I have a 2007 F150 Supercrew with the 5.4L engine and 39k on the clock.

It has a slight vibration that's worst at 1800-2000 RPM. The vibration is most evident when spun unloaded and out of gear, holding RPM with the throttle. It also has an odd note to the exhaust, an slight drop-out in the sound that corresponds with the vibration. To my old-school senses it feels like a weak cylinder. It has set no codes.

I took the truck to a local dealer. The service writer set in the truck with me and I showed him the problem. He agreed there was a vibration. The mechanic hooked up the code reader and said there were no codes (duh, I already told him that) and proceeded to tell me in a condescending way that a vibration at that RPM was normal and that the funny note to the exhaust was a result of the Magnaflow and duals that have replaced the stock exhaust system.

I've been wrenching on engines since before the mechanic or the service writer were in diapers. I've built motors of every stripe, size, and nationality. I still contend that there is something amiss. Unfortunately there are no fault codes and, not being familiar with the 5.4L, I don't have the first-hand experience necessary to dispute the mechanic's contention (I bought the truck lightly used a few weeks ago). I do have experience with the 4.6 mod motor (Crown Vic Sport with extensive mods) and it never felt anything like this.

So, who's right? Is the vibration something truly endimic to the 5.4L or am I being given the brush-off?

Brad

 

You might start my running a compression test. It should be pretty smooth at 1800rpm.

 

Had a load balance test run. Nothing. If I understand the test properly, it should identify a cylinder that's weak for any number of reasons including spark, fuel, and compression.

Another tidbit. If I put the truck in gear and run up the RPM against the brakes, you can't feel it. That, plus the passed-with-flying-colors load balance test, leads me to believe it's some kind of imbalance that hits a harmonic at around 1800.

My first impluse is to pull the inspection cover on the tranny and see if there's something amiss with the torque converter or flywheel. But I'll take suggestions at this point.

Brad

 

i don't know if it'll help, but my uncle's Navi has the same engine & i found a significant amount of water in one of the spark plug holes. I blew it out with an air hose, let it all dry, & the truck purred like a kitten after that.

 

Already been through every coil, including inspection of the plug holes. Nada.

Brad

 

Hey Brad I have a 2005 XLT wit the 5.4 it has 27,000 on it. And it does the same thing. The engine has always had a slight twitch when idling if you run the rpm up it has a vibration at around 1800 put it in gear and run it up against the brakes nothing. I have had it to a few dealors. All say its normal. Everyone else is complaining about piston slap, cam phasers making noise, and breaking sparkplugs off. mine runs quiet as a mouse I guess I can live with it. When I was younger and had a nissan truck, The engine had the same caracteristics,I took it several dealers and was told that when all the engines are test run at the factory, that the smoothest running engines were put in the cars and the engines that were not as smooth were put in the trucks. Maybe Ford does somthing similar, or maybe they blew smoke up our you know whats.