Not sure where i should have this thread. I just bought a used 06 F-150 S/C FX4 with 120,000 kms on it. When i took it out for a test drive, i ran it hard. A couple of times on the highway when hitting the gas on a long hill, pushing it to about 145-150 kph it would start vibrating like crazy. It vibrated so bad that the engine light would start flashing on and off, and it wouldn't stop vibrating till it got back down to around 60 kph. After the test drive i told them about it, they said they couln't get a read on their sensor because the engine light didn't stay on long enough. After they said it might be a bad sparkplugs, and that they would change them. Sure enough it has happened again, but only once since, and the roads have been snow covered since, so conditions are not great to test it out again. The only thing i know of on this truck that is not stock, is a added rear leaf spring, they were beefed up. Could this affected the drive shaft angle and make it vibrate? Or is this a missfire problem engine problem. There are some smart people on here, i look for any suggestion on locating and fixing this. Thanks Al

 

Not sure where i should have this thread. I just bought a used 06 F-150 S/C FX4 with 120,000 kms on it. When i took it out for a test drive, i ran it hard. A couple of times on the highway when hitting the gas on a long hill, pushing it to about 145-150 kph it would start vibrating like crazy. It vibrated so bad that the engine light would start flashing on and off, and it wouldn't stop vibrating till it got back down to around 60 kph. After the test drive i told them about it, they said they couln't get a read on their sensor because the engine light didn't stay on long enough. After they said it might be a bad sparkplugs, and that they would change them. Sure enough it has happened again, but only once since, and the roads have been snow covered since, so conditions are not great to test it out again. The only thing i know of on this truck that is not stock, is a added rear leaf spring, they were beefed up. Could this affected the drive shaft angle and make it vibrate? Or is this a missfire problem engine problem. There are some smart people on here, i look for any suggestion on locating and fixing this. Thanks Al

 

Not sure where i should have this thread. I just bought a used 06 F-150 S/C FX4 with 120,000 kms on it. When i took it out for a test drive, i ran it hard. A couple of times on the highway when hitting the gas on a long hill, pushing it to about 145-150 kph it would start vibrating like crazy. It vibrated so bad that the engine light would start flashing on and off, and it wouldn't stop vibrating till it got back down to around 60 kph. After the test drive i told them about it, they said they couln't get a read on their sensor because the engine light didn't stay on long enough. After they said it might be a bad sparkplugs, and that they would change them. Sure enough it has happened again, but only once since, and the roads have been snow covered since, so conditions are not great to test it out again. The only thing i know of on this truck that is not stock, is a added rear leaf spring, they were beefed up. Could this affected the drive shaft angle and make it vibrate? Or is this a missfire problem engine problem. There are some smart people on here, i look for any suggestion on locating and fixing this. Thanks Al

 

Do you get an engine light? If they did not install the plugs correctly or you have a bad COP it could be the same issue.

 

Where does the vibration come from, the engine? They lie about the check engine light those codes are stored go to auto zone and have them pull the stored codes and bring the code #'s here and maybe we can help.

 

CEL flashing on and off is almost always a cylinder ('s) misfire.
I have seen with a couple of Jeep and Dodge products, the CEL will flash/blink rapidly on/off warning of a Misfire but CEL does not stay on but my scan tool plugged in will point out that there was a misfire on a cylinder ('s). Funny thing is, in both seperate cases it was cylinder #1 on different engines.
In both case's, there was a severe vibration.
The Jeep needed a new connector plug for the #1 fuel injector. (inline 6)
The Dodge 1500 needed a complete tune-up, way over due. Wish my
B-inlaw would stop waiting until a major problem arrives, then I get the call. Obviously he doesn't believe in prevent-mailt.

 

It is possible that it could be an engine miss or u joint but I doubt it. Here is why. If you have an engine miss under load it is possible for it to vibrate yes but you said it would not stop until you dropped to about 60 kmph. Once you let off the throttle any engine miss should have diminished as the engine went to an idle. Almost the same with your u joint. Once you back off the forces on the ujoint are almost reversed. Your rear axle is essentially driving the truck. My suspisions would lead me to a tire imbalance. Most likely the rear tires. For the cost I would have them balanced. Keep in mind though when they balance the tires they do not spin them that fast so I can not be sure they will find it but they should.

 

I have done this before. Here is what's happeing. You have a bad COP ( coil on plug) but it only fails under a load (your excessive speed). You forgot to mention which "engine" light came on. It was the "wrench". Your COP started to create a "ping" which you didn't hear at that speed, it got worse then it started to miss fire. In return the engine went into protection mode and only fires on four cyclinders, left bank the right and back and forth, creating on hell of a vibration at that speed. It' won't reset until you slow down to less than 60kph ( no overdrive). Some time in the near future one or more COP's will fail. It's unlikely any testing will reveal which one, as they don't load test them, either they work or not.
Hope this helps.

 

Replace all the COPs, and sparkplugs with Motorcraft plugs.

 

How about a bad Radiator Fan System?.
Possibilities include a Fan Clutch problem including bearings. There could be a bad fan with bent or missing blades or any thing that could unbalance the fan at or above a given R/m.
If there is no CEL observed the cause may be mechanical in nature.

 

I also remember my old 86 Bronco having a similar problem.
Some 4x4 Trucks have a "Dual-Cardan" Joint in the rear drive shaft. Under an extreme wear condition the joint becomes weak and vibrates wildly above some given speed, and may become worst at a particular speed or R/M. The Dual-Cardan (two universal joints enclosed) is mounted in a "fat knuckle" closest to the transmission's output shaft;mid-way under the truck. To check for a cardan problem you can elevate the trucks rear wheels securely on jack stands; which should allow rotating the rear wheels, differential, and drive shaft. The trans gearing should be in "Neutral", and the brake off. Rotate the drive shaft and check for binding, clicking noise, or motion within the cardan joint. If there is any motion within that unit it must be replaced a.s.a.p The U-joints inside may have gone dry and or the pinion coupling may have broken internally to the joint. Either way a replacement should be done a.s.a.p since it could snap the joint in half leaving you helpless.
There is also a "Plunge" Coupling in most 4x4 shafts that allow the shaft to stretch while going over obstructions. The plunge coupling is usually covered by a rubber sleeve. It is usually at one end of the drive shaft;usually down near the Differential.
There is a possibility that the coupling had deteriorated
due to moisture, dirt entering the sleeve and contaminating the lubricant. This situation causes many un-diagnosed shaft problems. If there is any binding or motion within that coupling it will cause exactly what you are complaining about. These conditions are very dangerous and should be re mediated as soon as possible

Peace & Good Luck!.

 

Why waste money needlessly. Replace the **** on the stove, not the whole stove.

(PS the 2004 to 2008 F150 don't have the Cardan or CV u-joint in the any of the drive shafts. Unless you put one there, see my sig)

 

My head is now spinning with all this new information. This vibration mostly happens on long highway smooth hills, accelerating from 80 kmh and holding down the gas pedal till it would hit 145 kmh. I wanted to see if the engine would fail under extreme passing/load. Not that i do this at all the time, but i just wanted to put it to the test. Sorry that i didn't tell everyone that it was in fact my engine light, and not the wrench light that was flashing. The vibrating first starts from underneath kinda and it won't go away until i reduce my speed to 60 or 70 kmh. The coils might be it too, but they said they would know which one if any is failing. I had a little Chevy S10 long time ago, it kinda did the same thing, a mechanic said it was my emergency brake cable sticking. I said WTF! my emergency brake cable? And dammit, he fixed it by replacing the cable. But i don't think its that this time. Parts are so over priced up here in Canada, you guys don't know how luck you are buying parts down there, we get in the *** + 14% taxes!

 

The way this seems to generate it probably isn't the emergency brake but that has definitely been an issue on some of the '04-up new body F-150's. If the EB is not fully released or is sticking a little, some have reported vibrations so bad they had to pull the truck over because they couldn't control it. They also seem to rust in the cam mechanism in the EB in the rear drum. Good luck in finding what the problem is.

 

if you know nebody that works for a ford dealership have them pull it up using IDS and they can run tests to pin point which cyl. may be mis firing, as for the vibration, check the u bolts to make sure their torqued to spec, and depending on high the rear end is lifted it could change the pion angle by maybe a degree but really not enough to have a vibration thats that noticebale, but like i said take it to ford to have them pull it up on ids and have them run tests to make sure where exactly its coming from