Hello,

so my knock sensor output voltage is a flat 0.2v & I dont have a spare knock sensor to throw in there.

I was under the impression that the sensor is to receive 5v, however i havent located confirmation of that....

anyway, with no spare sensor, i wanted to confirm 5v power with the engine running & i get ZERO Volts measured at the union between the engine harness & knock sensor connector. Either wire, nada.

i swapped ecu's, same zero reading.

I looked at fuses & all ohm fine, that were checked, which had the engine symbol.

Does anyone know where the power comes from, to supply the knock sensor?

also, has anyone ever confirmed the voltage feeding a knock sensor on their evo 8/9?

any ideas, suggestions, insight would be greatly appreciated.

TIA

 

if someone could put a volt meter to see what their evo produces @ idle when measuring voltage from the electrical harness side of the knock sensor connector, that would be greatly appreciated.

Vdc.

also, please let me know what color wire you are measuring the voltage from.

Thanks, aby

 

This my not be exactly what you need, and also i am on vacation. But i do have my AEM Logs on my lap top of my knock voltage when at Idle. Should be under Raw Voltage, But changes very little as i drive, Mostly do to the filtering. But under 3000RPM there is only a 0.1v filter at those points.





I have not checked myself but the Volvo sensor should be the same.

https://www.volvoclub.org.uk/faq/Eng...ngaKnockSensor

Sorry i could not be more helpful. i am far from my car.

 

Thanks for your input.

However, i am looking to see what the voltage is coming out of the harness, supplying the sensor.

 

I don"t have too much time to explain, but the 5v Reference is in the ECU....what goes to the sensor is a much smaller value.

 

Aby,

What was the reason for checking the voltage? I'm seeing random knock with the knock voltage barely reaching 0.05 volts. Before this issue it would see 0.5 to 1.5 volts during a pull. To see less than a 1/2 volt during pulls and registering crazy knock sum tells me something is up. The voltage to the sensor is 0.2 volts.

Did you figure it out?
TIA

 

There is no 5 v.

The sensor it's self generates a voltage when it gets excited.

Like here.


If you want to test to see if it works or not, tap it with something hard, connect an oscilloscope to it.

You wouldn't want to take too much notice of that previous link.

 

None

 

Thanks!!! So what I gather is that there is no source of power to the knock sensor. A Piezoelectric element in the knock sensor generates voltage when vibration is applied to them. The ECU will determine if that is knock.

So in my case the knock voltage is very low (0.5 or less), but the knock is high (9-36 counts of knock) at cruise, spool, partial throttle, or WOT. Used to read below 2 volts during pulls without any knock or very little knock (1-2 counts).

My theories are the knock sensor is bad and can't create enough voltage due to damage and/or the voltage is high enough from the sensor, but the wiring to the ECU is bad or starting to fail.

Am I missing anything?

BTW, the knock sensor was pulled off the original motor that threw a rod/piston, etc.

 

How did you measure the voltage?
It's AC not DC and it's about 12KHz.


If you disconnect it, then when you drive, you'll get a constant 7 to 9 knock count once you go over a certain RPM. That might also depend on the ROM used.

 

Thanks for the response. Yes, I had a car on a dyno that had the knock sensor unplugged and it read 9 counts at all times.

This other car has the sensor installed and plugged in. The voltage during a pull or cruise is logged through EvoScan. The voltage measured at the harness/plug was with the key on with a multi-meter. But I get that it won't read anything. I want to test one on a vise and see if it will show a voltage with a hammer hitting the vise while the sensor is grounded to the vise.

I thought this was a good video:

 

Hi I'm Brian.........
I'm wasted.
But that's a GM knock sensor, not a Mitsubishi.


At 5.00 ish, he's got a GM resonant sensor in one hand and a Bosch flat response sensor in the other.
They work in completely different ways, you can't swap them.
No such thing as pre detonation, it's pre ignition and it won't trigger the KS.

At 6.16 he's on about 6 to 9 KHz.......but resonant sensors don't detect frequency, they detect the initial shock and then carry on oscillating at their tuned frequency (like an electronic tuning fork), for a GM sensor , it depends on the part number but will be between 10 and 12 KHz
For a Mitsubishi sensor, it's the same, it depends on the part number.
There's no resistor in a Mitsubishi sensor so you can't test it with an ohm meter.