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: :welcome:

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 :)

[SergntMac]

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. First, the '03 Marauder has the 4R70W tranny. The '04 has the 4R75W tranny, and improved torque converter.

It's not a gear, but an OSS sensor (7M101) in the tranny that feeds shaft rotation data to the PCM, as well as the instrument cluster. Here it is directly from the BRB...

"The frequency from this sensor supplies the PCM with output shaft speed information. This information is used in determining shift scheduling, torque converter engagement schedule and E(lectronic)P(ressure) C(ontrol)".

Likewise, the ABS control module collects rotational data from each wheel sensor and sends that to the PCM. It does not act on that data alone, it's just a "switchboard". The PCM does the thinking on this data, and sends out further instructions to other sensors/controls when the data doesn't match, or, indicates a problem. As far as I can tell, the signal sent to the instrument cluster via the ABS control module is to illiminate MILs and other warning devices after the PCM calculates an error. It may also feed the speedo, which looks like a clock mechanism with it's own solenoid driving the gauge in a sealed independent unit.

I don't think you have a bad OSS, but it's possible. My first suggestion still sounds the most likely, i.e. that the PCM has been told to think there is a taller gear in the rear end, and it's not there.

If the previous owner used an aftermarket HHP to reset the native shift schedules and TC lockup, most of these aftermarket tuners come with three programs. One for performance, one for lower octane fuel, and one for performance with speedo correction for taller gears, usually 4:10s. The previous owner may have used that program to tune his Marauder, and didn't reset it before selling the car.

I had a similar problem with the OSS when I switched to the '04 MAV2 EEC. It was programmed for data from the 4R75W tranny, and set off a "slipping" signal to the dash (flashing OD indicator) when the data didn't match. Jerry slapped himself upside his head with "*****, forgot about that" and fixed it with a few keystrokes.

Hope this helps, it's the most likely of possibilities.

[Grifter]

Thanks. I did not know that the 4r75w started in 04. Good to know.
sounds like the problem will be reconciled when i get my own tune put into the vehicle.

[RoyLPita]

Aside from 22 inch wheels...

Speedo issue...

Hopefully you still have a bit of warranty.;)

BTW: :welcome:

And where abouts are you greeting us from?

22's?? What is the tire size in relation to the stock rear height?

[SergntMac]

"Rut-Row". I read stock tires in the opening post. If there are 22" wheels on this MM, forget everything I suggested.

[Grifter]

no, i dont know where the 22" wheels comment came from either. I indeed am still runnning stock tires.

[CRUZTAKER]

That would be me...I mentioned as them (22's) as a facecious suggestion that larger wheels would throw off the speedo in the opposite direction.

:hide:

How'd that song go....?

I was gonna try to say something witty...but then I got high....

[RoyLPita]

That would be me...I mentioned as them (22's) as a facecious suggestion that larger wheels would throw off the speedo in the opposite direction.

:hide:

How'd that song go....?

I was gonna try to say something witty...but then I got high....

Back to square one.

Have the "tune" checked.

[Grifter]

is there anything i can datalog that will give me a definite yes or no about whether or not there is a tune in there?
i still have my xcal2 left over i can log with..

[jdando]

is there anything i can datalog that will give me a definite yes or no about whether or not there is a tune in there?
i still have my xcal2 left over i can log with..
You may want to download the SCT Livelink software

http://sctflash.com/downloads.php

This in combination with the XCAL II can do datalogging and may tell you what is going one. My experience with this setup is minimal and it was a PITA . The system was not that user friendly and crashed a lot.

Also PM HookedOnCV. He has a ton of experience with the software and is also in the western suburbs.

jeremy

[Grifter]

i used the xcal on the Mark alot to log things, i never had a problem. I thought the interface was rather friendly and pretty easy, but thats me, i'm a computer geek.

[SergntMac]

Here's some advice from my "if it were me" bin.

First, I would contact an SCT dealer and ask him to recycle your XCal tuner, clear the VIN block from your Mark. Then purchase a custom tune for your MM with 3:55 gears, and flash that to your Marauder.

If the speedo corrects, you have your answer, and problem solved, as well as a fresh tune for your Marauder. If not, you have at least ruled this out and you can seek other remedies on the speedo issue. Either way, you have a tune you own, and a tuner that will work on your Marauder.

If the previous owner installed a custom tune, you really have no idea what's inside, and this could continue to haunt you every time you are troubleshooting a problem. Best to clean the slate, yes?

I think Dennis Reinhart can help you, call him at 904.276.5003?

[KillJoy]

Here's some advice from my "if it were me" bin.

First, I would contact an SCT dealer and ask him to recycle your XCal tuner, clear the VIN block from your Mark. Then purchase a custom tune for your MM with 3:55 gears, and flash that to your Marauder.

If the speedo corrects, you have your answer, and problem solved, as well as a fresh tune for your Marauder. If not, you have at least ruled this out and you can seek other remedies on the speedo issue. Either way, you have a tune you own, and a tuner that will work on your Marauder.

If the previous owner installed a custom tune, you really have no idea what's inside, and this could continue to haunt you every time you are troubleshooting a problem. Best to clean the slate, yes?

I think Dennis Reinhart can help you, call him at 904.276.5003?

I would also suggest to get a 4.10 Tune at the same time.

KillJoy

[Grifter]

i agree its best to start with a clean slate. and thats what i am pursuing. I have talked to my tuner, and he says i need to send it to SCT to clear it so its a fresh xcal again.