I've had my vehicle tuned already and was not happy with the results, so I started diving into it myself. I am in the process of starting my own tune and I want to make sure my knock voltages are in check. But being that it was already tuned, I have always logged the "knock 1 volts" as my data. Looking over the install notes for the AEM V2 it looks as if the ecu interprets the knock sensor under "knock #2." Most of the videos and research I've done points to people looking at "knock 1 volts" data though. Is this wrong? Are the volts under "knock 2 volts" what I should be looking at?

 

I did some logs last night and it looks as though knock 2 is also registering voltage. This adds to the confusion even more.

 

#2 knock is available input for a knock sensor (as marked)
#1 knock is plug N play (as marked)

if you have a stock harness the knock input will be #1.

Now I'm all about people doing things themselves but if you logged both the knock inputs and still were not sure which was actually the knock sensor data after looking at the log you may not want to try tuning yourself until you have a little more time to take an efi university course or similar.

whats going on with the car/tune now? I assume not running smoothly or making the power you were expecting?

 

Both knock 1 volts and knock 2 volts were registering voltage which is why I starting looking into this. I called AEM to verify my hunch, and they said I was correct that Knock 2 volts is the actual factory knock input. From the factory, there is NO pin in C3 which is where the AEM gets it's "knock 1" reading from. Pin C22 however is for the factory knock sensor. C22 is what the AEM calculates "knock 2" from. So when watching for knock, one needs to be looking at Knock 2 volts.

I asked the AEM tech supporter why I was getting voltage on knock 1 since there is no input for it. Apparently the input is picking up voltage from internal cpu processes. I did some more research and found that the AEM V2 has two knock processors on the board. It appears that they may share a data line on the input channels. This could account for the voltage reading on Knock 1 as well.

The car was severely down on power (around 80hp). I found out that the tuner had the knock control turned on, but it was set way to aggressively. it was pulling timing and adding fuel at the onset of 0.5 volts of knock. To top it off, it was doing this based off the wrong knock sensor. It is a bit alarming though that the supplied calibrations from AEM have the wrong knock sensor selected as well.

I have since completely redone the tune (the timing map was pretty far off as well) and I'm sitting at the whp level where I am supposed to be for my setup. This is based off of virtual dyno which I know isn't 100% accurate, but it is pretty darn close. My first setup I made 386whp on a dynojet. I went home and did a virtual dyno run the next week and it came back at 382whp. That's close enough to give an idea for me.