XGauge coding: My data is wacky

[theholycow]

I'm trying to create XGauge codes for my GM VPW system (2002 GM 5.3 engine, 4l60e transmission) on my ScanGauge II, but I'm having trouble interpreting my data. When I try my codes as CMNDS, I look at the response, pull out the data, and put that through a Hex-->Decimal converter; sometimes what I get could make sense but while driving it doesn't follow driving conditions properly, other times what I get makes no sense.

Everything I read implies that the last two digits of the response are to be discarded. (Edit: The last two digits are a one-byte CRC.) I've found a few lists of PIDs that I think are correct beacuse every PID they share matches.

I sat idling and entering CMNDS to see which PIDs work and which don't, and to gather sample data. Here's a few of them:

1192 Desired Idle Speed. Response is 2cf4. 2c = 44 (presumably to be multiplied x10). Actual idle tends to be well over 500, so either "Desired Idle Speed" doesn't mean what it sounds like or the truck never gets near the desired speed.

1141 Ignition Voltage. Response is 8d0b. 8d = 141. Is "Ignition voltage" the voltage at the ignition wire in the dash (which would make this data '14.1', which would make sense) or is it the voltage in the spark plug wires (which I guess could mean it was 14,100 volts; I thought spark plugs run a lot higher voltage than that).

1212 Rich/Lean to Lean/Rich Ratio Sensor 1. Response is 188f. 18=24. What could this sensor mean?

1212C: Average O2 Bias Voltage. Response is d39a. D3=211. Another one that I'm not entirely sure what it means.

1172: IAC. Response is 003d69. 003d=61. This could be percentage of IAC opening, not really sure.

The ones that I really want the most:

125a and 125b: Fuel Injector Pulse Width, banks 1 and 2. Responses include 00bff3 (00bf=191), 00c465 (ooc4=196), 00c5f7 (c5=197). Does that sound right? What units might it be? How do I convert pulse width to duty cycle so I can know if this is accurate (compared to my direct measurement of duty cycle)?

1970: TCC PWM Duty Cycle. Response is 002d (00=0) at idle, but is all over the place while driving and rarely seems to make sense.

1991: TCC Slip Speed. Response is 114c55 (114c=4428) at idle. It should be zero or very low at idle, right? This one is also wacky when driving.

I want to know when my TCC is locked, and either of those last two should tell me...if I can get them working right.