2003 FX4. 142K on it. Do these trucks have trans-slippage problems or LSD problems as they get high into the miles?
I've owned it since new and have had the trans/transfer/etc fluids serviced on schedule. Lately as I am coasting after hard acceleration the truck seems to slip and "jerk" for a split as I get back into the gas. Usually happens around turns and seems to be only when its colder out. The trans shifts fine from a standstill as well as into cruising speeds so I'm leaning towards a LSD problems. Just curious if others have run into this or something like it

 

mine sort of does the same. not sure if its good, bad or normal either.

 

you may not have a tranny or LSD issue.
Although...if the differential fluid hasn't been changed yet....might be a good thing to do. if your unit has the LS diff..be sure to get the friction additive, when refilling.

Now....studering/ hesitation/ jerking that your experiencing maybe related to 1 or some of the COP's (Coil On Plug) going bad...no they won't trip a code until they are really bad
the real clue is if it does it under light acceleration...clears up under moderate to heavy accelerationand preferrs to show up within certain MPH ranges (like 40-60mph)

it certainly could be other things...but start there...seeing if any codes are present wouldn't hurt either

 

Mine broke the clip that holds the clutches for overdrive.
Trans has to come all apart to fix so I had my trans man do a overhaul with upgrades for future horsepower!

 

I have had the same issues you're talking about since around 85,000 miles, only difference is that mine does it regardless of temperature. Other than that, it's the exact same, rolling into corners or coasting and then getting back on the throttle and the transmission seems to slip. I doubt it's an LSD issue as I have an open diff. I have 123,000 now and it doesn't seem any worse. I'm just going to drive it 'til it goes.

 

Clutch pack/ Trans mount.

 

Thinking clutch packs as well although upon further trouble shooting (driving) I'm leaning towards the converter. Shifting is fine but I can feel the converter trying to lock/unlock at lower than normal speeds. Going to have it looked at after the holiday and probably rebuilt. Thanks

Oh yea...the COP's were new last year


To Mozzy..... mine is doing it in all temps as of late too so we'll see