Odd accelertation/decel problem

[nvrsatisfied84]

Ive noticed before on the interstate and odd problem while running 75-80ish that the truck will accel and or decelerate 2-3mph by it self while no terrain changes, wind or pedal pressure changes. Its been a on going thing it did it coming home the day I bought it 3yrs ago 1 time in a 4 hour trip completely stock and randomly here and there since usually only after high speeds for atleast an hour. Did it sat twice back to back and its never done it b4 just would like to know if any one had this happen?

Spec 08 F-450 4:88 125xxx had new motor and turbos at 90xxx fully ******d S@B intake 4" dp back Spatan 210 tune 22.5s

tried to watch gauges but it happens soo random and fast its hard to catch any changes in rail pressure boost egts vgt all seem normal but like said its a spilt second and goes way feels like boost lost and boost pick up like maybe vgt spazzing or something idk I hope you understand and can help thanks

 

[Bigboytoys]

Is this in fairly cold weather? Any codes?

Next time this happens watch the drive pressure, EBP, to see if it's going up when the truck acc's, if no change then there might be the issue.

 

[nvrsatisfied84]

No codes and ok ill try to watch it then and it was around 40 degrees what do u think may be happening?

 

[Bigboytoys]

Your not in cold enough weather for the issue I was thinking of.

How long since you changed fuel filters or reflashed the truck?

Another possibility is to watch the VGT % and the throttle % while this happens but you'd have to be running by foot cause running cruise it'll be 0.

If the VGT is acting up the % will change a fair amount, 15% or better.

The peddles 3 potentiometers are suppose to be monitored by the PCM and if they aren't reading the same the PCM should set a code but this doesn't always happen if it's a wiring or connector issue.

 

[nvrsatisfied84]

its been almost a yr on filters and flashing almost 5000ish miles ago its about time to change oil and filters
I watched vgt % but not throttle tell after it acted up like I said very random and its like a spilt second thing so it hard to see gauges at exact moment it does it. It hiccup's and it over and I was not using cruise when it did it but it was on earlier in trip

 

[Powerstroke Man 6.4]

its been almost a yr on filters and flashing almost 5000ish miles ago its about time to change oil and filters
I watched vgt % but not throttle tell after it acted up like I said very random and its like a spilt second thing so it hard to see gauges at exact moment it does it. It hiccup's and it over and I was not using cruise when it did it but it was on earlier in trip

I would watch rail pressure, vgt dc, ebp, boost and throttle percentage