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> Reducing an output frequency by two, I swear this is for my car
tazz9924
post Sep 5 2017, 03:47 PM
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Ok so, my cars (subaru engine subaru transmission) electronic speedo is double the actual vehicle speed. The Vehicle Speed Sensor produces an AC voltage and from my understanding the ecu reads the frequency of the voltage (if it reads the output voltage, correct me). How could i reduce the frequency by half so my speedo works more a less correctly?
-its not to do with the speedo im going on the number on my cobb access port which is attached to the obd 2 port
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Elliot Cannon
post Sep 5 2017, 04:36 PM
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(IMG:style_emoticons/default/biggrin.gif) https://www.amazon.com/Speedometer-Odometer...ps+speedometers
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tazz9924
post Sep 5 2017, 05:36 PM
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QUOTE(Elliot Cannon @ Sep 5 2017, 03:36 PM) *

(IMG:style_emoticons/default/biggrin.gif) https://www.amazon.com/Speedometer-Odometer...ps+speedometers

I would but i want my ecu to read tge right speed
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SirAndy
post Sep 5 2017, 05:43 PM
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QUOTE(tazz9924 @ Sep 5 2017, 02:47 PM) *
my cars (subaru engine subaru transmission) electronic speedo is double the actual vehicle speed.

So the engine and transmission and the speedo are from the same car but now the speedo reads double?
(IMG:style_emoticons/default/confused24.gif)
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DM_2000
post Sep 5 2017, 07:10 PM
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What engine computer and speedo are you using?

If stock Subaru engine computer, leave that alone as it will want to see a proper relationship between engine RPM, and road speed

If stock Subaru speedo, everything should be working fine.

I'm wondering if you are looking at KM / H vs MPH being 1 KM = 0.6 Mile
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tazz9924
post Sep 5 2017, 07:31 PM
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QUOTE(SirAndy @ Sep 5 2017, 04:43 PM) *

QUOTE(tazz9924 @ Sep 5 2017, 02:47 PM) *
my cars (subaru engine subaru transmission) electronic speedo is double the actual vehicle speed.

So the engine and transmission and the speedo are from the same car but now the speedo reads double?
(IMG:style_emoticons/default/confused24.gif)

Well kinda, its a different read end: 4.33 vs the 3.9 the wheels are also a different size. i don't know if the math works out but 60 is 30 and 130ish is about 60 to me thats about 200% increase
It could also b that the wrx uses a different vss than the legacy that outputs a different frequency or a different magnetic ring
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DM_2000
post Sep 5 2017, 08:42 PM
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Where is the VSS mounted? If it is reading from the axle flange area or a toothed wheel on the diff ring gear, actual final drive ratio is meaningless since it is reading wheel revolutions.

What size is the stock Subaru tire and what are you running now?
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IronHillRestorations
post Sep 5 2017, 08:43 PM
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Get better at dividing by 0.5 ??
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76-914
post Sep 6 2017, 08:05 AM
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QUOTE(DM_2000 @ Sep 5 2017, 07:42 PM) *

Where is the VSS mounted? If it is reading from the axle flange area or a toothed wheel on the diff ring gear, actual final drive ratio is meaningless since it is reading wheel revolutions.

What size is the stock Subaru tire and what are you running now?

It's located on the r side of the transmission. That being said; mine is connected to the ECU but I have a GPS speedo. If I disconnect the sender the car runs fine but at constant speeds i.e. the hi way, it will quit about every 8 miles until you move the accelerator pedal then it's normal again. (IMG:style_emoticons/default/beerchug.gif)
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GregAmy
post Sep 6 2017, 08:10 AM
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QUOTE(Perry Kiehl @ Sep 5 2017, 10:43 PM) *

Get better at dividing by 0.5 ??

That would double it... <---math pedant. Also hate when someone describes something smaller as, for example, "5 times smaller"...

OP, what's the speedo? Many have options for tuning by adjusting the frequency input. Barring that, there's no easy way to adjust frequency input without inserting some kind of electronic frequency adjuster in between the output and speedo. How to do that would depend on the systems you're using.
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rhodyguy
post Sep 6 2017, 09:58 AM
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You know what the speed error is. Don't sweat the small stuff at this point.
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Chris914n6
post Sep 6 2017, 09:59 AM
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timothy_nd28
post Sep 6 2017, 10:22 AM
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I think the easiest to fix your issue and for 100 dollars, get a speedohealer. It accepts all input signals, has a microprocessor to convert to the output to what you need.
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db9146
post Sep 6 2017, 10:27 AM
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Look at Tach-Adapt
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jd74914
post Sep 6 2017, 10:55 AM
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QUOTE(timothy_nd28 @ Sep 6 2017, 11:22 AM) *

I think the easiest to fix your issue and for 100 dollars, get a speedohealer. It accepts all input signals, has a microprocessor to convert to the output to what you need.


(IMG:style_emoticons/default/agree.gif)

If you want to go more "homebuild" you can build a frequency divider circuit using a D-type flip flop counter assuming the sensor is hall effect (square wave). If its a VR sensor you'd need some additional processing.
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rhodyguy
post Sep 6 2017, 11:02 AM
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What has been suggested in the 2 previous posts are the answers. Well, Kent too. (IMG:style_emoticons/default/biggrin.gif)

Kent, was that the fix for the issue that was dogging you during rt66?
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tazz9924
post Sep 6 2017, 11:04 AM
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QUOTE(jd74914 @ Sep 6 2017, 09:55 AM) *

QUOTE(timothy_nd28 @ Sep 6 2017, 11:22 AM) *

I think the easiest to fix your issue and for 100 dollars, get a speedohealer. It accepts all input signals, has a microprocessor to convert to the output to what you need.


(IMG:style_emoticons/default/agree.gif)

If you want to go more "homebuild" you can build a frequency divider circuit using a D-type flip flop counter assuming the sensor is hall effect (square wave). If its a VR sensor you'd need some additional processing.

Thats what i was thinking, thanks for all the input everyone
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DM_2000
post Sep 6 2017, 02:45 PM
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QUOTE(76-914 @ Sep 6 2017, 10:05 AM) *


It's located on the r side of the transmission. That being said; mine is connected to the ECU but I have a GPS speedo. If I disconnect the sender the car runs fine but at constant speeds i.e. the hi way, it will quit about every 8 miles until you move the accelerator pedal then it's normal again. (IMG:style_emoticons/default/beerchug.gif)




So the speedo is GPS but you want to alter the VSS that apparently isn't connected to the speedo to correct 2X speed? That won't work.

Do you have a set up sheet for the GPS speedo?
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tazz9924
post Sep 6 2017, 06:50 PM
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QUOTE(DM_2000 @ Sep 6 2017, 01:45 PM) *

QUOTE(76-914 @ Sep 6 2017, 10:05 AM) *


It's located on the r side of the transmission. That being said; mine is connected to the ECU but I have a GPS speedo. If I disconnect the sender the car runs fine but at constant speeds i.e. the hi way, it will quit about every 8 miles until you move the accelerator pedal then it's normal again. (IMG:style_emoticons/default/beerchug.gif)




So the speedo is GPS but you want to alter the VSS that apparently isn't connected to the speedo to correct 2X speed? That won't work.

Do you have a set up sheet for the GPS speedo?

Idk about him but i have no speedo gauge rn (therefor no gps). I am reading my vehicle speed off my cobb access port which is attached to the obd2 port which tells me the ecu thinks the vehicle speed is twice what it is
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Chris914n6
post Sep 6 2017, 11:35 PM
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You need the suby speedo to convert the vss signal to what the ecu needs to see.
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