I've got a customer that I'm helping on a 6.0L LQ9/4L80E swap in a 1982 Chevy K10 truck. We're running the 6.0L LQ9, 4WD 4L80E (2007), and NP208 transfer case that was in the truck when he picked it up. Since the truck uses a speedo cable and we're keeping stock gauges, we bought a Dakota Digital 8K VSS pulse generator (http://www.dakotadigital.com/index.c...109/prd109.htm). Does anyone have any idea how to tune for this? I had HPTuners do a segment swap for the 4L80E if that makes any difference.
I found this thread: http://www.hptuners.com/forum/showth...ital-pulse-gen and followed the instructions from mecanicman. Basically, changed General VSS pulses per Rev trans value from 40 to 8 and used 20% of the value that was in General VSS pulses per mile and Final Drive Gear Ratio Trans Revolutions per Mile.
Doing that, the PCM seems to read the VSS, although its about 30% too low (expected as the tune I'm using has 3.73 gears and 30" tire whereas the truck with the swap has 4.88 gears and 33" tires). I haven't gone thru and corrected for that error yet because I tried to use Blue Cats spreadsheets and program that he just released, but the results from that program are VASTLY different on the General VSS pulses per mile and Final Drive Gear Ratio Trans Revolutions per Mile. The VSS doesn't even read if I use the values from his program/spreadsheets. Does anyone know the actual way to tune for this? Should I continue with using the 20% of the stock values and correct from there or is there some other way to tune for this VSS.
We did correct the drive and driven gears (15T and 45T if I remember right) on the speedo cable so that the speedometer is reading correctly in the truck. We are reading 55MPH with an actual speed of about 52~53MPH.