Nissan Repair: 2000 maxima knock/ping, mass airflow meter, oxygen sensors

Question
My 2000 maxima SE has had this ongoing issue with engine knock/ping and associated poor performance especially bad around 3000-3500 rpm. When I took it to the dealer they attributed it to the mass airflow meter. They replaced it and the car seemed to run strong for about a hundred miles or so and then went back to knocking again.
After awhile I decided I would take it to a local car mechanic and he said the same thing that it was the mass airflow meter. He replaced it then took it to the dealer for a computer flash upgrade and it ran strong for a little while. He said the flash upgrade made a big difference.The knocking seems to be inconsistent some days it knocks worse than others. I think when they replaced the meter it was the computer reset/upgrade not the new meter that made it run better. I have reset the computer myself by disconnecting the battery and feel the condition improves after doing this. I have also felt that filling the gas tank helps the problem. I even think sometimes just pulling over to the side of the road removing and reinstalling the gas cap makes a difference. I always use premium gas from Exxon or Sunoco. My mechanic does not think the problem is with the knock sensor for some reason I think he said the knock sensor is basically for lower rpm or something like that. The Maxima has a permanent fuel filter located in the tank and I wonder if it could be clogged as the car seems to run better with a full tank. Would having my mechanic check the fuel pressure tell me if the pump is bad or the filter clogged? This knocking and power loss seems to be a common complaint about these cars but no one has a good answer. Thanks in advance for any usefully input - Corey

Answer
Corey,

I personally have a 2000 Maxima SE.  The problems I have had have been the oxygen sensors, (all three) and the coils, (all six).  If your power drops off and the engine pings it is either the knock sensor or the car is being starved for gas.  If you are running good gas, which you are, the fuel pressure needs to be monitored, Get an adapter kit and hook up a fuel pressure gauge.  Drive the car with the gauge taped to your windshield.  You will drape the hose under the hood and use duct tape to hold the gauge, low on the windshield.  Shutting the hood should not cause a problem as there is a rubber gasket.  Now, drive the car and when it knocks and power drops note what the gauge is doing.  My guess is the fuel pressure will be constant.  If not then the pump or the relay is defective.  If you have good fuel pressure have the mechanic check and possible replace the knock sensor.  My bet is the sensor is bad.  Also, you did not mention if there were any codes?  I would think the car would throw a code.  Mine did for both the oxygen sensors and the coils...