Official MPGuino preassembled now available

[evgrready]

My GTI does not have cruise control, so its all analog.
Putting a analog VSS(Permanent Magnet Style) sensor like the bicycle was an option but I wanted to know if there are a Hall effect sensor that you could put in line the speedo. I remember I have seen it on like an Jeep, where it has a shaft that connects to your speedo cable, and has two wires coming out for a electric signal. It would not be a digital signal but its would be a frequency one.
Would the MPguino would pick up the signal like that? or it has to be a digital one (like a hall effect)
Thanks for the reply. I cant wait to get my hands on mine.

[Eddles]

When I installed aftermarket cruise control on my car, the manual had information on how to solve the problem of getting speed data to the cruise control on cars with a mechanical speedometer, or no electronic speed pick-up[1]. It said that there was an optional package that can be brought and installed, and then wired up to the cruise control. I was lucky enough that my car had an electronic speedometer, so I don't know much about this.

Maybe it's worth looking for something like this if it's cheap? If you want, I can have a peek in the manual and find out more about this? Of course, I don't know if this will actually work with the MPGuino so it's just my 2 cents.

[1]Like one car I used to have that was built in 1990, had a strange electronic/mechanical hybrid piggy-backed on top of each other - the electronic pick up went to the computer, while the mechanical one went to the speedometer. Double check your car don't have this?

[GlenH100]

Back in the '70s, Heathkit sold a cruise control package that was basically Dana (now Rostra) hardware. The VSS sensor arrangement was two or four (memory is fuzzy) magnets taped to the driveshaft with a pickup coil placed in close proximity to them. OEM systems based on the same design usually had a speed sensor in the middle of the speedometer cable. IIRC, these devices worked as small generators and produced a voltage that was proportional to vehicle speed.

Today, one could use a Hall effect sensor in much the same way to generate pulses.

--Glen

[dcb]

hall/magnet is better since it will work at slow speeds. the coil/magnet needs a certain amount of rpm before it will make a strong enough signal.

[racprops]

I have installed about 6 of these types on many cars and trucks I have owned, and it is only used as signal generator, not a voltage generator, and would work down to around 30 MPH and up to 80 + MPH normally.

A lot of aftermarket cruse controls came with them as did the old mileage computer.

Most of the time it was only two magnets wired to the shaft.
I read somewhere how to make a set by taking the coil from a 12 volt relay and using it to pick up the magnets when you got a unit with no magnets or pick up and it was left on the car.

Rich

[ECONORAM]

Donation sent. I have found the VSS values for my Dodge RAM, or at least I think so. I just need to find the usec/gal for my truck. Yes, my truck is CAN bus, but I already have a Superchips 3815 that I use to monitor most gauge readings, including ignition advance and fuel trims (and I can data log with it) so I really need something that does not use the OBD plug...

[ECONORAM]

Well, I gooned my install a bit. I used the VSS ground (DG/VT) instead of the VSS output wire (DG/BR). I drove with it like this for about 300 miles. Did I fry anything? I have since found the correct wire, but have not reconnected. I will say the fuel consumption portion worked great. It was neat to see the gallons tick by (until I realized how many that really was...).

[dcb]

if that was the only "oops" then it should be fine. Sounds like you have an initial correction factor for fuel sorted out.

Do you know if it is a 12v signal on the vss?

[ECONORAM]

Thanks dcb,
Yes, I think I got a pretty good fix on the usec/gallon. I am using 0114596879.1. That may not be dead on, as I had driven about a mile before I was able to recalibrate, but it is close.
I had assumed it was 12v, but learned tonight from a site that the vss signal gets a 5v feed. I tried the vss input wire tonight, but it only seems to get a signal up to about 5 mph, then nothing. I was thinking about finding the feed off the tranny before I read that thread. Now I'm at a loss. Any ideas? Thanks, Dave
edit--I forgot to ask, how could I measure this while driving?

[nickdigger]

for a 5v vss, try swapping the 100k resistor with a smaller one, like 30k.