How much knock volts correlates to how much knock retard?

[7055]

Anybody know? For example 1 volt of knock is how much knock retard? Or is there even a direct correlation? I just did some pulls recording with the scanguage but I thought I had it on Knock Retard when it fact it was on Knock Volts. It did not occur to me until I looked down and saw knock at idle.

[forcefedjunkie]

Generally speaking the higher the knock volts the more knock retard, but it's not that simple. The knock sensor is a microphone that picks up a lot of things other than cylinder knock. The PCM has filters that determine what is truely knock and in turn calculate the proper amount of spark retard to eliminate it.

Todd

[Philth]

I've heard from reputable tuners that anything under 3.0* KR is not actual knock. Don't know if this is true or not.

[7055]

I figured it might not be that simple, thanks for the responses.

3KR really? Or 3 volts?

[Philth]

3.0* knock retard. I don't mess with the volts reference usually.

[Monster]

How much timing is retarded for every count that the pcm thinks is knock. Like is it 1 deg for every count or is it higher then that?

[never2muchboost]

theres a crystal in the knock sensor that vibrates and creates an electrical signal..it also picks up a lot of noise. the noise is linear with rpm so a filter is used to wash out the noise so what you see is a result of knock voltage minus the correction table= actual knock on the sensor it will pull back timing according to what it sees. many things affect it such as solid mounts etc.

[Monster]

But is there a definite correlation between the amount of "kr" the pcm shows and the amount of timing pulled? I understand false knock is filtered but Ive always wondered if its 1 deg of timing pulled = 1kr and 2kr means 2 deg timing pulled or if 1kr could actually be 2 or 3 deg being pulled do you follow?

[never2muchboost]

Quote: Originally Posted by Monster

But is there a definite correlation between the amount of "kr" the pcm shows and the amount of timing pulled? I understand false knock is filtered but Ive always wondered if its 1 deg of timing pulled = 1kr and 2kr means 2 deg timing pulled or if 1kr could actually be 2 or 3 deg being pulled do you follow?

what im saying is there is no direction correlation between voltage and timing pulled. the stock cal is set for a stock motor with stock parts if you put solid mounts and start changing internals you change the natural frequency of the engine.the amount of knock pulled depends on what the ecu has learned and the amount of timing pulled in degrees and fuel added is whatever the ecu has learned. i dont know what the min/max threshold is or or the hysterisis is..dont know if anyone does except for maybe guys who have unlocked the pcm

[never2muchboost]

so 1 volt of knock im pretty sure would equate to a whole heck of a lot more timing pulled than 1 degree.if 2 volts knock was 2 degrees pull there would be an awful high pile of cast iron laying around

[Monster]

Quote: Originally Posted by never2muchboost

so 1 volt of knock im pretty sure would equate to a whole heck of a lot more timing pulled than 1 degree.if 2 volts knock was 2 degrees pull there would be an awful high pile of cast iron laying around

I follow you I generally was subtracting 1 deg of timing for every count of knock I was getting but 1 deg didnt always solve the problem... Interesting ... thanks

[forcefedjunkie]

Knock retard is in degrees, so if you see "1", that is one degree of advance removed. Knock counts is something different, I'm only familiar with this in regards to GM vehicles. It's a measure of the length and severity of knock, which plays a role in how much timing to take back.

Todd

[up_in_boost]

i did a pull looking at both settings. Knock retard and knock volts.

I did a pull and it read 8 knock retard
then again using knock volts and it was 1
So do the MATH...

my .02

[7055]

My math says your engine's going to blow up

[up_in_boost]

Quote: Originally Posted by 7055

My math says your engine's going to blow up

Thats what i thought
Compression check shows different.....