Knocklite to MS to pull timing. It works!
 

I have been working on trying to get Knocklite to work with MS (in this case DIYPNP) for ages and now its working. Knocklite has 2 spare wires that can be connected to a TurboXS D-TEC fueling system (not used by us), the yellow wire outputs a constant 5v and when knock is detected it drops to 0v, this is what MS is looking for to activate the knock sensor settings that have been set in tunerstudio. The main problem was the drop in voltage from Knocklite was so quick (microseconds) that MS could not see it (MS needs 10-15 milliseconds).

After much head scratching and help from Richy (Mr Slow on mx5nutz), Jeff Ciesielski (MT.net) and Rob Knight (Everlog Megasquirt), we determined that a circuit was required to increase the 5v - 0v drop time from Knocklite to allow MS to see it.

The circuit diagram is below, Rob Knight has changed it from the original proposed diagram by Jeff. The time is calculated by 1.1 x R2 x C3. Its set to about 10ms at the moment which looks like it is near the minimum time for the Megasquirt to detect. I have also included a pic of the actual circuit that Rob Knight made for me (I really cant thank him enough!! :worship: :worship: ):

https://www.miataturbo.net/attachmen...ine=1327591916

https://www.miataturbo.net/attachmen...ine=1327579574

https://www.miataturbo.net/attachmen...ine=1327579574

This circuit goes between the knocklite input (yellow wire) and the DIYPNP knock circuit pinout (in my case AD1), it also needs a 5v and ground supply. I am pretty certain that this circuit could be knocked up in the proto area.

Here are the settings that I have used in tunerstudio to get the circuit to work:

https://www.miataturbo.net/attachmen...ine=1327579574

I still need to play with these settings to achieve the timing retard that I would like but that should be easy enough.

With everything hooked up and the Knocklite set to sensitivity No1 (most sensitive) I went for a spin, I did a few runs where the knocklite flashed (Noise, not knock!) but MS did not pull the timing, I then made a few settings changes (primaily, pull up/pull down setting) and it worked. On seeing knock indication MS immediately pulled the timing, I could see it doing it on the knockret gauge on tunerstudio. I did a few runs and it worked everytime, pulling the timing by different amounts (3 -10 degrees), I assume it pulls timing constantly (to the settings) until knock is no longer detected (0v - 5v on the knocklite).

Here is a screenshot of it all working, this was a 3rd gear pull. As can be seen, knock is detected - MS pulls timing by 10 degrees - then it recovers (determined by the settings in TS)

https://www.miataturbo.net/attachmen...ine=1327579574

I now need to have a play with the settings in TS so MS pulls the timings I want. All in all I am really pleased with the results, however, I cant take the credit for its success, that goes to Jeff Ciesielski and Rob Knight, without them I would not have a circuit to make this work, so we have to thank them... :worship:

Barry

very cool. now just need a step by step for dummies like me to add it to existing diypnp unit

Barry, this is some clever ----, well done. Innovators like yourself really make MX5, and now MS ownership, a brilliant experience for many others.

Props to all involved for sure.

I have updated the 1st post with the circuit diagram...

I'll build it...my fee is the parts to build one for myself.

This looks to be a well sub $100 knock solution. Most of the cost will be the appropriate knock sensor. It looks like the KnockLite uses a Bosch one.

If my stupid break out board ever comes in, I have another solution I'd like to try out that uses less than half the parts as well (for anyone who is interested in trying it out).

Does anyone know if this is this needed with MS3? It's got a faster CPU...

Faster CPU is irrelevant. But MSIII has it's own option anyway.

Beautiful Baz! Nice work.

Awesome!!!!! Now calibrate that knocklite :)

Do you mean the standard knocklite calibration set up or something else?
Barry

Yup. Calibrate under boost with low timing.

Cheers bud, thats a good idea, so just to confirm I have it right, retard my timing by a few degrees (around the WOT full boost area) then when it comes to doing the high rev bit of the calibration press the calibration button under full boost around 7000rpm?
Barry

Yup, you got it!

Sorry for this stupid question. Where is the 5V come from?

that was a pretty silly question.

5V from the proto area? Just to confirm it . :bowdown:

or anywhere else 5v is available after the 5v regulator.

Just finished this board and installed on the car and everything seems fine!!
It detect knock when the knocklite flash and timing retarded.
But I just notice the fan tune on even the car is off.
The output of the board hooked to JS4 of my MS2.

I am looking to add a knock sensor to my DIYPNP. It looks like the link for to purchase knocklite is dead. Anyone know where to buy one of other knock sensor solutions?

Buy Knocklite - KnockLite by Turbo XS