Hi everyone,

I'm posting this question on behalf of my father who recently purchased a 2006 F150 Lariat Supercrew with the 5.4L.

When cruising anywhere between 35 and 50 mph, if you accelerate heavily, the truck will downshift as it should but as it picks up speed, it bucks and hesitates while doing so. I had the rear window open yesterday and could hear popping noises behind me. I couldn't tell if it was from exhaust or something else. The only way to stop the problem is to let off the throttle and it goes away. Yesterday I kept the pedal down and powered through it and the hesitation and bucking went away after 4k RPM.

Any ideas what this may be? The truck is going back to the place he purchased it from but I was curious if there was anything specific we can look at now or to tell the place to look.

Thank you.

 

How many miles on it?

 

About 81.5k. The Carfax showed it last visited a dealer around 70k.

 

My 06 did the same, I changed the plugs and the hesitation went away.

 

The factory plugs should have been changed at 60k and I bet they weren't. With the sticking and breaking issues I'm betting the original owner traded it in rather than have them changed.

 

I agree with the plugs. The misfires may have hosed the catalytic converters, too.

 

Plugs need to be changed like said....if you're having backfire issues then you have a misfire. Depending on how bad you may have toasted the catalytic converters.

 

Thanks guys. I had suspected maybe the plugs and the catalytic converter with the noises it was making. Hopefully that's not toasted.

I'll mention the plugs to him so he can tell the shop. Hopefully they don't have any breaking issues with those.

The strange thing is that there aren't any issues during normal driving conditions. Even with moderate acceleration it's fine, but it also doesn't downshift during that time. It's whenever it downshifts a gear or two.

 

My 05 was doing the same thing last year. I ended up having to change the plugs and COPs (coils). After that the problem went away.

 

Mine also drove fine until I gave it more than half throttle.

 

My 05 does the same thing. It pops like that and all i was wondering wat i should do to it, Im glad u asked this question,

 

Good to know.

Thanks guys.

 

is the check engine light on? my truck did the same thing. i bought my truck with the check engine light on which the dealer said they would fix. long story short they replaced the o2 sensors,plugs,coils with no solution. then they replaced the cats and that seemed to fix it. untill this weekend when i noticed it was doing it again. this time im taking it to ford.

 

My CEL never came on, my Edge also never caught a code either.

 

hmm.. just got my 05 as well and i can feel a slight bucking on moderate acceleration.. i'll have to go change out the plugs and see what happens!