Hot? start up ping

I have a 2000 Nissan Frontier V-6 (California) which when it is started in the morning, pings on light to moderate acceleration. After about 2 minutes the ping disappears.

It will not repeat this when it is restarted after parking if started again within a couple of minutes. If parked longer than about 7 to 10 minutes, it will again ping for as much as the first 2 minutes of driving, even with very light acceleration.

I had this car recently tuned, with this specific complaint. It didn’t change one bit. (I’ve been referred to Nissan as a cop out.)

Is there a possible connection with the oxygen sensors? I am thinking that the engine can not cool off that fast to influence the ping, but the exhaust system might cool enough to make a difference. If so, would it most likely the pre-catalytic sensor(s)?

How could I diagnos this? My OBD reader does not show any faults. Unplug the sensors?

Thanks, Wilbur

It could be that the EGR system is being disabled for longer than it should be. None of the possible causes you listed are very probable; a miracle would be more likely. In the olde dayse the EGR would be disabled for about 30 seconds after startup. The source of the EGR problem would be hard for me to point out because I am not too into the present day technology.

have you tried running a tank (or two )of super through it to see if the increase of octane helps?

I don’t think it’s pinging. I think it’s something loose when the engine is cold. Maybe in the valve train or rod bearings. When the engine gets hot it tightens up.