VSS location - GM 3.1 MFI

[Nevyn]

Hi all. I have my MPGuino "installed" in my car, to a degree. I have a line coming straight from the injector in the engine bay to the MPGuino through the door frame as I'm still working out how I want to enclose it.

The VSS line in my car, 93 Chevy Lumina Euro with the 3.1L (pre-3100) engine does not lend itself well to pulling the VSS in the same way. I'd come straight from the ECU, but it's hidden under/behind the radiator coolant tank on the passenger side of the vehicle.

Does anyone know where it comes into the car at to go to the speedo, and what color it is? Any help would be greatly beneficial.

[americasfuture2k]

if you can locate your ECM and the service number on it, i may be able to help. that is if it is the 1227730. you have DIS right?

[Nevyn]

The ECM is underneath the engine relay bank, behind the radiator coolant tank. I'd have to remove both of those items to find the number. I do know the following, that I found from Rostra:

93 CHEVROLET LUMINA CAR 3.1,3.4L

VSS Wire: Location 17 White Connector, Position B-8
VSS Wire Color: Dark Green
VSS Pulse: 4000

My Haynes manual also shows that the VSS out from the ECU/ECM is "DK GRN." I don't know if it stays that color when it comes into the car from the engine bay or not.

It's looking like the only way to find it inside the car is to take apart the dash and pull the cluster. Either that or pull the rad tank and tap at the ECU.

[wagonman76]

It would be easiest and most surefire to just pull the instrument cluster and tap into it there. If it goes together like most GMs of that era, you will be able to trace the circuit from the back of the speedo/odo to whatever wire the connector plugs into. Whatever wire is dedicated to it is what you want, there should be 2 other wires (12v ign and ground) that go to multiple places on the circuit so you don't want those.

It is most likely dark green. It was dark green on my 92 Trans Sport van.

Also, it will probably turn out to be more like 8000 PPM. No idea why it is, unless the mpguino counts a pulse twice as it energizes and de-energizes. Both my 6000 wagon and Trans Sport van are listed as 4000 PPM in the service manuals, but actually are around 8000 according to the mpguino.

Your microseconds/gallon will probably be around 251500000 as well. Thats what both my 2.8 and 3.1 MPFI engines work out to be on average.

[Nevyn]

I used the nice convenient Excel sheet and did the conversion for the pulse width. I plugged in both the lb/hr and the cc/min info, and averaged the two results for a resulting 236863230. That part seems pretty okay, but it's rebooted/locked up on me and I lost my tank data to compare it to. I know the PPM is 4000, and the guino is designed to work with a doubled PPM number. I'm not looking forward to pulling the whole dash apart just to get the cluster out, but that's probably what I'll need to do.


Yuck.