Is the 5mge knock a Resonance or Mass piezo sensor

[_gear2]

Couldn't find the answer despite my searching - but is a Is the knock sensor on a 5mge a Resonance or Mass piezo sensor? Also are you still able to do the meter test on the bench - can't I think of a reason why it wouldn't work.

[thechuckster]

i understood most knock sensors to be piezo devices?

[beerhead]

I'm not too up to date on how they work, but have been told the new generation knock sensors like on my 2GR are a new breed and more accurate, anything old will be the less accurate of the 2. I've got a few spare late gen (2006 onwards) knock sensors if you wanna play with one on an aftermarket ecu.

[TERRA Operative]

Pretty much all Toyota knock sensors up to the turn of the century (where my experience ends) contain piezo elements.

[_gear2]

I'm not too up to date on how they work, but have been told the new generation knock sensors like on my 2GR are a new breed and more accurate, anything old will be the less accurate of the 2. I've got a few spare late gen (2006 onwards) knock sensors if you wanna play with one on an aftermarket ecu.

Are you able to do that use knock sensors from different engines? I thought they would in someway be tuned (if that's even the right word) to a specific engine. (This would actually be really help full as I might need to go to the wreckers to get one and the one on a 5mge is in a bitch of a spot)

Pretty much all Toyota knock sensors up to the turn of the century (where my experience ends) contain piezo elements.

From my reading the misinformed internet the mass piezo pick up any noise, but a piezo Resonance sensor picks up a specific frequency is this correct? or is someone spinning a yarn - im assuming most older sensors would be the mass type if this is true.

Doing the volt meter test - where you run the multimeter into the knock sensor then bang near it - that will work just on the bench? (i cant get mine to produce voltage - so im assuming its no good but want to make sure)

[beerhead]

You take on mass and resonance piezo pickups sounds right.

BTW the knock sensor isn't tuned as such, just the ECU knows the sound of good background noise and knows the sound of a knock. If you have an aftermarket ecu I'll send you a late gen knock sensor to play with (free of charge). I was told they're the bomb compared with early gen knock sensors, but if you have an early factory ecu a late gen knock sensor won't do you any good.

Are you able to do that use knock sensors from different engines? I thought they would in someway be tuned (if that's even the right word) to a specific engine. (This would actually be really help full as I might need to go to the wreckers to get one and the one on a 5mge is in a bitch of a spot)




From my reading the misinformed internet the mass piezo pick up any noise, but a piezo Resonance sensor picks up a specific frequency is this correct? or is someone spinning a yarn - im assuming most older sensors would be the mass type if this is true.

Doing the volt meter test - where you run the multimeter into the knock sensor then bang near it - that will work just on the bench? (i cant get mine to produce voltage - so im assuming its no good but want to make sure)

[_gear2]

ahah well this is just going in my 86 cressida so i guess its off to the wreckers for me. Thanks though beer appreciated.

[toyoda]

"Doing the volt meter test - where you run the multimeter into the knock sensor then bang near it - that will work just on the bench? (i cant get mine to produce voltage - so im assuming its no good but want to make sure)"

Make sure you have your Voltmeter set for AC NOT DC.
Oscilloscope is best.

Toyoda

[beerhead]

If you unplug a knock sensor and the car drives the same you know its stuffed. I accidentally left mine unplugged on the Camry one day and it wouldn't rev over 3 grand.

[MWP]

BTW the knock sensor isn't tuned as such, just the ECU knows the sound of good background noise and knows the sound of a knock.

I think this is incorrect.
Ive seen it mentioned many times in various places that knock sensors are tuned for a specific frequency on the engine they are made for.
I have no other proof though.

... this has me wondering what these new 2GR sensors are though. Anyone know more about this?

[TERRA Operative]

The sensors do seem to have a frequency response specific to the engine they were designed for. I tested a few on the oscilloscope a while back and they have a definite resonant peak.

I'll try to find the screenshots from the oscilloscope.

[TERRA Operative]

I only tested two, but here are the screenshots. The purple is the frequency response.


Gen 4 3SGTE (resonance at 10kHz)



4AGE Silvertop (resonance at 7kHz)

[beerhead]

I assumed the ECU had something to do with it because you can listen to knocks with the new adaptronic ecus with headphones and you set a base noise level in the ecu on the dyno with quite low timing before you start pushing things.

The 2GR sensors are a different animal hey. they don't screw into the block, they are a circle and have a bolt hole in the middle. They appear to be a toroidal pickup of some sort. Will get a pic when I go out to the shed later.

[toyoda]

The resonant type KNK sensor has a natural frequency which is the same as the KNK frequency of an engine (+/- 7kHz)
The non-resonant or flat type knock sensor has a flat characteristic and can detect approx. 6kHz - 15kHz frequency (own frequency is +/-25 kHz).

Resonant Type is tuned to the engine - Non Resonant type Ecu is tuned to the knock of the engine.

Non resonant is Black Plastic with a hole in the middle for mounting.

If you work on a Vee Engine make sure you connect the right sensor to the right wire and the Left sensor to the Left wire.

Toyoda

[MWP]

I assumed the ECU had something to do with it because you can listen to knocks with the new adaptronic ecus with headphones and you set a base noise level in the ecu on the dyno with quite low timing before you start pushing things.

All ECUs will have a bandpass filter, even those that use "tuned" knock sensors.