In my GU 2004 ZD30TDI Patrol an Air Flow Mass Meters (genuine Nissan's)fail in less then two years (aftermarket ones in 7 days-LOL). It started soon after a failed alternator was replaced in 2009. I have just replaced 4th AFM meter. Dirt, oil etc has been ruled out, they fail electronically. Does any one is having similar experience?
Apart from suspicion of poor quality of Nissan's AFM meter I also suspected the new alternator. It produces for most of the time 14.8V no load (have temp/volt meter mounted on dash) but I have noticed that it spikes while driving to 15V or little over. Is that normal voltage?

What should be a correct voltage from original Nissan alternator?