Hello everyone,

My truck started bucking a few months ago between 40-55 mph. Under light acceleration. If I start bucking and hit the gas hard, it stops. If I keep constant light acceleration it will keep bucking until I get a bit higher in speed. If I let off the gas it stops.

I added the foam around the air filter. Did not stop the bucking. No codes are shown.

2006 F150 Super Crew XLT
Truck has 136k miles.
Engine is 5.4
Spark plugs changed at 80k miles at dealer.
I have to check when the fuel filter was replaced, if it was.

Any checks I should do to narrow it down?

 

Does the engine light flash at all?

 

No it does not.

 

I had this start to happen on my 2007 and it turned out that the intake manifold had warped because its plastic on top of an aluminum engine body and then it caused my spark plugs to burn up. It had around 116K on it and had the spark plugs originally changed around 80k.

 

What does that repair look like? Hard, pretty basic once I get the parts? Have not done a lot of auto work. Pretty handy though.

 

Whenever I hear "bucking" I think of coils but it could be fuel filter, fuel pressure driver module or dirty fuel injectors and so on. I would at least do the filter, its so cheap. Did you change the air filter while you were doing the foam and also try cleaning the throttle body, not too bad of a job

 

Yes, check the fuel pressure driver module (FPDM) above the spare tire. The module can corrode or crack. I totally forgot about this one.

 

I would bet coils myself. But it never hurts to replace a fuel filter.

 

Update:

Last night:
-I cleaned the IAC Valve
-Cleaned the air mass flow sensor
-Replaced the air filter

This morning still bucked. But I finally got a fault code. P0305 Cylinder Number 5 Misfire Conditions.

What would you do next? Still replace the fuel filter or go straight to coil?

 

Swap coil 5 with another one, clear the code, and see if the problem moves to the new cylinder.