For anything you'd like to see added to Speeduino
By dazq
#14785
Well we could use it but as others have said possibly not the best use of remaining mega2560 capacity, but a good building block for either a coprocessor (you could use the serial 3 interface route)or for the future when the teensy 3.5 boards come on stream
Alternatively another member once mentioned a Canbus knock module, this now could be added if so inclined...
By dazq
#14794
Klotzy550(i think) raised a bosch oem module that used can to communicate for knock sense
By punisher454
#14809
Seriously, I'd just hook up a GM knock module and use it to datalog the knock counts. Then review the log and adjust timing tables.
Thats how I do it now when I tune GM OBD1 computers. The knock module will pick up signals you cannot detect yourself, good tuner or not. After a test drive I review the log and look at the knock counts histogram and adjust the timing tables in those cells. Really simple, and effective.

Also, the different knock modules have their filters calibrated according to bore size.

listening for ping by ear vs using a knock sensor/filter is about the same as tuning by just looking at the sparkplugs compared to tuning with a wideband.
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By PSIG
#14811
I am in no way against a solid and functional knock detection system, although I have concerns (below). A common knock module is not universal, and yes they pick up sounds you can't with the bare ear, and why they often return false positives. It's fine if it can be tuned for the engine's knock frequency, and also tuned to filter noise of that engine design, and detect the frequency in the pattern that is actually knock. That's the big issue. As an analogy, sensing knocking sounds is easy but this is like trying to hear one person, in a sports stadium with thousands of noisy fans, and the guy you're trying to hear is speaking in a foreign language. Noise, frequency, pattern. Just to complicate things, every engine has it's own response signature (different stadium, country and language). So, unless you have a pre-matched filter and interpreter (such as a GM sensor and GM tuned (matched to that engine) module on that GM engine type, tuning the knock detection and filtering system is a considerable task to do reliably and effectively. GM spent millions developing theirs and it's not 100% either. If it's not as reasonably reliable and effective, it's more dangerous or inhibiting than nothing, and that has been the case so far with 'universal' systems for all our engines.

Without that developed OEM-type setup, the alternatives are many and generally use more than one, such as plug reading with EGT monitoring or electronic ears on piezo sensors. Each is a reliable method if used properly, and does not require lots of skill or experience to use effectively, as proven by decades of amazing engines not using KS. Sure, I'd love to have an auto-tuning knock system that works 100% on any engine without destructive testing and I hope one is developed soon, but until then we have to use the best available methods. Why say this? Because you want to create a microchip program that will do what we can do today, but better. What will that take? Well, legitimate questions to define the KS project: Without a dedicated pre-tuned knock system as described, what other effective methods are suggested for Speeduino users today, and how do we translate those to this KS system? Can we teach users how to then tune a knock system without damage, as it (and the user) need to see/hear and identify that engine's knock to know what it's avoiding? How do you prevent the common problem of users abusing it by allowing it to "control" timing, losing power overall on both retard and over-advance, and hitting knock with potential damage every 4 seconds (if the module is tuned well)? What is the true purpose of a Speeduino knock sensor, and is it potentially more dangerous than safe in these regards? This ad-hoc project needs to know these answers and more in order to have a definition of capability and usefulness for it to succeed. I want to see it really work, rather than hit unexpected hurdles, slowing or stopping the effort.
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David

Actual knock sensor output (resized). It's your job to tune it. Do you see any knock? Where? How do you know?
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OK, so through a spectrum analyzer should help make it easy for a newb, or an expert to develop auto-tuning for it:
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Ion-sensing ignition timing control is next, making KS irrelevant. ;)
By Shonky
#15672
АлександрГусев wrote:
Ion-sensing ignition timing control
A killer feature for sure. I am voting for ion current knock control instead of audio knock control
Saab use ION sensing to great success!
By Shonky
#15712
ION sensing on Saab's T5 and T7 ecus is done in the ignition cartridge which will only fit the correct engine however the newer t8 ecu use coil on plug with ion sensing which may be worth investigating
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Page 159 in the T5 manual gives a bit more info: Linky

It's pretty slick stuff, when the Saab ecu sees something like 10 litres of fuel go in the tank it'll increase the ignition timing for a few miles until it detects knock to essentially measure the quality of the fuel
By androidcho
#15718
I've heard that VW FSI engines use the same tehnique for knock sensing, but can't find enough info right now. Also, they tend to have only 1 model spark plugs available.

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