I have a 2007 Harley Davidson F150 (non supercharged, AWD) and its always done fine. Well... the other day, i noticed a bucking of the motor but didnt think nothing of it cause it was fine again. Well when pulling my boat out the water, it started this bucking BAD and almost like a knock. Got it out the water and made it home with it only randomly doing it. I changed the oil just because. Its been fine lately but i figured this much out....

I can make it do it now. My driveway has a SLIGHT rake. When i put my truck in reverse to back out, if i let it be in a bind trying to back up hill, it starts this horrible knocking and even killed the motor. I crank it and its fine all over again and can repeat this process. Then I drive it all day and its fine.

Any clues at all? entire truck starts shaking when it happens. It has to be something stupid because the truck drives great and sounds good. I throw it in park and can rev it up and down without a hiccup but something isnt right. any help?

Could a camshaft position sensor cause this?

 

When was the last time the plugs and fuel filter were changed?

 

also could be a coil. how many miles on the truck ?

 

i just had my engine replaced by the Ford dealership
I have a 2008 F150 xlt V8 5.4 triton
The original engine had 44K miles and was perfect until it was hydrolocked.

This new engine barely makes a noise unless i hit 4K rpm (very smooth)

However I hear the same knocking noises and the shaking of the vehicle.
No idea wtf is going on.
it happens when I slow down or stop randomly (traffic lights, parking lot)
When I rev it, the noise and wobble goes away. when I turn it off and turn it back on it goes away.

 

I had same EXACT issue with mine recently. 2004 FX4 S-crew 145k miles. It would shake violently when put into reverse. Rarely when coming to a stop. I changed plugs and boots and have not had the shake since. I thought the engine was on it's last leg but all seems good now.