Have a weird jerking feeling at 45 mph. Could this be a transmission issue?

 

Do you have any gauges that read live data, like the scan gauge II or one of the smartphone apps like dashboss for IOS devices or torque pro for android? Have you had it scanned for DTC's? Also what year is your truck? And I do not believe it is a transmission problem.

 

Sounds like injectors to me......or FICM problems.

 

Just bought a scangauge II this week. Haven't had a chance to program it yet. I did download the x gauges for a 6.0.

 

As the saying goes "what are ya waitin on son? Get er done"

 

Truck new to you?

Both the shortbed and longbed exhibited bouncing or "bucking" from either improper pinion alignment in the short beds or carrier bearing in the long beds.

If it's only when cold, that's injector stiction which rears it's ugly head when the tranny goes into overdrive at about 45 mph.

Josh

 

Whats the tac say when its doing it, is there an rpm surge?

 

No RPM surge. Scangauge shows FICM main power to be approx 48.5 at OT.

 

I have the exact same symptoms. Got it checked out yesterday and I need to replace the #2 & #4 injectors. Truck runs fine after warmed up. Usually about 10 minutes to run perfect.

 

Did you just disconnect the batterys per chance? And is the jerk on a shift? like the 3rd to 4th shift? If so preform the trans relearn in the tech folder.

 

Mine has always done this. 1200RPM / 45-46 MPH shudder in overdrive.

It's not an injector issue on my truck. There's a TSB about swapping rear axle spacers to help with the issue.

To clarify what mine does: If I accelerate thru this area to a higher RPM/MPH, everything is smooth. Under steady driving conditions, as I ease up to 45-46 MPH it'll shudder. If I just speed up a bit beyond this, it smooths out.

It just seems to hit resonance at this speed. If I put it on tow/haul, I can still feel it in a lower gear when I get to that speed. I can also pop it into neutral and coast, and it'll do it as I coast thru the 45MPH area.

Shudder on Acceleration:





On trucks with single driveshafts, check the rear axle spacers. If the spacers are installed with the thin

side (1 7/8") facing forward, they should be reversed (swapped left to right) so the wide side (2 1/4")

faces forward. If the truck now only shudders with a load, swap out the spacers with 2" flat ones from an

F250 long wheel base (two-piece driveshaft), P/N 2C3Z-5598-PA.




99-07 Super Duty F-Series Two-Piece Driveshaft Shudder:





Some trucks may exhibit a vibration on moderate to heavy acceleration from a stop. This is usually due

to too high of an angle through the center u-joint. The correct angle through the u-joint should be 0.5-3.0

degrees (compare front shaft angle to rear shaft). Check the engineering number of the center bearing

bracket to ensure it is the correct application, and replace if necessary. If the bracket is correct, the

shudder may be corrected by shimming the bearing down from the bracket using up to three 1/4" shims,

part number E0TZ-4A209-A and two grade eight bolts long enough to expose three threads above the

nut when tightened to 46 ft/lbs. Loctite is recommended. Broadcast Message 0518, 1475; TSB 04-22-7,

05-17-6, 06-23-4

 

Was told by Tyler Fuel Injection that the PCM is going out. I'm not convinced so will let it ride for a while. Scanguage shows good voltage on FICM and no codes. Thanks for all the suggesstions!

 

It's NOT the PCM. You need to get something that will scan for the transmission codes, but it's most likely injector stiction.

 

I'd run one of the brands of additive that cleans the injectors before I'd commit to any kind of repairs.... lots less $$$ for a possible gain!

 

I know a guy that his done about the same thing,low rpm up a little grade around 40 or 45 mph,he done the blue spring upgrade and cured it.