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Discussion Starter · #1 ·
Hi,
I'm new to the forum. I have a F150 lifted truck I built myself. My boyfriend has the 2001 F250 7.3 powerstroke. I know NOTHING about diesels so I need some help.
He purchased a SCT programmer Saturday. The guy told him it would correct tire size which it doesn't. According to SCT the tire/speedo/gears are NOT controlled by the PCM but by the speed control box.
His stock tire was 265/75R/16's. He's only running a 315/70R/17 tire.
Is the tire difference a big deal? Was the SCT guy correct on the PCM?
As far as I know it has not been regeared. I think the stock gears are 3.73's.
Any advice?
Thanks,
Christine
 

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You can have the dealer retune the GEM module to tires up to 35's (315's). They will charge about one hour of shop time to do this...
 

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John Wood Nut Swinger
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Discussion Starter · #4 ·
We stayed with the SCT programmer because no programmer will change the tire/gear set up. That is run by the GEM where the programmer only affects the PCM. I think we've got 3.73 gears. I don't know if it's worth it, or needed to regear to 4.10. What's your opinion on that? Thanks.
 

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Not worth it IMHO... I am running 37's with 3.73's and no issues.
 

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it easy to recalibrate the speedo,took me about 2 minutes,the spped change could prolly get up to 8 or 9mph at higher speeds.
 

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Discussion Starter · #7 ·
I'm not so worried about the speedo. It's running about 4 mph faster at 65 mph. I'm trying to eek every mpg I can since diesel in SoCal is $5.40 a gallon. I was wondering about gears on mpg and tranny wear.

Is the speedo recalibration a DIY project?
 

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John Wood Nut Swinger
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I'm not so worried about the speedo. It's running about 4 mph faster at 65 mph. I'm trying to eek every mpg I can since diesel in SoCal is $5.40 a gallon. I was wondering about gears on mpg and tranny wear.

Is the speedo recalibration a DIY project?
Yes, If you are a ford tech and have access to the dinosaur of a tool required. Maybe you know somebody that works at a dealer? A friend is how I got mine recalibrated.
 

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no need to regear until 38"+ tires. tranny is gonna push his tires easily. You won't get an accurate mpg reading with a speedo that is off, so you cant really calculate that until the speedo is fixed, or you use a gps of some sort. There are I think 4 options for getting the speedo where it should be. All are around $200 excluding the Ford option, which ranges from $50-$100 depending on who you go to.
1. Ford - can only do up to 35" tires
2. Truspeed by Superlift - TruSpeed™ Speed Sensor Recalibrator · Superlift · www.superlift.com
3. Respeed by TS performance - http://tsperformance.com/respeed.html
4. Speed Wizard by Merlin - Speed Wizard Speedometer Correction

have Jody at DP tuner get some tunes for ya for that SCT. your b/f will be on cloud 9 until he gets used to the power. Theres also a nice economy tune he can get for ya.
 

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it easy to recalibrate the speedo,took me about 2 minutes,the spped change could prolly get up to 8 or 9mph at higher speeds.
yes, its easy in a 97, but not a 2001
 

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thanks sirn, if anybody has questions on the speed wizard just email me [email protected]

I am here to help people - i try to visit all these sites and help people with questions on speedsignal but theres 1 of me and many of you all

kenny
 
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