MPGuino Speed sensor

[95CamaroV6]

My car has a very unreliable cable speedometer that reads 3 mph fast as well, so I dont want to hook my mpguino up to that. I was wondering if a speed sensor from the abs system would be compatible with the mpguino or if I need to try something else?

[AndrzejM]

You can try hall sensor or contactron and a magnet attached to driveshaft, or maybe two if you want to have more pulses per mile. You can also use a set from bicycle speed/odometer.

[95CamaroV6]

if the sensor was on the driveshaft wouldn't that basically correlate to the injector pulses/rpms that are already accounted for? I would want a place where absolute speed could be measured basically

[95CamaroV6]

would a driveshaft reading work fine with the mpguino? Sorry I'm a n00b with sensors and whatnot

[95CamaroV6]

Would the ABS sensor be workable?

[AndrzejM]

Camaro, you need two input signals for MPGuino one is the vehicle speed sensor and second are pulses from a fuel injector. You've asked if you can use ABS sensor but I think it's not the best idea, because of the pulses count per revolution. MPGuino can lose some pulses and then the output will be not in correlation to reality. So the best way will be to glue one, two, maybe four magnets to the main shaft of your Camaro and put there contactron or a hall sensor. And you have constant number of pulses per mile, and that's the idea of VSS.
Second wire you have to connect to one of the injectors and then you have amount of fuel, and rpm signal for MPGuino.

That's all you need, to make your MPGuino working.

And a simple diagram for you:

1. +12V
2. VSS signal for MPGuino
3. 0V
4. Resistor ~10kohm
5. Contactron
6. Magnet
7. Main shaft
8. Diff

[95CamaroV6]

Okay thank you, and does it matter how many pulses the guino recieves? (or how many magnets I put on the driveshaft)

[msc]

Do you have an electronic speed signal out of the speedo? Often there will be a distance pulse stream supplied to the ECU even when there is a cable drive for the speedo. If you have such a signal available I would use that instead of an ABS signal. En error in the mechanical speedo would not likely show up in the electronic signal.

The ABS sensors are generally a variable reluctance sensor where the signal level drops off at lower speeds. It is possible to use such a signal but it takes additional circuitry and even then some distance pulses can be lost at very low speeds.

Mike

[95CamaroV6]

I asked about the ABS sensors because my electronic VSS is messed up (the reason why I have an aftermarket cable speedo). I'm just confused about how to have the hall effect sensor give the guino appropriate pulses (like how many magnets to put on the DS. If its too much trouble I might just use the ABS sensor if it will work above 20 mph..

[msc]

What do you know about the vehicle VSS signal problem? I would think the real solution is to fix the car so the built in speedo works. I understand that may mean something like a new cluster and more cost then the car is worth. It's possible the VSS signal is still good even if the cluster is dead so it's worth investigating.

See this thread for discussion of interfacing to the type sensor used for ABS.
http://ecomodder.com/forum/showthrea...ed-16518.html?

Mike