I have a harmonic vibration issue, from 1500 to 1800 or so RPM. Usually is very noticable going slow, about 40 or so. Does not seem to matter which gear (automatic) i am in, as long as there is no to slight load on, it will vibrate. The steering wheel seems to carry the most vibration, just a harmonic, in and out vibration. So far I can tell you it is NOT the water pump, alternator, ac compressor, fan clutch, any drive shaft and ujoints.

My neighbor is a ford mechanic and has a new solus scanner and we tried to do some testing and all we could get was an injector buzz test, the scanner will not even start a contribution test, just errors out. I tried unhooking the batteries, removing the DP tuner, etc. Just plain stock, it still wont do any thing. The most I have seen was when you throttle the engine while trying the contrib test, it will error cyl 8. Otherwise, THERE IS NOTHING.

The only other info I feel may contribute is there is a slight miss in the idle, cant really call it a miss, but its not perfect smooth. The other weird factor is my remote start. It is connected to the WTS and tach. The truck will start, run about a minute or so and shut off. Then start up again, run a few minutes and shut off. The colder it is, the more the frequency. If its 30 or below, it will do this 3 or 4 times within 10 minutes. If its about 40 or so, it may only do this twice. If its above 50 or the truck is already warm, it wont shut off at all, just stays running like its supposed to.

I never have starting issues, never a hard start. New batteries, good cables, good glow plugs, etc, etc.

Truck is a 2000 F350 with 300k on it with good maintenance. tranny has about 60k on it, rear axle has about 60k on it, front axle was just rebuilt, new spring perch bushings, new readhead gear box, new tie-bar bushings, new swaybar and link bushings, new tires (and i checked the balance), new alignment, shaeffers 5w-40 syn oil with filter change every 5k,.....The only original parts are the cab sheet metal, dash, engine and transfercase.

Looking for help or advice on this weird problem......

 

Whenever I do a contribution test using my old Diablo Predator tuner, the only time I get any sort of reading is at idle only.
Soon as I raise the rpm the slightest little bit it goes to all 0%.

 

Sounds like the scanner isn't compatible with the PSD. No clue though. Here's a bump for ya.

 

What is a contribution test?

 

maybe you already did this but i think in order to do your contribution test the truck has to be up to a pretty good operating temp and you dont tuch the go pedal during the test.

 

A cylinder contribution test is a routine that tests how much work each cylinder is contributing.
A weak cylinder will show a percentage of rpm drop each time it fires.
A dead miss on one cylinder will show the greatest percent.
A weak cylinder will show less.
It's a great way to pick out a bad injector on the PSD.

 

OK thanks,i did this test but did not know what it was about.It said something about #8 cylinder after i did my injectors

 

truck was up to temp, was done at idle, was done my wrench with 12 years experience working st ford store on diesel trucks. Scanner is a Solus by snap-on, in the $2000+ range and has done the test on plenty of other PSD trucks in the same year range. The error is in the truck, not the mechanic or the scanner.

More info on the vibration - ONLY DOES THIS when the following conditions are met: speed between 30-40 mph, auto transmission in 3rd gear, will do the harmonic vibration during maintain speed, light acceleration or during downshift deceleration, AGAIN, ONLY at 30-40 mph and 3rd gear. Sounds more like a tranny or rear axle issue than an injector issue.

 

I know this is a stupid question but it couldent be your tires are out of balance?

 

I know that you checked the u-joints in the drive shafts. Did you also check the carrier bearing? The only other thing that I could think of was to verify that the front hubs are unlocking (front axle just rebuilt), otherwise your front drive shaft is spinning and may cause an odd vibration since it is being driven from the axles.

 

i have my own tire equipment. Real tools are an asset and I wrench for a living. Besides, the snap-on guy just lives a few miles away, this has been both a blessing and demise.....

Front axle shaft does not turn when its not engaged, lockout hubs are new, carrier bearing is new, tires are balanced (and NEW), New shocks, new calipers, now rotors, new wheel bearings.... Pretty much everything new. Check my tc nuts just to be sure, thats all tight, so is the tranny mount.

Im stumped.

 

Is it possible that you got a bad tire that is out of round? I had a friend that bought a car with a new set of tires. When he drove it on the highway, it vibrated severely. He later found out that the p/o had put a set of blems on it so that he could sell it.

 

and ask your neighbor if he can bring home an IDS scanner. and for the record my truck has a drone about that rpm range and i think its just the nature of the beast. i do have exhaust tho

 

Hey Jeffdoerr looks like you check just about every thing that could cause a vibration. In your first post you said you could feel it in your steering wheel correct? So to me your problem could be someware in your front end. Did you check your front tires? Had an almost similar problem where truck vibrates at low speeds. I would check tire for broken cords if they are not bad they could be hard to spot. Look at it eye level and look for imperfection or you could rub your hands across the tires . Hope this helps

 

Since you've pretty much replaced everything with new (tires, shocks, wheel bearings) I have to agree with you with leaning towards the tranny.
My ZF6 would shudder badly and only in OD and it felt like a U-joint had gone out. I even replaced all the U-joints and carrier bearing chasing the vibration with no improvements.
Replace the tranny and now it's smooth as silk.