I have quite a few datalogs showing evidence that a 10:1 AFR or less will cause knock. Keeping the same SA I can lean out the mixture for the best "feel" and no knock which is around 10.6:1 on my engine.

Has anyone else seen this?

 

It could just be misfiring. Your getting close to the rich burn limit there.

 

If the AFR you are seeing is reported via a WB, it may be that there is too much timing. I would reduce the timing several degrees and see what the AFR does. You shouldn't need to run that rich with moderate boost levels.

Also double check the WB setup in the preferences menu. And if it is a programmable output WB double check the output vs. AFR setup.

RBob.

 

I too have come across this (where richening the mixture caused detonation but leaning removed it). But I was at the "threshold" where just 1/4* more of spark advance and I had major detonation - like Bob was mentioning above.

But, when I backed off the spark a little more, then everything returned to "normal" - just as Bob is suggesting.

If you too are at the "threshold" of spark advance which will induce detonation then you and I have something in common. And it does raise a question "why does this happenning", as it is almost counter-intuitive...since richening the mixture is suppose to be a "fix" for detonation when you are at the "threshold" for detonation caused by too much spark advance.

Maybe it has something to do with the too rich mixture leaving "hot particles" in the combustion chamber that are not evacuated in the exhaust cycle.

 

I'll throw this out there for the sake of detail...

When I had the engine under a QJet and HEI, I was running 26° advance under 5 psi of boost.

If I reduce the timing only in those areas the engine is very sluggish. Maybe I should try reducing SA and fuel?

The AFR reading is from a ZT-2. I have the Zietronix WB selected in the WUD preferences. I'm using the white wire (wideband analog output) from the controller to the EBL.

 

I've run into a situation like this before, too. My pinging seemed to go away or atleast lessen when I pulled some fuel out.