I did a fresh tune up on my '97 F150 4.6 at the 105k mile mark including all new plugs, wires, fuel filter, PCV, etc. I even cleaned out the EGR and MAF, etc. Exactly one year later at the 130k mark, I started feeling a major miss and got a misfire code. I pulled all the plugs and most of them were toast, obviously from detonation since all the tips were white. I decided to switch to 2-step colder plugs to attempt to help the detonation, but no dice. It ran perfect for only 5k miles and now the miss is back again. I need to do a third plug change in 30k miles.

From my first spark plug change, I've been running 93 octane and it still pings at highway speeds.

What am I missing??

 

White plugs indicate a lean condition. You may also have a head gasket leak that is letting engine coolant into the cylinders. How is the coolant level?

JMC

 

The coolant level seems to be fine. I've never really had to add any coolant since I bought it 30k miles ago.

I've done everything in my power to correct a lean problem, without getting into the computer, etc. I've done a ton of searches and have checked or fixed everything I can find. I guess the last resort is to pull the octane bar or get some kind of retune.

 

Just out of curiosity, what kind of plugs did you use?

 

I just thought of this. Clean the Mass Air Flow sensor. If it is dirty it can cause a lean condition.

JMC