Ok I thought I had the infamous bad spark plug vibration. So I had the replaced yesterday they all came out without breaking. I drove it around and it still has a vibration between 40-50 when it downshifts. Now if your hard on the throttle it doesn't do it but if your kinda lugging it along that's when it happens. I thought for sure from the reading on here the spark plugs would of taken care of this.

 

Now it's time to look at the coils. How many miles on it?

 

89000

 

i just had my plugs done had the same issue and now its gone only difference is all but one broke and i had like 95,000 on those plugs and the original fuel filter has 167k on it so after a few days it seems better than ever

 

I thought of the fuel filter. Even though there isn't a check engine light will a misfire read on a scanner.

 

apparently mine did my buddy turned it upside down and nothing but black nasty sh1$ came out of it. plus he said i had a bunch of lean codes on the computer that didn't trip any lights, but he is a ford mechanic and does it on the side and had his work computer lookin it all over

 

Why? That's just poor maintenance. Change every 30k.

 

well i honestly do the best i can but there are things that get forgotten until something else comes up. I do the oil every 3-4 k but when things get busy on the farm you tend to loose track of miles since the fuel filter was changed

 

Coils will make for a vibration at certain speeds?

 

I took it back to the garage and by then you could barley hear or feel the vibration. The mechanic added a friction modifier to the transmission and now the truck I can't hear feel nothing. So that's where I'm at now.

 

Yes - under light throttle in overdrive around 45 mph or so. It's called a low grade misfire.

 

Interesting...