OTC 2000, and '86 GN


When I connect to my '86 gn with an OTC 2000, and select model year 1986, I do not get any readings for Knock or Knock Retard. However I today I tried selecting model year 1987, and I get both. Are they valid readings?
My knock retard shows as high as 13- 15 half way through 2nd gear not even at WOT.
And I noticed yesterday that when I got on it I could hear it knocking toward the end of 2nd gear and I let off right away.
Trouble Code 34 just came on as I came in the driveway, MAF sensor?

ANy of this stuff linked together????
What years are listed on the software cartridge? I had the 89 software. I don't know the difference. I am sure it will offer different functions according to the years covered.
I believe '81 thru '87. That is my guess as well. The code in the cartridge will read certain information for certain years regardless of what the ECM data stream is sending.