Good morning. I think I'm in the new members area. if this is the wrong place for thies, my apologies. I have a 2004 Toyota tundra base model with the 3.4L 6-cylinder engine. My brother bought it new and didn't use it much. He gave it to me for my birthday a couple of years ago. Love my truck. It has dings and scratches but mechanically it is in good condition with 157k miles on it. I need some advice and would appreciate you pointing me to where someone may have already started a conversation. The engine has this thing where it will burn the spark plug on cylinder 4. My brother and now I have to replace it at least twice a year. The spark plug does not look damaged, just burnt. I replace it and the truck is back to normal. Yesterday, I cleaned out the MAF senser, the Throttle intake. I replaced the gas cap. Replaced a couple of vacuum hoses, the spark plug wires. I did all this because I recently replaced all the plugs. I put in the Denso double platinum plugs. It felt more like a vacuum leak. But since the code it was throwing was a misfire on Cylinder 4, I replaced the plug, and the problem went away. I don't believe it's a head valve, but maybe. Anyway, any advice would be much appreciated.

 

when you say burn the sparkplug, what does it actually look like? It it black and sooty, or the electrode missing, or something else?
I'd do a compression check first since that's quick and easy, but it could be that fuel injector is sticking open causing a very rich condition in that cylinder, or sticking closed causing a lean condition and higher combustion temps...
If you have a scan tool with live data, check the long term and short term fuel trims at idle and at 2500 rpms.
You can also swap the coils around to see if somehow that coil is causing an issue, but since each coil runs two cylinders that seems unlikely.

 

how did you work out that issue ?