Acceleration Problem

so i have a 1999 ford e-450 cube van its the v10 gasoline, and basically when you push on the gas it revs high but moves slow, if i push the gas all the way down it revs high but it will take long to gain speed probably like 1 minute to go from 0km to 60km! what could be causing this?

i changed

i have cleaned out the gas tank

- replaced the gas pump

- replaced the fuel filter

- replaced the fuel injectors

- replaced a few coils

- replaced spark plugs

- flushed all the fluids and replaced with fresh fluids

- oil change

- had it checked for vacuum leaks, there are none

- put a new battery in

- replaced the diff press feedback egr sensor

and still nothing!

only codes left is a

p1401- diff press feedback egr circ high input

p0171- system too lean bank 1!

please help

What you’re describing are the symtoms of a slipping transmission. Have you’ve checked the level/condition of the tranny fluid?


If the engine revs and the van doesn’t move much, then this is likely a transmission problem. The more you drive it like this without having it checked out, the more damage you’re probably doing. Do you have the correct transmission fluid level? Is the fluid pink and not burnt-smelling?

we drained the fluid (only from the transmission pan) and refilled it with new mercon about 6 liters but didnt do anything, its almost like we only started having this problem once we changed the fluid

i believe i have the correct level, i did drain the transmission oil from the pan and it was black! i almost though i drained my oil, so i put in new red mercon, and it didnt seem to help at all

Black transmission fluid = burned up transmission.


it was really dark but it didnt smell burnt, it just hadnt been changed in years

In that case, you’ll probably end up taking all the money you saved by not changing the fluid on schedule, adding a lot more money, and having your transmission rebuilt.

it was my uncles it sat for a year so i had no history of the vehicle, i just got the vehicle and changed all that, only had it for a month, its the last owner who messed it up, might just scrap it cuz ive blown over like 2500 so far on repairs and a tranny repair will just top it up