Tire / Axle out of acceptable range?
#1
12-09-2002, 10:02 AM
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Tire / Axle out of acceptable range?
Plugged in the Microtuner to read my DTC's finally and got this message. I have 33's on and have set my ECU at 30.25" for accurate speedo reading. They are probably actually 30.5" or so though. Is this DTC simply because I'm using a non-stock tire size or? How does it know it's out of range? Thanks!!!
-AR
-AR
#2
12-09-2002, 08:55 PM
Former Sponsor
Hi Jackal,
That could well be what your code is about, there is a conflict between VSS data & other data streams used to confirm the VSS data & it reports a code. The PCM & it's systems have the ability to determine when the Speedo is off, and that can indeed set a code.
Make sure to actually measure your tires from the pavement ot the top of the tire as installed on the vehicle, and plug *that* tire height in, not what the sidewall says or what the manufacturer says the height should be, always measure it, as most tires are shorter than claimed, only partly due to installed compression (from vehicle weight). There is a little bit of "tire growth" at higher speeds, but not enough to make a big difference, so just measure the tire and then plug the actual height in, & you're set.
As far as "how" the PCM can tell when the speedo is off, the PCM knows the VSS is off basically by comparing things like engine rpms, output shaft speed & other data streams to what is reported via the VSS, in essence.
That could well be what your code is about, there is a conflict between VSS data & other data streams used to confirm the VSS data & it reports a code. The PCM & it's systems have the ability to determine when the Speedo is off, and that can indeed set a code.
Make sure to actually measure your tires from the pavement ot the top of the tire as installed on the vehicle, and plug *that* tire height in, not what the sidewall says or what the manufacturer says the height should be, always measure it, as most tires are shorter than claimed, only partly due to installed compression (from vehicle weight). There is a little bit of "tire growth" at higher speeds, but not enough to make a big difference, so just measure the tire and then plug the actual height in, & you're set.
As far as "how" the PCM can tell when the speedo is off, the PCM knows the VSS is off basically by comparing things like engine rpms, output shaft speed & other data streams to what is reported via the VSS, in essence.
#3
12-10-2002, 08:57 AM
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Interesting, thanks man...but does it "hurt" anything since I have a 5-speed? My speedo is consistant with two other cars I had pace me, maybe just a mile or two over at 50 mph. Also, when I make a tire size change like that, does the computer have to re-learn my driving habits all over again?
-AR
-AR
Last edited by Jackal; 12-10-2002 at 12:28 PM.
#4
12-10-2002, 12:22 PM
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Well, I just scanned again, after clearing and I still get the same code. I measured again. My height at rest (on the ground) is 31.125". My top side rim to sidewall distance is 6.75", and my bottom side is 5.875", so this leads me to believe my tires are 32" tall off the ground and I have 7/8 th. of an inch of "squish" all around the tire. This makes my total "functional" height 30.25", which is what I have it set to. If I set the value to 31", my speedo is off by about 4 mph. at 50 mph. Just out of curiousity, what is the stock value of a 265/70R17?
Has anyone else gotten this code?
UPDATE!!! I just found this post. Looks like I'm not the only one. "trueblue" says it has something to do with the "VID Block"?
http://www.fordtruckworld.com/forums....asp?id=105656
-AR
Has anyone else gotten this code?
UPDATE!!! I just found this post. Looks like I'm not the only one. "trueblue" says it has something to do with the "VID Block"?
http://www.fordtruckworld.com/forums....asp?id=105656
-AR
Last edited by Jackal; 12-10-2002 at 12:53 PM.
#6
12-11-2002, 08:12 PM
Former Sponsor
Hi Jackal,
You're not getting a check engine light from this, all you're getting is a stored code *if* you scan, which hurts nothing, and is nothing to worry about, it happens even in stock trim sometimes.
I have to point out that Tech Support cannot be done here, that is clearly prohibited by the policies of F-150 Online, so I will go over a little bit of this with you heer just very briefly right now, and then if you want to know more about this you'll need to contact the manufacturer at the number listed in your Micro Tuner's documentation.
To get you some brief info (and I'll only make this one post on this topic here so as not to break more rules), yes, there are sometimes limitations as to how many times you can do that in certain PCM codes (usually at least 6) before the PCM needs to be cleared for that, which is more than sufficient. Once is all it takes if this is done correctly, which means manually measuring your tire height and plugging that in and then leave it alone, that's it, it's done. Period.
However, that is very rarely any kind of actual problem, sometimes you are still going to get a code as you are not going to have 100% agreement between VSS and all the various data streams the PCM uses to confirm VSS data, like engine rpms, output shaft speed, wheel speed, etc., or even with things like GPS or a radar gun, and that happens sometimes even in *stock* trim.
Many of these speedometers (the vast majority) are already reading a bit slow or a bit faster than actual speed right from the factory, they are *never* dead-nuts on, and it cracks me up when I hear someone say "oh, I tested it with a radar gun and it was perfect at every speed right on up to 80 MPH!" Malarky, speedo's aren't that accurate, effective tire growth alone assures that. There was a relatively decent article in C&D some time back about the accuracy rates in general of speedometers in modern vehicles, as well as other similar articles in various publications (consumer and trade) over the past few years, and a number of the vehicles tested (which included Ford trucks) had as much as a 2%-3%+ error rate in the speedometer right from the factory!
One thing you'll want to remember about this in general is that your tire size is *NOT* always static. You have maximum compression when stationary (which makes the tire "shorter"), and as road speed increases you have less compression and more (in effect) tire "growth," thus affecting the speedometer, quite naturally. The speedometer's accuracy is also affected by tire pressure as well, so as we can quickly see, there is no such thing as a truly "perfect" speedometer calibration, even from the factory, due to any number of factors, especially obvious factors such as variations in tire size throughout the range of operating conditions including speed, temperature and tire pressure at a bare minumum.
For any more info you can contact the manufacturer on this, they're gogin to have more info on this than anyone else obviously. And of course as always, you can give us a call and I'll be happy to go over this with you. We just can't do that here my friend, & thanks very much for your understanding on the policies of F-150 Online, it's greatly appreciated.
All the best,
You're not getting a check engine light from this, all you're getting is a stored code *if* you scan, which hurts nothing, and is nothing to worry about, it happens even in stock trim sometimes.
I have to point out that Tech Support cannot be done here, that is clearly prohibited by the policies of F-150 Online, so I will go over a little bit of this with you heer just very briefly right now, and then if you want to know more about this you'll need to contact the manufacturer at the number listed in your Micro Tuner's documentation.
To get you some brief info (and I'll only make this one post on this topic here so as not to break more rules), yes, there are sometimes limitations as to how many times you can do that in certain PCM codes (usually at least 6) before the PCM needs to be cleared for that, which is more than sufficient. Once is all it takes if this is done correctly, which means manually measuring your tire height and plugging that in and then leave it alone, that's it, it's done. Period.
However, that is very rarely any kind of actual problem, sometimes you are still going to get a code as you are not going to have 100% agreement between VSS and all the various data streams the PCM uses to confirm VSS data, like engine rpms, output shaft speed, wheel speed, etc., or even with things like GPS or a radar gun, and that happens sometimes even in *stock* trim.
Many of these speedometers (the vast majority) are already reading a bit slow or a bit faster than actual speed right from the factory, they are *never* dead-nuts on, and it cracks me up when I hear someone say "oh, I tested it with a radar gun and it was perfect at every speed right on up to 80 MPH!" Malarky, speedo's aren't that accurate, effective tire growth alone assures that. There was a relatively decent article in C&D some time back about the accuracy rates in general of speedometers in modern vehicles, as well as other similar articles in various publications (consumer and trade) over the past few years, and a number of the vehicles tested (which included Ford trucks) had as much as a 2%-3%+ error rate in the speedometer right from the factory!
One thing you'll want to remember about this in general is that your tire size is *NOT* always static. You have maximum compression when stationary (which makes the tire "shorter"), and as road speed increases you have less compression and more (in effect) tire "growth," thus affecting the speedometer, quite naturally. The speedometer's accuracy is also affected by tire pressure as well, so as we can quickly see, there is no such thing as a truly "perfect" speedometer calibration, even from the factory, due to any number of factors, especially obvious factors such as variations in tire size throughout the range of operating conditions including speed, temperature and tire pressure at a bare minumum.
For any more info you can contact the manufacturer on this, they're gogin to have more info on this than anyone else obviously. And of course as always, you can give us a call and I'll be happy to go over this with you. We just can't do that here my friend, & thanks very much for your understanding on the policies of F-150 Online, it's greatly appreciated.
All the best,