Speedometer problem E250, 5.4l

[wr2nxt]

Speedometer problem E250, 5.4l
We just completed a UJOR kit on a 1998 F250 Sportsmobile. I put 35 in tires on it. We cant get the speedo to read properly. When the speedo is hooked up without the Abbott Electronic ratio adapter the speedometer works (although it reads inflated speed due to tires and shaft changes),but it does read up to about 30 mph any faster and it pegs the speedo. So we hook up the Abbott and it doesnt read until about 35 mph then it reads accurately up beyond highway speed. When it is in this condition the van will not shift properly below 35 mph.
We have changed the VSS on the tranny, we have tried a different Abbott ERA.
Our connections have been soldered to minimize signal loss.
Any ideas from the Forum will be welcomed..

[BajaSportsmobile]

Where is the VSS located - exactly.?

[wr2nxt]

the vss is between the transfer case and the tranny. We changed the output shaft to accept the transfer case.

[MadScience]

When you say between, you mean the normal position on the transmission output shaft? On the top back of the transmission?

FWIW, the improper shifting is a side-effect of not having the correct speed reading on that van (well, it is on a 99).

The fact that it seems like you are getting two different rates of signal out of the vss seems odd. It makes me wonder if there isn't something physically broken or dirty on whatever drives the magnets past the sensor. Since it's on the top, you'll need a mirror or a camera to look into the hole, but you can generally see the sender rings go past if you look in the hole with the sensor removed.

I would also talk to whoever changed the output shaft. (At least on the 4r100 that's pretty involved.)

[BajaSportsmobile]

Did the cut the tone wheel down to three teeth?

[wr2nxt]

I don't understand your reply a s to cutting the tone wheel.

[MadScience]

The tone ring is just a ring with teeth and gaps:



It turns past the sensor and for each tooth standing up you get a pulse.

The fact that your pulses do not just linearly relate to the speed of the output shaft is what's confusing.

[wr2nxt]

Our next step is to scope it while it is rolling, I will post the results, Thanks for your help with these gremlins.

[wr2nxt]

Originally Posted by BajaSportsmobile

Did the cut the tone wheel down to three teeth?

No we did not, i think it has 6 or 8 teeth

[BajaSportsmobile]

If you want to call me this morning I can try to help.

Agile Off-Road (619) 663-5493