Hey guys,

I have an 08 F150 Supercrew KR with 100k miles on it. I bought it used at 95k miles and have noticed what I can best describe as a shudder. I have narrowed it down to it only happening when im accelerating out of overdrive (going up a hill or slight incline). It will just be clunk or two and sometimes its worse than others. I have read a ton and can't really pin point the problem. I had the transmission fluid changed last month as well. I have learned how to drive it so it doesnt happen, but would still like it to be fixed.

Thanks

 

Low grade misfire, at 100k a spark plug change is overdue. That's exactly where in the powerband a misfire is most likely to occur.

 

I agree. You described the classic misfire to a T.

 

So that should fix my problem? Just replace the spark plug?

 

About a 99.5% possibility. That type of misfire is almost always sparkplugs.

 

Is that something I should probably bring to a mechanic to do? I've heard it can be tricky.

 

You have an 08, if it is an early 08 with the black spark plug boots, it can be tricky. I would advise a Ford dealer or at least someone that has experience removing the two piece plugs. If it is a later 2008, with the brown sparkplug boots, it's a normal plug change that any good mechanic can do.

 

Here is an easier way to tell which plugs you have as posted by MGDfan:

https://www.f150online.com/forums/5076063-post29.html

 

Probably a misfire...had same problem a few years ago...swore it was the transmission because it wouldn't do it when the OD was turned off.

Turned out to be a bad coil on #3 cylinder...FWIW...

Dealer tried changing the transmission fluid, TSB on the valve body, replaced OD snap ring...but it didn't fix it...

 

That was my next question.. until i get it fixed should I just turn overdrive off? Whats the disadvantage with doing that?

Yall have been a great help I really appreciate it.

 

Same issue i had last year (shudder on uphill or slight incline). I changed all the sparkplugs and now truck runs like a champ. Make sure you have the lisle sparkkplug removal tool when you do the job yourself. Out of 8 sparkplugs i broke 1 and the tool getthe job done yanking the broken piece out.