NiklasFalk

iTrader: (1)

That "filter" could be called infite I guess .
Why bother listening for knock when there can't be any.
So it only listen for knock in the small time windows, otherwise it just don't care (smart way to deal with noise).

Would it work with less exact crank angle sensors (e.g. OEM) or would it require a 36 tooth wheel or similar?

Btw have anyone tried Fourier Transform analysis of knock (as a chemist I'm quite familiar with NMR, which in principle is analysis of the squeel molecules sends out after you kick them)?

JasonC SBB

No, it just goes like this:

Knock signal -> bandpass -> Amplitude Detector -> windowing -> software

Up until the windowing, it's just like an AM radio, which was invented, oh, like 100 years ago. I can design one using a single 8-pin op-amp package. The windowing will be triggered by the software and can use a "CMOS switch".

Techsalvager

Here is another solution for anyone that wants knock windowing

http://cgi.ebay.com/ebaymotors/Knock...item3a69ed9532

JohnP

SafeGuard with individual cylinder knock retard was released in 1991. Features included constant energy dwell control with internal igniter and adjustable rev limit.

The detector employed a knock window, but this feature was not disclosed until about 2003.

The processor was an HC11, running at 2MHz bus speed. All the code had to fit in the internal 2k EEPROM.

The detection and thresholding algorithm is elegant, wish I could show it.

I was doing a spark energy test earlier this year, and fired up one of the first gen units, circa 1995. It made 90 mj firing a plug, 109 mj dumping the coil into a high voltage zener string:

http://www.youtube.com/user/strokema.../6/wHtI1FOBKJ4

damir130

**** windowed knock detection. We need ion sensing capability. Why has that never progressed?

Reverant

iTrader: (10)

Because those that have the technology try to keep it for themselves? On the other hand, the MS-II had things like nitrous control, but no A/C control. The reasoning? Nitrous is used by drag racers, who help get the name of the ECU out more than the average Joe and his POS daily driver that has A/C on it.

damir130

Here you go:
http://vvnet.fi/ville/ion/DIY-Ion-Sensing-2.pdf

Could you take a look and see where the really big hurdles are?
Just getting things to the point where we can start measuring ionisation profiles with a small community of MS users could be enough to kick things off. Dunno how realistic that is, but auto-tune for spark and fuel based on current conditions would be nice.

miatauser884

iTrader: (11)

or AMAZING!

Is the idea that you used the wideband, the knock window,a dn the theoretical point of diminishing return to autotune spark? It sounds liek the knock detection is the most complicated part. There seemed to be plenty of theory in one of Hustler's threads about tuning spark and where the point of diminishing return is located in the spark table.

y8s

iTrader: (8)

I'll donate to a megasquirt 3 compatible PCB design.

I've got easy access to 12V, regulated 5V, ground, and whatever comes from the factory harness connected to the sensor inside the MS3 box. keep the overall height to under 3/8" and square footage to less than an inch and a quarter square and it should fit easily.

Input would be the sensor itself, output would be an analog signal strong enough to clearly distinguish knock from noise and place the threshold line appropriately. I think it's 0-5V but I'd have to check with the dev dudes. Ken tells me the analog portion may not even be operational yet.

Windowing is all done in software.

Whattaya say?

damir130

The idea is that you measure when peak cylinder pressure occurs and you tweak ignition timing so that the cylinder pressure does the maximum amount of work during a cycle. The result would be more torque, which is what look for while tuning spark on a dyno.

The knock sensing capability you get more or less for free as the whole ionisation profile goes to hell during knock and is easily detected.

I dunno how accurate you can get this stuff, so maybe you would still need to calibrate on a dyno. But perhaps tuning/correlation could be done quicker, or it could be used to monitor and correct for changes in circumstances: fuel burn rate (octane, temp, additives), humidity etc.

Saab was running ION sense a long time ago. BMW is using it on most cars in their new range. Maybe it is to far of a stretch if even windowed knock detection is beyond our capabilities.

miatauser884

iTrader: (11)

I would also donate money to this project. Brain is working on my MS3x at the moment. If this is something that could be implemented quickly, maybe he would be willing to use my MS3x. That would eliminate the need to buy a whole MS3 test mule.

The downside is that you would be relying on my inexperience and I would need some hand holding for testing. My wallet is open to give donation.

miatauser884

iTrader: (11)

Even if it didn't end up being the end all be all of spark tuning. It would be nice to have the autotune feature with a pair of electronic det cans as back up. Spark is increased until knock is detected. Then based upon a little theory the spark is retarded by a predetermined number of degrees. Those that want to be more aggressive can do as they wish.

miatauser884

iTrader: (11)

I'm not sure if this is possible, or detectable. BUT here goes. If it is based on peak cylinder , is the MAP sensor sensitive enough to notice the change in pressure if the engine is held constant but the timing is being changed? So if I were able to get on a flat piece of highway in the gear of my choosing to keep the car at a steady rpm and then the timing were adjusted, would you see a difference in map signal?

Where I am headed with this: Could you then have a test area in tuner studio that allowed you to like your pulsewidth for a predetermined number of seconds. Basically a tunerstudio cruise control. Once activated tunerstudio listens for knock while adjusting the timing.

Reverant

iTrader: (10)

How would the MAP sensor be able to see the pressure inside the cylinder, since the cylinder is sealed and any pressure is vented through the exhaust valve first?

miatauser884

iTrader: (11)

I was wondering if the ouput through the turbo would be slightly increased. Higher cylinder pressure should equal higher exhaust pressure, which powers turbo, which plumbs into intake.

JasonC SBB

No, when spark timing is less retarded from optimum, cylinder pressures go up and then less energy is in the exhaust. Turbine Inlet Pressure (TIP), goes down. And no, there are too many other variables affecting TIP more, to be useful for spark timing tuning, even in an n/a car.

JasonC SBB

Fail because you can have too much timing and NO knock.

The one and only ECU that had a "best timing finder" feature is the Adaptronic, and mysteriously, nobody was interested in the feature. Such that they removed it in later revs:

https://www.miataturbo.net/adaptronic-63/anyone-play-ignition-auto-tuning-yet-42882/
http://adaptronic.com.au/forum/index...ic=252.msg7487

The way it does it, is it adjusts the timing several times per second, then detects if the acceleration improved or not. No mean feat.

JasonC SBB

Someone else has to do the PCB layout because I don't like doing it.

y8s

iTrader: (8)

put it in an eagle pcb compatible format and i'll do it... or maybe altium and I'll coax a coworker into doing it.

miatauser884

iTrader: (11)

That is where retarding the timing based on where the theoretical optimum timing is based on knock. If research suggested that knock occurred 5 degrees past the optimal timing configuration, then retard timing by at least 5 degrees after knock is detected.

I know I should probably stay out of this conversation since my expertise is zero, but I'm learning something.

Is one of the GPS transponders that people are using for lap timers sensitive enough to use it for calcing timing based on acceleration? Probably not. It seems like a speed sensor used while locking in a fixed pulsewidth would work. Question is, where do you mount a generic speed sensor.