Having Knock reader in dash pays off!

[Step-a-toe]

Certainly internally proud of self for monitoring my EA82T knock control circuit the past 200,000 km.

Simply by finding a Volt display capable of reading zero volts. I found one making the claim, now seller has revised the range.

In dash reading displays from ~1.7 - 4.5V depending on what the two pin sensor is reporting.

Just the other day I noticed readings higher than its happy 17 yet with only light load. It should not budge until revs are up and I squeeze the loud pedal a bit.

 

I am yet to investigate the cause but have disconnected the big fat and black round connector and she runs better ( in my head?)

I have run these Series Ones before with the KCM connector accidentally disconnected for months with no hint of adverse performance

 

 

[idosubaru]

Nice.  Yeah I’ve run with them disconnected too when the plastic top of the knock sensor disintegrates.

how were you able to read the output again?  That would be great.  Some things have such fast update rates that displays can’t capture or show it in a meaningful way. I’m unsure which sensors this is true for or not.  How do you know that’s not the case here?  

[GeneralDisorder]

You aren't detonating at light load unless it's VERY lean so this is very likely false knock. Remember the knock sensor is just a microphone tuned to a specific frequency. It can *hear* anything though and anything that is rattling or loose will set it off. 

Knock modules of that era will often output a square wave pulse to indicate a knock event to which the ECM will respond by pulling timing and then adding it back in at at a specified recovery rate. I doubt a simple voltage gauge is going to be all that useful. And at light load like that it's not actual detonation anyway so chances are you are "reading" meaningless data and just confusing yourself. The real answers are to see what the ECM is doing with timing, and how much it is pulling and in response to what input from the knock module. A voltage gauge tells you basically nothing. You need at least a scope trace but even then you really don't know what the ECM is doing with that data.

GD

Edited January 27, 2021 by GeneralDisorder

[Step-a-toe]

Been monitoring for a decade , having first used a panel analogue needle display, then an LCD display, now a red LED digital display.

The unit requires a power and earth connection then the input from the Series One and possibly the EA81T is the same...black/white wire at coil with white plastic female test connector, so usually seen doing nothing

The interactive experience is something being engineered out of cars these days. With this I can hear pinging, look down to see reader is higher than its nominal cruise voltage of ~1.7V. 

If pushed hard enough I can hear the pinging, feel the timing being retarded and see the higher reading.

 

Brain then tells right foot to back off a bit ..

 

 

 

[GeneralDisorder]

If you can hear detonation on a Subaru engine, you have already FAR exceeded the point at which you are potentially causing damage and really Subaru engines should be kept below the point that any detonation is audible by the knock sensor. 

GD