then the circuit board.  Using a small 
rat tail file enlongate the 4 screw holes in the circuit board so that the 
board will be able to be mounted about 1/16" closer to the wiper shaft.  Now 
reassemble everthing in the reverse order.  
If done properly this will let the wiper contact a different area of the 
resistive deposit on the circuit board and everything will be nice and smooth 
again.  I hope that this will save someone from having to spend lots of money 
to replace the air flow sensor.

Rod Trunnell
78 Westfalia