Hey guys, kinda stumped here. I thought changing gears didn't have any affect on the speedometer? I changed from 3.73's to 4.10's in my '03 E250. My speedo is off by at least 8-10mph at 70mph now. Crazy part is, it still governs me at 89mph even though I know I'm only doing about 75 which is not gonna work for how much interstate driving I do.

Is there different tone rings for different gear ratios in these vans? Do I need to find a '03 E350 computer? How else can this be fixed?

Thank you in advance!

 

the van tells you the speed based on transmission output shaft speed. But it doesn't know you changed the ratio.

In the old days you would have to change the speedo cable gear but I don't think your 03 has that. I think you're going to have to get a "tuner". Everyone here like Mikes 5 Star. It's basically your only reasonable choice.

Prepare yourself for a LOT of responses to your post. Lots of good advice will follow; from van guys with lots more experience and knowledge than you and I


It is governing you to 75mph because it thinks you are going 89.
Changjng to a E350 computer won't help. Unless you find a 2003 e350 computer from a van with 4.10 gears. And even then, I don't think it'll work.

 

I think most all 350 vans come with 4.10's which is why I'm wondering if I can't just swap that out for $35 from a local Pull N Pay. I wonder what years will interchange correctly with my 5.4 / 4R75W / 4.10's. I don't mind doing a tuner if I have to but $35 ECU would be easy and cheap.

 

My 07 E350 has 3.73's

 

My 2000 E350 has 3.55's.

 

mine has 4.10's

 

Guess I'll be searching hard to find exactly what I need. All the 350 vans at my company are "super duty" and I know they have 4.10's. What brand of tuner has van tunes and speedo recal stuff?

 

mikes 5 star is the only way to go.
So sayeth the crowd on this forum.

 

Thanks for the tip, I'll look it up later. I did some programmer research yesterday and kinda limited it down to the hypertech 742500 speedo fix $229, or the hypertech 42500 speedo fix + tuner for $299.