I replaced the NGK G-Power plugs that I have been running in my car (2005 Subaru Impreza RS) for ~33k kilometers (~4.5 years) and was surprised to see the centre electrodes on two of the four plugs worn as shown in the following photo:
Because of the DIS ignition and the fact that G-Power plugs have platinum on only one side, I was anticipating asymmetric plug wear. (G-Power plugs are economical enough that I figured I would just change them out at copper intervals.) However, I assumed that most of the wear would have been on the ground strap - not the centre electrode since it has the platinum puck. As such, I was rather surprised to see the centre electrode worn as shown. For comparison, here is the plug from the DIS "pair" cylinder:
It looks perfectly normal with a some wear on the ground strap.
I sent the photos to NGK and they suggested that it could possibly be due to an overly aggressive ignition. I suppose it's possible but the ignition on the car is stock from the factory. No mods have been done to the car.
Does anyone have any theories as to what could cause the centre electrodes on a plug to exhibit accelerated wear? Or, is my assumption that the DIS ignition would wear the conventional ground strap more that the platinum centre electrode incorrect? Is this normal wear for 33k kilometers (20.5K miles)?
Thanks,
David
Because of the DIS ignition and the fact that G-Power plugs have platinum on only one side, I was anticipating asymmetric plug wear. (G-Power plugs are economical enough that I figured I would just change them out at copper intervals.) However, I assumed that most of the wear would have been on the ground strap - not the centre electrode since it has the platinum puck. As such, I was rather surprised to see the centre electrode worn as shown. For comparison, here is the plug from the DIS "pair" cylinder:
It looks perfectly normal with a some wear on the ground strap.
I sent the photos to NGK and they suggested that it could possibly be due to an overly aggressive ignition. I suppose it's possible but the ignition on the car is stock from the factory. No mods have been done to the car.
Does anyone have any theories as to what could cause the centre electrodes on a plug to exhibit accelerated wear? Or, is my assumption that the DIS ignition would wear the conventional ground strap more that the platinum centre electrode incorrect? Is this normal wear for 33k kilometers (20.5K miles)?
Thanks,
David