ruckus226

Hello all,

I had a new exhaust and headers installed on my f150 5.4l crew cab about a month ago. It has this bad vibration that I cannot hear outside of the truck but I can feel it in the gas pedal and the floor board. It is especially bad if I shift into reverse while holding the brake, and then accelerate a little. Under light acceleration turning left it will do it and turning right i feel nothing. Any idea what this could be? I took the tailpipes off and its just dumping out of the muffler at the moment trying to track this down.

Thank you

RLXXI

With the truck on flat ground, loosen all the exhaust clamps as well as both motor mounts, now fire it up and power brake it in drive and reverse a few times, then while in neutral/park, rev the engine a few times then shut her down, now re tighten everything you loosened.

That's how Ford taught us to eliminate those kind of issues. Sometimes it don't work and they had us add weights to the exhaust to absorb such vibrations.
.

ruckus226

that is the craziest thing I have ever heard, but it might do the trick LOL. It's driving me nuts. It's like I have abs in my gas pedal.

RLXXI

First time they told me about it I thought the same thing but 90% of the time it cured the problem. I do have to add it happened mainly on new(er) vehicles. Something about things getting bound up on the assembly line, yada yada. Also if engine vibration is transferring to your accelerator the chances are good your motor mounts have hardened or separated allowing engine vibration to transfer thru out the vehicle.
.

ruckus226

that I could see.. But I know for a fact it didn't do this before the header/exhaust install. I did have a heat shield rattle on the drivers side down pipe but fixed that by taking it off.

RLXXI

Yeah it sounds like you have an exhaust vibration transference issue.
.

ruckus226

That's what I was thinking, I know the passenger side tailpipe is really close to the shock, thought maybe one of those may have caused the issue. Do you think the angle of the muffler could cause an issue? for instance it kind of ramps down. Possibly changing the angle of the cats to cause a vibration? Just throwing stuff out now, but if it works it works. Idk why I would feel it in the gas pedal though.

RLXXI

Vibration issues are at best a somewhat ghost in the machine when nothing is obvious. Isolate it like I said. There are a lot of frequencies different systems in our vehicles operate on and when you get one on the same frequency as another it can cause all sorts of headaches.
.

ruckus226

I might try that out if i can get to the motor mount bolts. 15 years in michigan isn't going to be fun to try and loosen them.