6.9 misfire at higher rpm

[6.9idi_sam]

If I remember right my grandpa told me that the injectors were replaced right after the warranty expired. Trucks an 85 so that was probaly around 88-89. I don't think it's my valve train. You could hear a valve tick at least. I feel like a injector is bad or my timing is "advanced" from the added fuel pressure

 

[icanfixall]

What has been posted by agnem above is about as correct as it gets. Mel owns Conestoga Diesel in Pa and makes several different injection pumps from mild to wild for our engines and many other brands. I'm reading that the pump and injectors are 20 years ols but low miles on them & installed by Ford. Do you recall if the injectors were new or rebuilt? The years or miles on them have no bearing on what you describe is happening but. If the injection pump or injectors were of low quality (which is what I suspect) then there is your problem. Have the injectors tested or just replace them now with NEW or rebuilds from a known good rebuilder. If recommendations are needed for a good injector source please ask before you go and purchase the cheapest on ebay.

 

[6.9idi_sam]

Not sure what brand I'm assuming oem remans. There is some diesel on the outside of one by the glow plug. I was thinking accurate diesel remans