OBD1 S50 is VSS required?

[aaron.j]

Finishing up my S50 OBD1 swap on the e21. The e21 doesn't have an electronic VSS. Ive read conflicting info on whether I need it or not to allow the engine to have full rpm capability. Is this an OBD2 only thing or what?

[328ijunkie]

I had to add in an E30 speedo and E30 trigger wheel/sensor to the last E21 swap i did.

[aaron.j]

did you run the sensor directly to the DME? any info on how you mounted it

[aaron.j]

Have you ever scoped one of these signals? wondering what it looks like going into the dme. I could possibly tie it into another sensor to trick it. I remember reading that somewhere..

[328ijunkie]

its a weird square wave if i recall correctly. My Fluke 88 only gives me a reading in HZ sadly so i cant see what it looks like exactly.

[aaron.j]

Well, damn. Did take apart and use a vdo cluster or motometer? About to purchase some shit to get this thing done.

[328ijunkie]

VDO. I can kit you something. Email me.

[aaron.j]

Sent

[aaron.j]

Can anybody confirm the input into the dme (speedo output after being processed) is 7784 pulse per mile and it a 0-5v square wave?

[328ijunkie]

square wave for sure. I can pulse one out if you want.

[aaron.j]

If you have time. Feel like im asking a lot from one person.

[aaron.j]

Bueller?