[mwebb]

you can not use sound to figure out / measure weather or not your ignition timing is incorrectly advanced

as you have proved
stop doing what you have already proved does not work
stop referring to what you have proved does not work as if there is any value at all connected to it

learn from your mistakes
learn from your pain

if you have a scope you can make a circuit to measure exactly when peak compression pressure happens
with out that info you are guessing , and
your ability to SWAG the correct value is less than good

you do not have a diesel engine .
you do not have a OBD2 system and if your car even has OBD1 it will not have the ability to provide the data graphed in the above post
you will need to get the data
with a hi resolution scope
like Pico 6 or similar

do you have a scope ?
if yes you can make a circuit which will generate this waveform from which you can MEASURE actual AVERAGE Peak combustion pressure
and
adjust your IGN timing so that
peak combustion pressure AVERAGE is stable around
14 degrees ATDC

if nothing else you will learn to use a scope and learn to make simple circuits
work smarter
not
harder



the blue trace is combustion chamber pressure as measured in real time with a pressure transducer threaded into spark plug hole
720 degrees between peaks as this is a 4 stroke engine
engine running BUT that cylinder does NOT fire or contribute
Green Trace is IGT ignition timing command from ECM spark begins at the end of the IGT square wave

you can measure that value with ANNOwave from AESwave
or measure the distance between peaks and divide by 720 that is the value you need to adjust

that is a common rail gasoline engine with pizeo injectors
direct injection
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see last page
http://www.herningg.com/singh/Ioniza...20analysis.pdf