I've been noticing a vibration throughout rpm range but especially at 1400 to 1700 rpms. Anyone out there ever experience anything like this? The truck seems to run fine and has a lot of power but the vibration is very annoying.

Sean

 

Anyone have any ideas? Mostly noticable in park @ 1400-1700 and is felt mostly in steering wheel but is felt throughout the truck as well. Also felt under acceleration like a mis. Problem started about 3,000 miles ago.

2000 F150, 5.4
83,500 miles on truck
New plugs Motorcraft AGSF22WM (changed 4-8-05)
New Motorcraft DG-508 cop's (changed 4-8-05)
New fuel filter (changed about 3,000 miles ago)
Rebuilt autotrans (1,000 miles on rebuild) - (Problem there before and after rebuild)
MobilOne Synthetic changed every 3,000 miles
MAF cleaned at trans rebuild
PCV checked and has plenty of suction
Vacuum Check - Haynes manual 22" and responds as "Healthy"
Air Cleaner - K&N cleaned and oiled as needed


Sean

 

Cel lite? Codes set?
Could very well be plugs or related ignition.
The increase in the 14 to 1700 range may be when the EGR system is called into operation.
The fuel mix goes lean and the plugs cannot fire reliably at that time.

 

Get the codes read. Even though you dont have a CEL you still might have a stored code. Most autopart stores will read them for free.

 

Hey Guys,

Just read your posts and went out and scanned for codes (have a scanner) "PASS - No Codes Returned" it says. No CEL either. I've been after this for the last 3,000 miles or so. Hopefully it isn't serious.
It started out as an occasional small vibration and steadily grew into what it is today. I tried out Seafoam today and it's still there but the other 8oz's is in the tank so we'll see. In other threads, it looks like I should maybe check out the EGR valve. I had the EGR tube off of it a couple of weeks ago and it was all clear.
Don't know what it could be.

Sean

 

If you put too much oil on it the mass air get fowled and can cause problems. Did you clean your IAC?

 

No not yet. The EGR & IAC are next on the list although I've read various other posts and thought that cleaning the IAC was for erratic idle or surging? Please enlighten me.

Sean

 

Well, I ran Seafoam through it yesterday (8oz. & other 8oz. still in the fuel tank time will tell), just got finished cleaning the entire throttle body, IAC, and EGR out with STP throttlebody cleaner. It was amazingly pretty clean inside (no where near some of the discriptions I've read) just a thin black coat throughout.

It's still there. I've read several posts (4 or 5) that talk about this vibration (1600 rpm's) but no one ever replied to put the subject to rest. Anyone know what the #### this vibration is?

Sean

 

after reviewing the following posts...the next stop is a compression test on all cylinders....all in favor?...zap!

 

I was afraid you were going to say that. I've been thinking the same thing but didn't want to pull the coils and plugs again (4th time).

Sean

 

While driving the truck yesterday, I realized that the vibration was gone while sitting at a stoplight. I was extremely excited! took the truck out of drive and put it into nuetral & park and it was back. Put it back into drive again and it felt almost completely gone again. Light turned green and I stepped on the gas and back again.
I believe that the Seafoam is working but now I need new pads heard the wear indicators start to squeel.

Sean

 

Finally got a code! P1400 - DPFE Low Voltage. Got Haynes Manual out and it says back probed it should read between .20 to .70 while cold and 4.0 to 6.0 volts hot (warmed up). Mine reads .97 volts @ cold or hot.
After reading a few posts around here it's been said to have an affect on a lot of things such misfire symptoms and vibrations. Could this be what's been going on with my truck?

Any input would be greatly appreciated, Sean

 

Well, I took it into Ford today and had it hooked up to the WDS Scantool and the results were:

Tech Notes: EEC Test KOEO KOEC KOER All pass power balance. Relative compression and injector flow all test ok. Road tested with WDS and could not find a problem.

I talked to the tech afterwards and he assured me that the motor was mechanically sound, but that he did notice the vibration. When I asked him about what would be the probable cause of the vibration, he commented by saying that it would or could be a long and tidious road trying to figure out where the vibration was coming from.

At least it's mechanically sound. I was worried that maybe it was serious. It just started about 3,000 miles ago could it be a motor mount?

Thanks, Sean

 

That's true. NVH diagnosis is usually involved and time consuming. Sometimes, you gotta make a SWAG at it and see how it turns out.

I might be reaching, but there may be an internal engine or accessory imbalance. Next time it acts up, try taking the serpentine belt off and running the truck to see if it's still there.