I was just out tuning my cavy, playing with the timing advance...
i got to a point where the KR spikes suddenly, and there is a VERY FAINT noise like the rattling of a hairbrush in a plastic cupholder....
nothing like the "marbles in a coffee can" that i have had it explained as before....
this was very soft and gentle... like plastic on plastic... but i rather high frequncy... kinda like the general noice of marbles in a coffee can... but more like plastic BB's in a paper cup.
just curious if that is just what "knock" sounds like on the LD9...
can anyone who has heard this before tell me if this is what they heard too.
i have heard knock on harley davidsons, and big V-8's... but this was some of the most wussy sounding knock ever. i seriously thought i had something rattling in my cup holder...
Did it sound like popcorn popping? What was your timing advance at on this run, can you post a datalog file for us to look at?
FU Tuning
hmmm... maybe popcorn in those old fashion tinfoil and cardboard stovetop poppers... how it would sound from across the room.... how it is kinda muffled and tinny and distant... as if you were sitting on the couch and would hear at and ask "hey is someone making popcorn in there?.... not like modern microwave or hot air poppers where you can actually hear poppoppop.
Imagine more of the sound of a plastic bristle hair brush on the edge of a wooden table... lots of lil kackels... but no real poping or knocking....
on my harley knocking sounds like someone rapidly smacking a big hunk of aluminum with a small hammer.... kind of a DUNK DUNK sound....
on an old V8 i recall it as more of a ping... like bouncing a bb pellet off the side of an engine block...
this is something completely different than all of those....
and to go along with my other post about "not trusting the knock sensor" when i hear this noise i am speaking about... the knock sensor is 0.. and shows no sign of knock in sight....
but yes, i do have some files. they are on my laptop, so i will post them shortly.
And yes... i am new to tuning.... But so far i have just been following my books and such... and so far i have to say that i am not too thrilled with the "professionals" to give an example... they said "run the largest spark plug gap you can without misfire as this will allow the largest spark to begin combustion. Well i was able to get up to .07 gap before misfires.... and my gas milage and power went to sh!t. so much for "largest gap possible without misfire" Now i am back to .30 and things seem fine....
another example.... everything i read says you want the most advance you can get without pinging.... well as i mentioned... i had some CRAZY advance.... i think my last runs were showing close to 80 degrees of advance in some situations... and i still showed no serious KR... at least not much more than the lo-octane gm reflash timing.
So yes... i have been going out on a limb here... taking what people tell me and seeing how it works. what happens if...
but my car is a lil odd... it doesnt seem to quite follow the rules everyone else lives by.... like most people cant even START their car on .07 gap... mine ran just fine (just no power or mpg)
i am not saying i know better... i just know what i see. and i am telling you what i am seeing... and hoping someone can help me to make sence of it.
ok and if it is detonation (or knocking or pinging) then why doesnt the knock sensor detect these???
i am going out right now to do some runs and post up current data.
be back in a few.
ok... well i am still confused....
at one point in my test drive i heard the hairbrush noise, and there were KR peaks to match...
then a lil while later i punched it and got what i know to be KNOCKING... like WOWZERS!!! pulled over and dropped the timing....
but oddly enough.... when the knock was BAD... there was no KR value anywhere near it.
my car confuses me...
um.. er.. ok... it wont let me post a file... um... ok well give me your address and i will email it to you...
at what RPM\LOAD\and how advanced are you,
what injectors?
i was runing LSJ injectors, 24-37 avd, .970-.965 MV and would pick up 0-2 KR through out the RPM range, with soild mounts, and not injecting water.
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
Actually, sometimes... if the knock is bad enough the sensor wont pick it up. Its calibrated for certain sounds and frequencys. Thats what a dyno tuner told me.
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