Anyone had anymore time to play with this? Used a set of det cans to double check what gets picked up?

What input should we be using for the knock module on the MS3x for the incoming signal? I didn't build my MS3x, so I'm not sure how it is wired.

I want to make sure I don't pick a random input, then find out I have a conflict.

EDIT: Please confirm

I am just running the K1 wire from the knock module to a spare port on the DB37 so that I can use a connector on my DIYBOB which is where the wire from the knock sensor will connect.

The knock module can be wired to any unused pin on the lower DB37 or the DB15 on a V3.57 board. The I/O it uses are mostly the LEDs, so you can't use "LEDs spark" mode with it.

you dont have anything on the LED outputs. So bring your knock sensor in one of the spare inputs and run it to K1 and done. Dont forget the wire on the daughterboard youll also have to add.

What spare inputs do I have? There was a wire from the knock module to the daughter board, then I ran k1 to a spare pin on the mainboard DB37, then connected the db37 pin to the knock sensor.

Here is the graph, but it doesn't look like y8s at all, so I think I must have done something wrong.

https://www.miataturbo.net/attachmen...ine=1348963989

maybe this is covered but does the NB miatas use a hardware filter on the signal from the knock sensor, a knockbox if you will?

That's not correct at all - either the knock module is not connected properly inside or your knock sensor is not connected/busted.

How should it be connected? Knock module ---->spare input----->db37----------->knock sensor?

If the above, then what spare inputs are acceptable?

OK, it seems like I am getting a reasonable signal now. The hard part is determining which is knock that needs to be removed. The numerical value increases with rpm, but it is the difference in applitude at each new baseline that I am looking for. i.e. At idle I see about 10-20 as a normal value. Cruising at 3000rpm I see from 20-30 In boost the norm value seems to increase to 50 or more. If I see a value that is 25points higher then my perceived baseline at any point I will start to pull timing and see what happens.

https://www.miataturbo.net/attachmen...ine=1349043331

From the engine to the ecu. Knock sensor ---> knock box ---->ecu pins.

The knock box is supposed to act as a filter and get rid of all that noise your seeing.

That's my understanding.

I plotted knock, rpm, and map using MLV with map beign on the z axis. In just my shore run it appears to show a nice exponential curve as the rpm increases. I believe this exponential trend line could be used as the normal base line for referencing knock spike amplitude. Hence you can go with a rule that says you will retard knock for anyhng that is 25 points above baseline for a given rpm. I don't think it would be correct to just reduce spark anytime the value was above 25 points.

Here is my quick and dirty baseline. More testing will need to be performed to establish firm numbers.

idle: 15
2000: 18
3000: 20
3500: 30
4000: 38
4500: 50
5000: 70

Sounds about right. I'm having about the same numbers on the MS2.

It is totally possible to knock above 6000 rpm.

What are you using as your knock determinate? 1.5x baseline, 2x baseline? I haven't quite figured it out.

I do notice that cyl 3 seems to result in the largest spikes. I pulled some timing out of my map last night, but I'll have to wait until the weather clears up to test it.

Surprisingly I found quite a few spikes out of boost. 2500-4000rpm in the 50-90kpa range.

I pulled about .5 degrees if the spike was 25pts or more above baseline.

This might be helpful for visualizing baseline. I haven't tried it yet.

Re: feature request
by LT401Vette » Mon Oct 01, 2012 5:00 am

In MegaLogViewer you can create a custom field that will average over a set of records.

Custom Field Name: Averaged Knock
Formula: ([knock cyl# 1] + [knock cyl# 2] + [knock cyl# 3] + [knock cyl# 4]) / 4

I get about 13-15 at idle on my knock graph
and 25-35 under boost at 4500
and up to 50 when boost is building and enrichments haven't caught up yet.

On my MS2, I have a "knock threshold" logged value. I put the "knock threshold" and the "DSP knock value" in the same MLV plot, and program the knock threshold settings so that the threshold is about 10-15% higher than the DSP knock value.

Is this custom reverent awesomeness, or something you can spoonfeed a "how to" to the group?

I've been playing with the scatter plots in MLV, and I think I'm able to see some useful data. I'm going to try to use the code above to plot the trendline along with the cylinder I see the most exaggerated knock spikes.

Maybe knock vs trendline vs rpm and knock vs trendline vs map

Enhanced MS2 awesomeness:

https://www.miataturbo.net/attachmen...ine=1349113720

so that's what the MAP signal looks like when you have N/A with ITB...

No ITBs, just a squaretop manifold.