[mrmole]

I bought my 07 Expedition new. Serviced at recommended intervals by selling dealer. For over a year the engine has hesitated (misfired?) intermittently. Only happens when engine is completely warmed up and almost always under load either accelerating or going up a grade. Dealer has found nothing on diagnostic scan and stress tested coils which are ok. The problem is happening more often. I am open to ideas what is going on.

 

[oldtimer35]

I think you might have a problem with the coil firing throught the boot. Without scanning it you would have to pull each one and look at the boot. Your looking for a small white hotspot on the boot where the coil fired thru it. Sometimes these are hard to see, even to the experienced eye. You might have to pull the plugs to see if they have traces of carbon from the misfire, but lets hope not, since are a bear to remove. Not to be tried by the inexperienced!!!!!!!!!:mad2: Hope this helps

 

[Poppy]

Funny I was speaking with a friend about this earlier today, I suggested that it might be a faulty, or dirty MAF sensor. DOn't know if I was right, but it is a thought.