Hi
I got a 1988 k1500 with a 99 lq4/4l80 combo.

The engine is stock but a custom intake and no more cat.

The tune is stock too

When i jump on the trottle at about 3500-4000rpm the engine start to knock (even with 94oct) up to the redline.
I did a lot of test and can't figure what the problem is.
-Checked for leak between the maf and tb
-changed the coolant sensor (its worst when the engine is cold)
-when i received

 

its more than likely a fuel related issue boss.

make sure you have a sumped tank and adequate fuel pressure.

 

Probably the stock 6.0L Power Enrichment delay. Running 14.7:1 A/F at WOT. If you ever run into any GM calibration engineers ask them WTF they were thinking when they programmed them that way.

 

Fuel pressure is ok

 

I was trying to make it run good before playing with the tune but i will try it