a way to detect knock... the hard way
 

Well, I was wondering about it and was thinking to myself "hmm... knock is a problem with boosted motors... so how can I pick up on whether or not my motor is knocking, seeing how its not always audible?"

well, this is what I came up with.

a solid wire tapped into the block somehow, maybe drilled or something like that.

now I know the stock TII sensor runs off of air pressure, but I think my idea will work.

well, you have the wire in the block somehow. So you take the wire and run it to an oscilliscope. A combustion event should produce vibrations in the engine that would vibrate the wire and transfer to the oscilliscope. Now I would think that most combustion events would look the same. A knock event should look wild in comparison to the others, even a mild knock.

does this sound feasible to you guys? are there better ways of doing this? (no I don't mean going out and buying a premade knock sensor setup for who knows how many hundreds of dollars...)

I want some of what you're smoking j/k...

That won't do anything.

A knock sensor is what is called a tranducer. A transducer is something that captures some phenomenon and converts it into an electrical signal to be read by whatever, including an oscilloscope if you want to hook it up. A type of transducer is a microphone or a speaker. They convert back and forth between sound waves and electrical impulses, just in reverse.

A knock sensor converts a phenomenon, in this case a vibration, and to a signal. Do you see the difficulty?

Also, by the time you'd detect a knock in a rotary, you're engine would be toast anyway.

well, then why did mazda bother putting one on the TII?

Well the MR2 people often replace theirs with a GM knock sensor and an adapter for it to fit in the stock location.

http://twosrus.com/new/Lower_Frames/...d/atsknock.htm

Then they hook up an LED to blink whenever knock is sensed, so I would think if you have a sensitive knock sensor, you might be able to save your engine when you see the blinky light.

Well in a piston engine a knock or two is fine.

One knock can blow ruin an engine in our cars.

Knocks are pressure shock waves traveling inside the engine. A knock can rip up the apex seals. It's usually due to advanced timing/predetonation of fuel(right?)

Pretty much a knock sensor is like a normal narrow band AF meter. You get to watch the car die but it does nothing.

The right thing to do is get the car on a dyno with a wide band O2 sensor and tune it into a safe AFR.

Why did Mazda do a lot of things with our cars?

hmmm good point :D

Re: a way to detect knock... the hard way
 

This isnt how the stock knock sensor works...

What are u smoking?

He's smoking domokun.

Where do you buy an oscilliscope that reads vibrating wires?

Knock sensors are piezo-electric microphones, so air pressure is technically wrong.



-Ted