Any members have an 06-08 Ford F150/Expedition with the 5.4L engine?

[Brad Johnson]

If you have an 06-08 Ford F150 or Expedition with the 5.4L engine, I need your help.  My 07 SuperCrew has an engine vibration at about 1800 RPM.  It does it worse if I leave the truck in Park or Neutral and run up the rpm.  The vibration feels like a weak, but not dead, cylinder.  There is also an accompanying odd note to the exhaust, also indicative of a weak, but not dead, cylinder.

I've been told by two dealers that "it's normal", but as an old gearhead I honestly feel like it's not.  I had a mod motor (the 4.6) in my now-dead Vic and it was smooth as glass.  Unfortunately I don't have any experience with the 5.4 so I don't have the information needed to refute the dealer's claims of normality.

Thus the appeal.  If you have the aforementioned vehicles with the 5.4L engine, could you do me a favor?  Sometime when it's up to operating temp, put it in Neutral or Park, run up the RPM to around 1800, and hold it there for a few seconds.  Is it still smooth or do you have a noticeable vibration (mine is similar to what you'd feel if someone in the car was doing the knee-jump leg fidget thing).

Also, anyone know how I might go about measuring the vibration frequency?  If it's at 30 Hz then it's a rotational mass issue (30 Hz is 1800 cycles per minute, matching the RPM).  If it's at 15 Hz it's a firing cycle issue (four stroke engine, firing cycle every two revolutions, or 900 cycles per minute).  That will at least help me diagnose the damn thing.

Thanks in advance!
Brad

[Nick1911]

Ford has an interesting thing in their computer code.

So, these engines all have crank position sensors.  This is how EFI is timed.  Someone clever decided that based on when the engine should fire, the crank speed should increase just slightly.  Based on that metric, it could be computed if an individual cylinder was misfiring, and at what rate.

This data is available to a code reader, if you have a good enough one that can get to the Mode $06 data.  It will list a % misfire rate for each cylinder.

This is where I would start.  Presuming you have a coil-on-plug setup, you may well have a coil getting flaky.  Happened to one of the guys I work with who has a 5.4L.

Good luck!

[Jamisjockey]

'07 F150 4x4 XLT CRW with the same engine.  Have never had that symptom before.

[TMM]

wouldn't a cylinder misfire make the check engine light go on? i had a bad plug, it made my truck vibrate sort of similar to your description. vibration depended on engine load and RPM.

rather than measuring the vibration, i'd say a spark plug check would be quicker and easier.

oh, and whatever the problem is, i'm 100% sure that the dealers you talked to are full of BS.

tmm

[Nick1911]

wouldn't a cylinder misfire make the check engine light go on? i had a bad plug, it made my truck vibrate sort of similar to your description. vibration depended on engine load and RPM.

rather than measuring the vibration, i'd say a spark plug check would be quicker and easier.

oh, and whatever the problem is, i'm 100% sure that the dealers you talked to are full of BS.

tmm

At least with ford, there's a threshold that a cylinder % misfire has to pass before it will throw a CEL.  If I recall correctly, it's fairly high for the 4.6L.

[Tallpine]

The truck is probably trembling because it's afraid that you're going to overload it like the last guy did 


Seriously, bad or loose plug wire

[Sergeant Bob]

The truck is probably trembling because it's afraid that you're going to overload it like the last guy did 


Seriously, bad or loose plug wire

What he said...
The plug wire thing.

[Brad Johnson]

No plug wires.  Coil on plug.

I've considered that.  I've seen coils getting flaky on COPS engines that weren't bad enough to set a code.  I was actually going to try diagnosing that very thing this weekend by getting a coil and swapping it out on each cylinder, one by one, to see if the problem went away.

If it does I'm going to have some words with the local dealerships, including a refund on the "Diagnostic Fee" one of them charged me to tell me nothing was wrong (all they did was hook up the computer and look for misfire codes).

Brad

[Brad Johnson]

Found a guy in the office that has an 08.  Smooth as glass.  Looks like a fun-filled weekend of diagnostics.

Brad

[alex_trebek]

This might be dumb, but would a tuning fork work to detect frequency of vibration?

If so, and you know someone who is a HS physics teacher or a huge dork, you might be able to use forks to determine frequency.

The only other method I can think of is a glass of water and a strobe light. Idk if you could find a sensitive enough strobe light though.  Uses the light and watch the liquid surface. If the surface appears still then you found a multiple of the frequency. Be sure it is dark when you do this.

Anything else would probably require expensive equipment to measure the vibration.

[Gewehr98]

Isn't there this little nagging voice in your head telling you that this truck is going to bite you in the posterior eventually, Brad?  

[Brad Johnson]

Yes, there is.  I've already talked to the dealer I bought it from and they said they would trade it out.  I'm seriously considering taking them up on it.

Brad

[Northwoods]

Yes, there is.  I've already talked to the dealer I bought it from and they said they would trade it out.  I'm seriously considering taking them up on it.

Brad

After the 'spension issues, and now this I'd have the dealer take it back.  The previous owner obviously abused that truck.  Whether that's related to the engine issue or not is hard to say with certainty, but I wouldn't want to bet an expensive engine/transmission on that.

[roo_ster]

Isn't there this little nagging voice in your head telling you that this truck is going to bite you in the posterior eventually, Brad?  

I wasn't going to say anything further...

[CNYCacher]

This might be dumb, but would a tuning fork work to detect frequency of vibration?

If so, and you know someone who is a HS physics teacher or a huge dork, you might be able to use forks to determine frequency.

The only other method I can think of is a glass of water and a strobe light. Idk if you could find a sensitive enough strobe light though.  Uses the light and watch the liquid surface. If the surface appears still then you found a multiple of the frequency. Be sure it is dark when you do this.

Anything else would probably require expensive equipment to measure the vibration.

Timing light

[Brad Johnson]

Spent the last two days going over everything with a fine-toothed comb (electronics, mechanicals, body, interior, etc.) including a trip the dealer for a load balance test and some pretty extensive research on the web about potential 5.4 vibration issues.  The load balance test came back almost absurdly normal, no drop-outs or other issues and all cylinders within a few percent.  Darn near a textbook example of what a perfect test result should be. 

Aside from the original suspension issue (corrected by the dealer I bought it from) and the paint, everything is in excellent shape.  The engine and tranny are mechanically fine and have no leaks.  The electronics are factory and show no signs of rips, tears, burns, overloads, abuse, or potential problem points.  The body is straight and all the parts fit and function properly.  The frame measures perfectly straight.

The vibration thing, well... From what I can find on the web some 5.4s "just vibrate a little", and it's usually at that 1800-2000 RPM point where I can feel it.  In very, very few instances has it eventually manifested itself to be anything other than a minor annoyance.  In those cases there was usually accompanying symtoms of an underlying problem, none of which I seem to have.  I am extremely sensitive to mechanical quirks in a vehicle so I'm about ready to chalk it all up to being hyper-critical.

As for the paint, I did get an excellent price on the truck based on what KBB and Edmunds say it should have sold for.  Enough to comfortably offset the top/hood repaint and have beer money left over.

All that to say I've made up my mind to keep it.  I love the way the truck looks, rides, drives, and performs.  Aside from being a little (actually a LOT) thirsty, I'm thoroughly satisfied with being a truck owner again.  From all appearances, and from what my fairly extensive bumper-to-bumper evaluation has determined, the truck will probably be as reliable as any of it's age and mileage.  The only remaining hicky is the paint, the cost of which was offset by the savings in purchase price.  That considered, it would be silly to trade into another unknown just to salve my personal animosity towards a vehicle that I like and that is, by all objective criteria, fine.

Brad

[RocketMan]

I wonder if one of our TX members will be getting this call from Brad:  "Help!  I'm broke down 50 miles east of Bumfarkle.  There ain't nuthin' out here, and I need a ride." 

Seriously, were it me, I'd be tempted to keep the truck if for no other reason than to find out if there really is a problem.  Curiousity and cats, and all that.  Plus, from your description it does sound like a sweet vehicle.  Best of luck with it, Brad.

[Brad Johnson]

Seriously, were it me, I'd be tempted to keep the truck if for no other reason than to find out if there really is a problem.  Curiousity and cats, and all that.  Plus, from your description it does sound like a sweet vehicle.  Best of luck with it, Brad.

In all honesty that's probably part of the reason I decided to keep it.  Plus, it still has 10k on the powertrain warranty so if something goes Kaboom it's covered, including the tow.

Brad

[Tallpine]

In all honesty that's probably part of the reason I decided to keep it.  Plus, it still has 10k on the powertrain warranty so if something goes Kaboom it's covered, including the tow.

Brad

Well, there you go!

You oughta put a load of bricks in it and see if you can break it 

[cassandra and sara's daddy]

i need to haul gravel for my driveway  i'll cook a great dinner when we are done  only 5 miles to the gravel source

[Parker Dean]

I'd be interested to know what the emissions looked like in RPM ranges above, below, and at the affected range. You'd need at least a four-gas analyzer which you would probably only find at an independent shop that specializes in driveability. If the emissions at the affected range are normal in relation to the above and below readings, then you've got something else going on like motor mounts or a torque converter. If the emissions shoot up, and it'll be obvious, then you'll know it's something with the engine like an EGR valve, EGR solenoid, injector, mass air meter, program revision, etc.