Scanner shows no knock retard during my tuning, but I have verified it is using the low octane table. It's an engineering prototype (my wife believes it's a boat), and I can hear the engine knocking at more than 35% throttle. Any suggestions on why it's not showing up?
About 1/2 way through this run, I manually set the advance to 15 degrees.
Speed density will use the low octane table for your tuning. You can smack the side of the block with a hammer to make sure the sensors work as a test.
Whats the wideband showing for part throttle AFR?
For sure the PE should be adjust for medium to heavy throttle. Get rid of that 5,500rpm and lower the pedal percent down to like 60-70% so it can command a richer fuel mixture and keep things safe.
Last edited by 5FDP; 11-01-2017 at 08:33 PM.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
Did not know that, thanks. After looking at the editor notes, I see that on MAF fail that knock learn is set to the low octane table. That explains why during my wideband tuning since MAF is failed.
However, it's indicating 0 knock retard even in closed loop mode. I have the engine set up pretty much just like it would be in the truck with both O2 sensors, a MAF, no EGR, no EVAP, no VSS, no PRNDL indication. I have had leaks in between my header and riser gasket which could sound similar to knock, but I'm thinking it's definitely knocking at higher throttle settings...say above 40%, or on quick throttle adds.
Normally, I have PE set to tip in at 40% throttle, enabled at 1,500 rpm with an enrichment rate of 3. I set to the stock settings for this tune to not spoil my wideband readings (90%TPS, 5500rpm).
The boat originally had a 350, and was propped with a 17 pitch prop. With that prop, the max rpm I could achieve was 3600. I switched to a 13 pitch which is now giving me 4600 or so on short runs, it's seems underpropped as the engine revs quickly. Given this, I would think that the loading is low enough that I could achieve a no-knock wide open throttle. The fuel is old..6 months or greater. I'm running NGK platinums, and am going to drop the heat range a couple of points to see if that reduces the knock. It could be pre-ignition, since rpms tend to drop off at high throttle settings.
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