speedometer is off

[Grifter]

The speedometer in the Marauder is off. It reads 15% slow. What would cause this? all of the tires are stock sizes, i dont know if the car has gears in it or not, i believe it to have some kind of flash tune based on ths shift firmness. I would think the speedo on this car is run off the ABS sensors, not the OSS gear.

Any thoughts on why it would be off?

[KillJoy]

My Thoughts:

Non-Stock Tire Size
Non-Stock Gearing
Aftermarket Tune designed for one of the above
Faulty Sensor / Gauge

KillJoy

[FordNut]

It does not use the abs trigger for speedo. It uses tranny signal.

[Breadfan]

I'd say you may have different gearing. However you say you have a tune...usually a tune would compensate for that, unless the tune was installed first and never updated for the new gears.

You can determine the gear ratio by putting the rear in the air (preferrably with a jack or lift, not Dukes of Hazzard style...), put it in neutral, spin the rear tire and count the number of driveshaft revolutions.

I believe the driveshaft would spin more than the tire. So, for one full revolution of the tire, stock gears would spin the driveshaft 3.55 times. If it spints 4.10 times you may have 4.10 gears.

Where did you buy the car? Do you have contact with the original owner to inquire?

[Grifter]

From a dealer in Burnsville, MN. i know the previous owners name, but nothing else.
I will throw the car in the air and see how many turns the DS makes in teh coming days.
but the gears makes sense with the way the car acts. to determine the speedo was off, i drove past 2 miles worth of miles markers on the road. the tripometer was .3 off at the end of the 2 miles. (~15%)
the car shifts out of first late like my Mark VIII did after i did gears in that, before i got the proper tune to compensate.

[KillJoy]

Looks like you may just have 4:10's in it.... apparently the previous owner never cared about the Speedo being off.

If you got the Tune, contact it's creator, and see if they can send you another tune for 4:10's.

Another thought: If you got the Tune yourself, any chance the Vendor sent you multiple Tunes, and you perhaps installed the incorrect one?

KillJoy

[Grifter]

i didnt purchase the tune for the car, (if there is one) it was in there when i bought it. i do have the Xcal2 left over from my Mark VIII, i can get a hold of Torrie at FPN and see what he can do about getting my Xcal setup for the Marauder now.

If it does turn out that I have 4.10's back there, what speedo gear do i need for the tranny since its obviously off.

[Breadfan]

No need for a tranny gear, the tune will take care of it.

Contact Lidio or Reinhart, they both make tunes for the Marauder.

You can search around and see the difference between their tunes, but both can calibrate for 4.10s.

Since you already have an Xcal2 you can probably get a tune at a different price than if you bought the Xcal2 from them...ie. lower.

[Grifter]

Thank you. i will check to see what gears are back there. Even if i have to do it the old fashioned way, and rip off the diff cover and count teeth.

[KillJoy]

Mmmmmmm......Gear Lube.....

KillJoy

[CRUZTAKER]

4:10's would make the speedo read like 90 when you were doing 70.
I made the drive home from PA back in 2003 with gears and no tune.
It's not the gears.

[Grifter]

your right, i didnt think about that much. gears would make the speedo off the other way.

so that leaves us the original question.

[CRUZTAKER]

Aside from 22 inch wheels...

Speedo issue...

Hopefully you still have a bit of warranty.

BTW:

And where abouts are you greeting us from?

[SergntMac]

IMHO, if the speedo is slower than the actual movement of the car, your aftermarket tune may be compensating for a set of gears not installed in the car.

There is no speedo cable, or, speedo gearing in the tranny, it's all electronic The signal is sent to the speedo electronically, where that mechanism operates like a clock. It's a sealed unit, nothing to adjust or change, replaced as a whole unit.

[Grifter]

theres not even a OSS gear on the tranny like previous 4r70w's? (yeah i know, we have 4r75w) I keep referring to my Mark, but its the car i know alot about, but on the Mark, there was a OSS, it controlled shift points and just referenced the speed of the Output Shaft to the ECU. The speedo was actually referenced off the ABS sensors.

I am in the Minneapolis MN area, western suburb on Lake Minnetonka if you have any clue where that is