Got a handheld tuner (I know I Know) and it's showing knock on a stock tune but it's weird.

1st gear 0 to whatever no knock at all and about 17 degrees of timing, I never get any knock what so ever in first, WOT, 50%, 25%, anything.

2nd gear, 3500 RPM+ WOT spark knock at 17 to 18 degress of timing. Sometimes it'll go to 3* of KR then even out.

4th Gear, converter locked, anything more then 50% engine load (even at 1600 RPM and 65 MPH) and I've got knock, I can roll on to pass someone and i'm getting knock at 30% throttle. Running 87/89 Octane, Mobile fuel. We have a 10,000 gallon tank at work and we go thru that in about 2 weeks, the fuel seems good as no one else is having problems, even scanned a 08 GMC w/ 5.3.

Any help??????

 

You will have KR on a stock tune, I have seen as high as 7 degrees KR on some stock tunes.