MPH calibration, quick question

Pronto

Believe nothing you hear and half of what you see.
Joined
Dec 9, 2002
My setting from Cal are 1800 ppm, 730 mph calibration and 100 aux ppm. My mph is off by about 8 or so mph high. Should I adjust mph calibration to a higher # or lower and about how much? I tried adjusting it a few numbers lower and saw no change in the mph at 30 and 60. Just looking to see if I can get it closer without fiddling with it for hours. I know you can pull up the gauge panel and do adjustments on the fly but at the moment can't do that safely alone. BTW, my speedo is perfect as per my gps speedometer app. Thanks!
 
Curious what you're told. I put a Dakota digital in mine and it's all over the place. Need to figure it out but just haven't had time to take it out and play with just the calibration

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My numbers are steady but off. I know it's not the end of world but it's annoying to me.
 
My setting from Cal are 1800 ppm, 730 mph calibration and 100 aux ppm. My mph is off by about 8 or so mph high. Should I adjust mph calibration to a higher # or lower and about how much? I tried adjusting it a few numbers lower and saw no change in the mph at 30 and 60. Just looking to see if I can get it closer without fiddling with it for hours. I know you can pull up the gauge panel and do adjustments on the fly but at the moment can't do that safely alone. BTW, my speedo is perfect as per my gps speedometer app. Thanks!
I think the PPM should be 2000
 
My numbers are steady but off. I know it's not the end of world but it's annoying to me.
Funny how some of these things can annoy the snot out of ya. Most of my TR buddies could care less about MPH or other non-performance related insignificant matters.

I've may have the same disease as you.
 
So I scoured TB for what people have run for driveshaft ppr, mph calibration and aux. The numbers are all over the place! These are what I could find that people said worked for them. Not all said their gear ratio and tire size so these numbers may have worked for them because of their set up. Some start with 600, 750, 1500 and 1800 (Cal's number) for ppr and 1482, 1482, 775, 995 (100 aux), and 730 100 aux (Cal's number). I did not experiment with changing the ppr to a lower number and calibration to a higher number. The ratios seem to near each other so I imagine it's the ratio that's works not what numbers go where? It also seems the stock vss signal is a vague and variable number. From what people had posted it may be different on each car? Maybe because of that and gear/tire combo explain why the numbers that work are wide spread? Getting way out of my knowledge on that. At any rate, an experienced friend suggested to start with the 1800 and try around 650 and 100. Right out of garage the speedo and Edash were in sync! Great to see I accomplished (with help!) my first "adjustment" with FAST XFI! In my earlier trys to adjust, I only went as far as 715 and barely noticed a difference. From the new numbers, it took 80 "points" to go 8 mph. I was on the right track, just didn't keep going lower. So to wrap up this long winded post, if you have 3.42 gears and 275/60 tires and want to adjust your mph calibration, expect to change about 10 numbers to 1 mph. Your results may vary, lol.
 
I wish I could help. I have XFI and am using their driveshaft speed sensor. (only 2 pulses per revolution) Also a 28" tall tire. 3.42 stock ratio, And I had to change the speedo gears in the TH400 so that my speedometer read close to accurate as well.

In the end.......The number I calculated using the XFI formula is 1591. This reads about 6 MPH lower on a data log than the race track's recorded time of 146 MPH. When I'm under 85 MPH, the laptop shows it's a little higher than my speedo.

But at cruise the differences are minimal. Testing by driving along side my girlfriend in the daily driver.

Just like you said........"results may vary"
 
Your results reflect alot of what I read. The actual speed and XFI speed may sync up at points but may be off at other points. That seems to be stumbling block. You even have eliminated the vss vodoo which in theory should make your calibration more accurate.
 
Your results reflect alot of what I read. The actual speed and XFI speed may sync up at points but may be off at other points. That seems to be stumbling block. You even have eliminated the vss vodoo which in theory should make your calibration more accurate.
Well, I believe I have gone as far as I want to.

The next step would be to get one of those new GPS speedo thingies. But truthfully, what's on the data log would be most important to me. I often data log on the street and a time slip is simply not available.

Unless it's in the form of a speeding ticket. In which case, I don't want any part of it.
 
Im curious about this as well. I just posted asking pretty much the same question and then found this post. Im guessing you are also running 28" tire and stock gear ratio? Pronto what numbers did you end up with ?
 
1800 650 and 100. The mph calibration doesn't seem linear. I only needed about 8 mph but had to go a whole 80 points south to get there.
 
yea it definitely does not seem linear which is kinda odd, that's what I was getting confused about. if you don't have the correct ppm then the mph calculation that fast gives doesn't mean anything. ill give your numbers a shot and see what happens. thanks
 
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