SiiNerGia

Hello everyone! First of all, I would like to say I'm a complete beginner, I have never tuned a car and I'm currently in the moment of finding all the information possible about the topic.

After a couple of weeks of investigating, I decided that Speeduino would be the best board for me since It has the features I need, the development seems solid, and of course, the price.

However, I have found that apparently, it doesn't have any kind of knock protection, and I don't completely understand how is it even remotely safe to run an ECU without it.
As far as I understand, the standalone Miata engine has a knock sensor installed and the OEM ECU handles it, so it seems weird that the Arduino doesn't take that as an input to handle it.
It is also my understanding that in the OEM setup, the knock sensor is an important part of engine tuning, as the engine is constantly dancing between knock and no knock to find the correct timing advance.

My question is:
How is it possible that in a standalone ECU setup, the knock sensor is ignored? As I understand, one of the main points of having a standalone ECU is being able to squeeze power out of your engine (across many other features), and I don't understand how can this be safely done without any type of knock protection. Is there some aspect of the tuning process that I'm missing that allows me to safely make a tune without the risk of causing a knock, either at the time of making the tune or in the future?

adam86

no knock sensor in the speeduino units. The knock sensor in miata is only in the NB and up, I think.
Many standalone ECU don't support a knock input, only the higher-end ones usually have it.
Effective knock sensing and implementation is not an easy task = low cost ecu don't have it.
make a pait of detcans or you cant buy an after market knock sensing unit for tuning like this.
https://tunernerd.com/en-ca/products...monitor-pro-v4

SimBa

I'll add in, that there has been work done towards adding some type of knock protection (not detection) to the Speeduino firmware. I believe the signal from the sensor still needs external processing before going into the ECU.
That code is not enabled, but apparently a few tweaks to the INI will enable it. I don't believe it has been tested much, and I don't know much more than that.

There was also SpeedyKnock, which was going to be a standalone knock sensor developed by Josh from Speeduino, but I believe that project has stalled/died.

There is definitely interest in getting Knock sensing/protection supported in Speeduino. Knowing the community and how it's growing I wouldn't be surprised if it is implemented in the next 1-3 years.

4sfed5

None of the NA miatas had knock sensors and most of the NBs didn't either...
you don't tune with a knock sensor as most are only half a$$ed solutions that don't give OEM knock protection...
Do a bit more research before bagging the speeduino. Most ECUs up until a few years ago didn't have knock sensors built in

Jesse99James

4sfed5, all NB Miata have an OEM knock sensor. You can verify in the dealer parts link by looking under the "What This Fits" tab.

OP, I also had some anxiety about tuning and not having any knock detection/retard safety net. My remote MS3 tuner said it's tricky (difficult?) and time consuming to set the parameters correctly. It takes data logging and testing to induce knock to figure out what is background engine noise and what is detonation. I'd also guess that it's risky testing without a long, live tuning session (or multiple sessions) remotely logged into the tuning laptop. In the time it takes to email logs, analzye, and send a new tune file back, the owner could damage the engine if they left the detonation inducing tune loaded or drove longer than needed while recording data.

I plan on checking with a local Subaru tuning shop that has a dyno (not sure what type). They said they've tuned a few turbo Miata so maybe they can help guide me or I can pay to activate the knock retard protection on my MS3. I haven't yet dug deeply into it as the car is in winter storage but my tuner seemed impressed with my initial attempts at tuning, complimenting me on how far I got before paying for help. I read about tuning detonation retard on multiple ECUs and know the 1.8 BP knock frequency but gain/sensitivity and other settings need to be adjusted. I'd prefer having somebody with experience guiding my attempts, or I'll simply pay to have it setup, if possible.

It's another steep learning curve to climb but it's not necessarily unsafe running without it enabled if timing isn't overly aggressive. After more than a decade of tuning my tuner has very good base maps to start with, has different 91/93 octane ignition maps and takes engine build data into account (likely compression ratio) for safe fuel/timing maps from the first start. Timing should never be advanced to the point that knock protection often retards timing, you only want it as an added safety net in case you get a tank of bad gas. It will ease my anxious mind. Building the engine with forged rods/pistons and nearly every possible upgrade helped, up until I started pushing the limits again. This Spring I'll finish tuning EBC and will be running ~18 psi (GT2560) so my anxiety level has increased.

I doubt OEM ECUs are constantly trying to advance timing just before the point of knock, in some areas it would advance past the point where power increases without ever seeing knock (MTB?). Rather, it's tuned knowing cheap bastards will run 85, 86, or 87 octane on engines that require higher octane. The ECU monitors for knock and likely has a long term trim table to learn where reduced timing is needed. If low octane is used long-term, I could see the ECU getting stuck running less timing and never adjusting back towards the original, slightly more advanced timing. At that point running higher octane gas would not result in more power, until the ECU was reset and the trim tables cleared. I have little experience/knowledge but that seems to make sense.

SiiNerGia

So, unless you have a high end standalone ECU, what is the way to go when doing tuning if you don't have a knock sensor? to just ignore it?

sixshooter

iTrader: (12)

Det cans

adam86

buy a RusEfi the uaEFI is 100$ and supports knock if this is the most important feature for you. The beer money motorsports is 700$ and plug and play version of RusEfi.