Owing a '00 Expy 5.4L with stock 255/70R16 tires, I am thinking about upgrading to 285/75R16 tires on the stock rims. Obviously, this is going to throw off my speedometer. My questions are:
1) Does the Superchip recalibrate the speedo automatically?
2) Or, do I pull the chip, get the Ford dealer to recalibrate, and re-install the chip?

Any and all help is greatly appreciated.
Thanx.



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2000 Wedgewood Blue Expy XLT 5.4L 4WD, C&C group, towing package, beige leather interior, captain's chairs, 6 CD Changer, 255/70R16, all-weather floor mats, factory fog lamps, Mobil1 5W-30 Synthetic w/ Puralator filter

MODS
Ford Bug Deflector (2/15/00), Superchip (3/11/00), Airaid (3/23/00), Edelbrock IAS shocks (3/23/00), Jardine cat-back exhaust (4/6/00, removed 8/22/00), Under Seat Locking Storage Drawer (6/6/00), MPC Rear Air Foil (7/2/00), Super-White Headlamps and Foglamps (1/15/01)

 

Hi jmartinb,

No, the Superchip can't "automatically" correct the speedometer, it's programming cannot ever change on it's own, we have to have it manually changed.

I think you're going to find that your dealer can't do it, either. But if they were to say they could, then you'd need to remove the Superchip so the internal EEPROM is switched back on and made available to their SBDS system. Then when you put the Superchip back in, you wouldn't have those changes anymore, as the computer would be getting it's instruction set from the Superchip once again.

Since you're using the Superchip, and it's a 1999 or newer model (in your case, a 2000), the only way to do this is in a custom program for the Superchip. Starting in the 1999 model year, those vehicles no longer use a standard reduction gear in the tailshift of the transmission, so it can only be done in the program. All a dealership can do is to load a program for a different gear ratio, say for example load it with a program for a 3.31 gear or a 3.73 geardhch way your error is, instead of 3.55's, or something along those lines, they do not have the ability to just dial in a speedo for error correction, all they can do is load different factory programs for that same vehicle with a different gear ratio, basically lying to the SBDS system in an effort to force the speedo compensation. But that too is a mute point, since you're using the Superchip, it has to be done in the Superchip.

You'll need to determine the amount of speedo error after installing the tires, and then we'd do a custom program to compensate, assuming we can do that for your particular computer code, that's an on-going R&D project, and a number of the codes we can do. I would suggest touching base with us, and let's check to see if we can do that for your code.

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Mike Troyer
Performance Products, Inc.
National Distributor of Superchips
(540) 862-9515
Email: mtroyer@compuserve.com
Performance Products F150Online Superchip ordering system: F150Online Superchip Ordering System
First National F-150 Online Rally Event Organizer

 

Mike-
As usual, thank you very much for the detailed response. As I get closer to changing tires, I'll call your company with the engine code. With any luck, you'll be able to customize mine for the new tire size.

Once again, you've got a great product, and I get as much enjoyment out of it now as I did when I first installed it.

 

your dealer can reselect the tire size using the wds, it changes the tire from what the vehcle should be equipped with ( on your vin label on door) to what u are putting on, they must use a pcm reprogramm label and make note of the changes. The wds has actually tire sizes of wich they can use or u can manually calculate it by the number of revoulutions per mile of the tire, wether the aftermarket chip will interfere or not i do not know but i do know that the dealership can do this

 

Mike I just put on 285-75-16's on my X. I had 265-70-17's on before which is 1.1" smaller than my 16's now. I do feel a little loss of low end power and I also wonder if you could recalibrate my superchip also? I do have 3.73 gears. And yes my speedo is off but I'll take care of that later.

Thanks

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99 Expedition XLT,5.4L,4X4,3.73LS,17"AT/S,Airaid Intake,Superchip,Custom Edlebrock shocks,Dynomax Super Turbo 3",Helwig Sway Arm,Polk speakers

 

Hi hdlouie,

There are a couple of points to make here, if I understand your question correctly, so please bear with me.......

Only the speedometer calibration that needs to be changed in your case, so if you aren't worried about that, there is nothing else to do usually.

You see, the ECU gets it's primary vehicle speed data from the VSS (vehicle speed sensor system), but it also looks at numerous other data streams to confirm that data, such as engine rpm, output shaft speed, etc. If the speedometer is accurate, then the ECU uses vehicle speed (mph) to determine it's shift points. If the speedo is off, which the system will know as there will be a conflict between VSS and all the other data streams used to confirm VSS, then the ECU will default to using engine rpms to determine it's shift points. With such as relatively small size difference, 1.1 inches, the system should be easily able to handle that, and your shift points should be just fine. If not, sure, we can usually do a custom program.

However,there is nothing we can change in that program to get you even more power than it's already adding, to compensate for those larger tires, if that is what you mean, as if we did, you'd get detonation. If you didn't already have the Superchip, then adding it would be an excellent way to compensate for the effective power loss from a 1.1 inch tire height change, but since you already have the Superchip, we can't go in and pull even more power out of it using the same 92 octane fuel, as that would throw you into detonation. Let me know if I've not understood your question properly.

If you'd like to go over this in more detail, as always, please feel free to give us a shout via phone or email, ok?

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Mike Troyer
Performance Products, Inc.
National Distributor of Superchips
(540) 862-9515
Email: mtroyer@compuserve.com
Performance Products F150Online Superchip ordering system: F150Online Superchip Ordering System
First National F-150 Online Rally Event Organizer

[This message has been edited by Superchips_Distributor (edited 02-15-2001).]

 

Thanks for the info. I'll keep everything the same.

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99 Expedition XLT,5.4L,4X4,3.73LS,285-75-16 KO'S9(old 17"AT/S),Airaid Intake,Superchip,Edlebrock shocks,Dynomax Super Turbo 3",Helwig Sway Arm,Polk speakers