Official MPGuino preassembled now available

[nickdigger]

To measure vss voltage on my mpguino, i set my meter to 20vdc, stuck one probe on electrical ground (what you call "12v neg"??), then touched the other probe to the 'inner' side of the resistor. This would be the same as touching the "analog pin 0" contact on the board, where the vss signal goes in. This is where you should see it bounce from 0 to 3v while the wheels spin.

If you're not getting a reading from your VSS wire, with or without the mpguino attached, you must not have the right wire. Your key must be turned to "ignition on" to get any vss signal, but engine probably doesnt need to be running.

Dont know what to tell you about troubleshooting for damage, though. I'm probably fortunate myself, that i havent fried something on mine

[ECONORAM]

Well, thank God I paid attention and wired this into a fused power source. I checked today and I had blown the fuse for my power plug. So, I replaced the fuse and the MPGuino is still alive. Just gotta figure out where to get a good speed signal. My wiring diagrams are not helping much. How hard is it to get and wire up a hall sensor on the driveshaft?

[racprops]

I too am working on the VSS, on a 1993 Chevy Van. FYI my manual calls for around 2000 pulses per mile.

I have the factory Service manuals and located three VSS pulses, the raw incoming from the tranny, and two buffered outputs one to the speedo and one to the EMC.

I tried the one for the speedo but it seems to count up even standing still.

Should I use the raw incoming one, or try the output from the VSS buffer to the ECM?

Rich

[dcb]

If you could post a schematic that would help.

[racprops]

Originally Posted by dcb

If you could post a schematic that would help.

IS that for me??

There are three VSS outputs in my van: one from the transmission that goes into the VSS Buffer and the two out from the VSS Buffer, one to the speedometer and one to the ECM.

I am running on the speedometer's and it seems to have some steady output that seems to make the MPGunio count miles ever standing still.

Can I use the raw output from the transmission? OR should I use the one to the ECM?

Rich

[dcb]

I don't know vehicle specifics usually, you should use the one that works

I doubt the raw transmission output will work as-is, you need a 0-12 volt signal.

If you (or anyone with specific electrical questions) has a link or uploadable schematic that is germane to the question then that would help.

When I hear "count up even standing still" then it is time for a reality check, that isn't a vss signal as I know them.

[racprops]

Originally Posted by dcb

I don't know vehicle specifics usually, you should use the one that works

I doubt the raw transmission output will work as-is, you need a 0-12 volt signal.

If you (or anyone with specific electrical questions) has a link or uploadable schematic that is germane to the question then that would help.

When I hear "count up even standing still" then it is time for a reality check, that isn't a vss signal as I know them.

Thanks I will then try the only other output, the one for the ECM.

The schematic shows three boxes, one the Tranmission VSS sensor, one is the VSS Buffer, and last the ECM.

It is dirt smiple: 6 wires: 2 are B+ and B- GND.

Two are shown hooked to the Transmission's VSS sensor.

The last two are shown as: One to the ECM.

The other goes to the electronic speedometer.

I will recheck the readouts, and see which is not responding correctly.

Rich

[racprops]

OK Here are the readouts.

Unit is powered full time. Key and engine is off:
Instant tank:
IM000.00 SO000.00
IM000.00 SO00.00

Instant/Current:
IM000.00 SO00.00
CM999999 DO00.00

Custom:
MG00.00 SO00.00
GH000.00 C999999

CPU Monitor
C%643.33 TO30.35 THIS IS COUNTING UP
FREE MEM: 247.00

ECG/IDLE
CE00.00 GO00.00
TE000.00 GO00.12

TANK
MH04---THIS IS COUNTING DOWN
MG021.99
MI025.95 GA001.18

CURRENT
MH000.00 MG999999
MI000.00 GA000.00

BIG TANK
22MPG
BIG CURRENT
999
BIG INSTANT
000


Note the van normally gets around 16MPG highway..

And the two counts are running standing still all by themselfs and key and motor are off.

Is this normal?

I don't remember seeing this on my other unit in my 2000 Ford.

Rich

[dcb]

Ok, gotcha, thought you were looking at distance reading or something.

CPU Monotor T is the "Tank Time" in seconds since it has last been reset, that is BAU.

Time is also a variable in the tank MPH figure, which explains why the mph reading is going down with the car sitting there.

What is curious is that it says you have driven 25.95 miles on this tank, and you are still sorting out the vss.

[dcb]

Quick checks to see if the connections look right.

on the custom screen:
start the engine, you should see the gh (Gallons per hour) reading go up, more gas pedal should give larger gh . If so the injector connection is probably ok.

Drive, the S number should be proportional to vehicle speed, if so then your vss connection is probably working.