Ford spedo calibration

[jbiersba]

not sure whether it's worth fighting over. the dealer did perform the service they said they would.... I assumed it wouldn't be an exact match, I just didn't realize it was already pretty close to the limit. The strange thing is that the stock tires that came on the vehicle were about 33"..... it's odd that there is this little adjustability in the "module".

As far as inline devices go, I haven't looked too hard, but I think it's been discussed that there are no inline devices available for this model.

[Dusten]

yes and no. anything that reprograms the computer to think it has bigger than 35's will trip the abs light. the devices they are talking about take the signal from the vss and change it, so the computer see what it wants. i dont like this idea, its not a true fix, just a fooler.

[Mercury]

Fkirst Jbier... i said this a few posts back, maybe you missed it

"I do not visit all the forums as often as I should, but yes there is a inline device that will work on the 08 F250, as a matter of fact there are many on F450's from 2008

as for programmers, i do not know of any, but for inline devices....

speed wizard by merlin controls I would think the truspeed would work as well but I hear people say no it don't....

kenny "

Originally Posted by Dusten

yes and no. anything that reprograms the computer to think it has bigger than 35's will trip the abs light. the devices they are talking about take the signal from the vss and change it, so the computer see what it wants. i dont like this idea, its not a true fix, just a fooler.

LITTLE LONG SORRY ABOUT THAT>>>


Dusten, would you care to elaborate on why an inline device is not a "true" fix, in essence you are doing the same thing as reprogramming the computer...

instead of 1 revolution = Y pulses you are making 1 revolution = Z pulses.

I have witnessed more people have more success with inline devices then I have ever seen with programmers and dealerships, at least for getting the speed signal to be accurate.

to bring up another question... if ford offers an off road tire that lets say has a 1" larger diameter, do they then reprogram those trucks for the new size? I am 95% sure they do not, so all those people are riding around with the wrong speedo... As a matter of fact, take a stock truck and compare it to GPS, mine was off by about 2% to start with STOCK.

so to call a inline device a "fooler" may be an ok statement, but then a dealership can be called a fooler too by fooling the computer into thinking it has something other then stock.

Also with an inline device the VSS is not changed directly, it is the signal AFTER the ABS module that will be modified, the VSS is only one part of 3 sources to tell vehicle speed; at least based on my experience.

I would be open for discussion on this, the speed signals on these trucks fascinate me, so i am always open to learn something new.

kenny

[Dusten]

Originally Posted by Mercury

speed wizard by merlin controls I would think the truspeed would work as well but I hear people say no it don't....

kenny "

they dont even sell a tru speed for our trucks. and all the other reprogram style only correct to 35" tires.

Dusten, would you care to elaborate on why an inline device is not a "true" fix, in essence you are doing the same thing as reprogramming the computer...

instead of 1 revolution = Y pulses you are making 1 revolution = Z pulses.

i would love to elaborate, as in essence, you are not doing anything close

it isnt the same, because much like a mass air flow extender on high horsepower cars it doesnt reprogram the computer to understand what is going on, it changes the signal to the computer, so the computer is happy.


Its an interpreter for lack of a better word. instead of you learning spanish to talk to your neighbor, you hired someone to stand on the fence and shout back and forth between the two of you.

to bring up another question... if ford offers an off road tire that lets say has a 1" larger diameter, do they then reprogram those trucks for the new size? I am 95% sure they do not, so all those people are riding around with the wrong speedo... As a matter of fact, take a stock truck and compare it to GPS, mine was off by about 2% to start with STOCK.

you are correct, ford does not change the calibration based on what tires are on the truck.
2% is an acceptable error, that means when your speedo reads 60mph you are going *gasp* 61.2.... or for every 100,000 miles, you are really going 102....
My speedo with 37's is only off by 10%. But, i have stopped using it, and just use my gps for speed anyways

so to call a inline device a "fooler" may be an ok statement, but then a dealership can be called a fooler too by fooling the computer into thinking it has something other then stock.

they arent fooling anything. the computer knows that your tires makes X revolutions per mile, so you tell it that now, they take Y revolutions. that isnt fooling anything, that is telling it the parameters have changed.

[Mercury]

Originally Posted by Dusten

they dont even sell a tru speed for our trucks. and all the other reprogram style only correct to 35" tires.



i would love to elaborate, as in essence, you are not doing anything close

it isnt the same, because much like a mass air flow extender on high horsepower cars it doesnt reprogram the computer to understand what is going on, it changes the signal to the computer, so the computer is happy.


Its an interpreter for lack of a better word. instead of you learning spanish to talk to your neighbor, you hired someone to stand on the fence and shout back and forth between the two of you.


you are correct, ford does not change the calibration based on what tires are on the truck.
2% is an acceptable error, that means when your speedo reads 60mph you are going *gasp* 61.2.... or for every 100,000 miles, you are really going 102....
My speedo with 37's is only off by 10%. But, i have stopped using it, and just use my gps for speed anyways

they arent fooling anything. the computer knows that your tires makes X revolutions per mile, so you tell it that now, they take Y revolutions. that isnt fooling anything, that is telling it the parameters have changed.

Good post dusten, I appreciate your in depth description

I will say however, since the programmers do not do over 35, then isn't the only option an inline device?

I thought Truspeed did make them for the 08, I know speed wizard is on many 08's and no problems.

From my experience, I have a 2003 F250 5.4L gas engine, my computer was programmed from the factory with 31.7" tires (stock ones) i never had the computer re-programmed EVER, other then me using my tuner to change tire size (which did nothing by the way)

The engine or tranny on my truck does not use "speed" from the ABS module, and as a matter of fact (i have spent a lot of time researching this), based on my research, the only ford engine / tranny from 99 04 that does use the speed signal is the 7.3L, but when you correct the signal in the right spot (before it gets to the engine/tranny) then the engine/tranny will use the correct value.

What about on the older trucks, when no computers were even involved... the speedometer was corrected by a speedometer gear, this method has worked well for many years, to me an inline device is doing in essence the same thing.

It is changing the amount of pulses PER revolution, and that is what the reprogramming of the computer is doing.

Sure I have to agree that when you use a programmer the computer knows how many pulses per revolution it is getting, and it is the right value. But is there any functional difference between that and just sending the computer a modified value?

When you put larger tires on you the same pulses per revolution as before but you will travel more distance (therefore 30mph as indicated is actually more)

change from 31.7" to 35.5" thats a multiply factor of 1.1198 lets call that 1.12

So what the inline device does essentially is where it used to be 100pulses/sec for 100mph actual, it will will make it 112 pulses per second at 100 mph - this makes the speedometer read correctly.

It sounds to me like you have something against in line devices?

they do the job just as well as changing the program in the computer, they do not cost anything if you want to change the value, and you can change it as many times as you want, or go to stock all in the luxury of your own driveway, cant do that with a ABS module flash

sorry if i am coming across blunt or ignorant, I just do not understand why anybody would be against inline devices where actually there is nothing else that WILL work...?

Thanks for the quick response

Kenny

[Dusten]

Originally Posted by Mercury

Good post dusten, I appreciate your in depth description

I will say however, since the programmers do not do over 35, then isn't the only option an inline device?

other than leaving the speedo incorrect, yes.

I thought Truspeed did make them for the 08, I know speed wizard is on many 08's and no problems.

if they do, they dont list it on their site.

From my experience, I have a 2003 F250 5.4L gas engine, my computer was programmed from the factory with 31.7" tires (stock ones) i never had the computer re-programmed EVER, other then me using my tuner to change tire size (which did nothing by the way)

The engine or tranny on my truck does not use "speed" from the ABS module, and as a matter of fact (i have spent a lot of time researching this), based on my research, the only ford engine / tranny from 99 04 that does use the speed signal is the 7.3L, but when you correct the signal in the right spot (before it gets to the engine/tranny) then the engine/tranny will use the correct value.

i wasnt using the abs as an excuse, when i asked pro comp why my controller that i bought stopped at 35". They said "it sets off the abs light to go above a 35"

What about on the older trucks, when no computers were even involved... the speedometer was corrected by a speedometer gear, this method has worked well for many years, to me an inline device is doing in essence the same thing.

this is similar but, mechanical, and that is the difference.

Sure I have to agree that when you use a programmer the computer knows how many pulses per revolution it is getting, and it is the right value. But is there any functional difference between that and just sending the computer a modified value?

my issue with inline foolers is it may not be only the ecm using that signal. And changing that signal can effect the function of other things. I work with electronics daily, and i know that often times more than one feature uses a signal for calculation.

When you put larger tires on you the same pulses per revolution as before but you will travel more distance (therefore 30mph as indicated is actually more)

sorry if i am coming across blunt or ignorant, I just do not understand why anybody would be against inline devices where actually there is nothing else that WILL work...?

Thanks for the quick response

Kenny

they are the only resource for our trucks, but other than fixing the speedo, they dont change anything else. shift points, and the likes are all not effected by speed inputs. that is why i chose to leave mine alone.

And as stated before, i dont like them because i have never been a fan of changing something outputed signal. I would much prefer to change the way the signal is used at the end point

[Mercury]

Originally Posted by Dusten

other than leaving the speedo incorrect, yes.


if they do, they dont list it on their site.


i wasnt using the abs as an excuse, when i asked pro comp why my controller that i bought stopped at 35". They said "it sets off the abs light to go above a 35"


this is similar but, mechanical, and that is the difference.


my issue with inline foolers is it may not be only the ecm using that signal. And changing that signal can effect the function of other things. I work with electronics daily, and i know that often times more than one feature uses a signal for calculation.

When you put larger tires on you the same pulses per revolution as before but you will travel more distance (therefore 30mph as indicated is actually more)



they are the only resource for our trucks, but other than fixing the speedo, they dont change anything else. shift points, and the likes are all not effected by speed inputs. that is why i chose to leave mine alone.

And as stated before, i dont like them because i have never been a fan of changing something outputed signal. I would much prefer to change the way the signal is used at the end point

Everybody is entitled to their opinion...

I did choose to change mine and it has been working flawlessly, my odometer is now correct for maintenance and my speedometer is correct (helps me with the long arm of the law with speeding)

also people with over head MPG displays I beleive they use the speed signal, without a corrected signal those devices will have error.

I am having trouble over the term "fooler" why not call it a correction device?

I mean that is what it does, it corrects the pulses per revolution at the source rather then the end point. I too work with electronics daily, and use signal conditioning constantly. Garbage in = garbage out, so I would rather take in a corrected signal then to take in a wrong signal and try to make it right.

just my thought - thanks for the discussion!

have a great weekend

kenny

[Dusten]

Originally Posted by Mercury

Everybody is entitled to their opinion...

I did choose to change mine and it has been working flawlessly, my odometer is now correct for maintenance and my speedometer is correct (helps me with the long arm of the law with speeding)

also people with over head MPG displays I beleive they use the speed signal, without a corrected signal those devices will have error.

I am having trouble over the term "fooler" why not call it a correction device?

I mean that is what it does, it corrects the pulses per revolution at the source rather then the end point. I too work with electronics daily, and use signal conditioning constantly. Garbage in = garbage out, so I would rather take in a corrected signal then to take in a wrong signal and try to make it right.

just my thought - thanks for the discussion!

have a great weekend

kenny

for maintenance i know my odo is 10% off, and i use the speed display on my gps. i agree that driving with the speedo that far off is hard. I use the word fooler, because you fooling the computer into thinking it still has stock tires rather than correcting the calculations the computer does.

Does it get the job done, absolutely. Does it do the right way, not in my opinion.

[Mercury]

Originally Posted by Dusten

for maintenance i know my odo is 10% off, and i use the speed display on my gps. i agree that driving with the speedo that far off is hard. I use the word fooler, because you fooling the computer into thinking it still has stock tires rather than correcting the calculations the computer does.

Does it get the job done, absolutely. Does it do the right way, not in my opinion.

everybody can have an opinion... but if an inline device is the only way to fix it, thats better then no fix at all

kenny