4.3 V6 with lots of knock

[umbrae]

Can someone have a look at this log. Its a stock Sonoma with a ton of knock. It has new plugs, wires, distributor, air filter. Im not sure whats up with it? Where should I look? He said it was down on power and wanted me to give it a tune. I told him I didnt want to touch it untill we get this problem resolved. His MAF was really dirty. I told him to try cleaning it and call me tomorrow.

[MMGT1]

If it's a factory tune the amount of KR your seeing is not uncommon. Once you scan it again you can remove half of the KR* your seeing using your histo, and scan again. It is also said by many that the v6's have too sensitive a knock sensor.

[umbrae]

I would hate to desensitize the knock sensor if in fact its real knock. If I desensitize the sensor by 25% (for example) and I still get the same amount of knock, would that mean that its real knock?

[MMGT1]

That's why I threw that in at the end. My V6 is a 3.4 so different all around. I've covered about 35,000 km's since desensitizing mine and somewhere in the area of 50 1/4 runs.
I'd go with the method of removing half of the reported KR from your spark table and see how it looks.

[bigbrian442]

I had the same issue with my parents 2000 GMC Jimmy with the 4.3 Vortec. Since they never run anything other then 87 octane I took the 4 degree's of high octane max spark adder out. Then I tuned the knock retard out of each cell. This truck had audible spark knock at WOT. The PCM also did not have high and low octane tables. It now is allot smoother and faster, as well gets about 1 MPG better.

Russ K's method of desensitizing the knock sensors just lowers how fast the timing is pulled and then added back in. The knock sensors still see and react to any knock detected. While I left the knock sensors settings stock in the Jimmy, I have use the desensitizing on my Firebird with excellent results.