2010 XLT 4X4 w/5.4 & 2800 miles has had a "shudder" at 40-50 mph's under moderate and mod-hard acceleration.

Seems to happen right before 4-5 gear shift. Has happened at times during downshift also. Acceleration does suffer so torque is affected.

Feels like a misfire or riding over bumps.

Doesnt matter if engine or tranny are cold or up to temp, also happens in tow/haul mode in fact it really became apparent and worse than ever when I towed the boat this weekend...when merging into traffic shuddering kept me from getting up to speed, had to floor it and downshift.

My F150 was built 10/09 and seemed to have the harsh 1-2 upshift and bump at low speed that some folks had with the early 2010's but that has gotten alot better and appears resolved however this shudder has gotten worse.

Was wondering if harsh upshift TSB will resolve this problem or if this is an entirely different animal.

By the way, as a new member/first time poster and previous owner of a 99 f-150 this forum is invaluable to us owners and more informative than some of our service advisors.

 

Sounds like a coil on plug failure... intermittent. Sometimes they only fail when under load, like when the trans is locked up and wants to shift/downshift but hasn't yet. Again, could be the trans too... Get er checked out.