So my E4OD when going 30-40mph will randomly rev up for a second or 2 then go back to where it was. Doesn't do it under hard acceleration but will with anything less then WOT, FIPL is new a couple months ago and properly adjusted.

 

find and clean all grounds that you can, associated with trans.

 

rev up how many rpms? as in the converter locks,unlocks then reengages type of rev? did it set code 62?

 

No flashing OD light, how high it revs depends on how long it takes to return to normal and/or throttle position. Typically 200-500 rpm. Original theory was torque convertor lock/unlock but lately Ive been leaning more towards its dropping into neutral then back into gear but truthfully couldn't tell you for sure.

 

does it bang back into gear? if it's slipping into neutral on it's own,the cause may be a failing MLPS (or just dirty connection at the mlps plug) if it's not banging upon re-engagement,and the the mlps is failing,then it will eventually and it's not good for the trans.be prepared to shift into N (quickly) and roll to a stop before placing the trans back into gear.

 

Definatly not banging into gear, just get the engine revving and if your accelerating itll have slower acceleration.

 

Hi, I have got the same issue with my 1993 E350 RV. Reving up 1-2 Seconds and goes back to normal again. Only happens when going steady in OD. No codes, no flashing OD light. Did you find out what causes this?

 

Nope, truck is rarely driven and seems like everytime I ask this question I got different answers so it got relegated to the back of the priority list (also partly due to the fact that what I normally use the truck for this is a non issue)