1.6 Naturally Aspirated AFR and Spark Map
 

Just looking for a sanity check, no access to a dyno at the moment. Will just be doing ve analyze to begin. Leaned out around 3.5-4k RPM as that is what I cruise at on the highway. Could I go leaner at WOT?

Built the AFR table myself, the spark map is from a base map I got with the ECU from DIY autotune.

Fully stock 1.6
949 Racing U-Bend intake
Racing Beat Header - Test Pipe - Race Exhaust
91 Octane

https://cimg5.ibsrv.net/gimg/www.mia...ad3613d952.png

Those are bad. You want richer at wot, and that spark table terrible. A car should never be run at basically two timing values across the whole range.
DIYauto is known to have put out some truly bad spark maps in their base maps, that should never be used to drive on. Look around, you'll find proper ones or at least something safe enough to start with.

Maximum fuel economy occurs at ~15.4 for ethanol free gasoline (Stoich of 14.7). Running any leaner that that actually consumes more fuel and increases the likelihood of spark knock.

And targeting a superlean mixture isn't nearly as important as getting the car to actually hit the targets quickly and consistently.

Thanks for the feedback guys.
Adjusted WOT to start at 13 and go down to 12.7
Brought leanest sections of the table down to 15.3
Spark map modelled after reply #2 of https://www.miataturbo.net/megasquir...gnition-71921/ by @Joe Perez . Took a few degrees out up top just to be safe. But Joe getting your thoughts would be dope.
Still feeling kinda lost on the spark without a dyno, but it is what it is.
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your spark map is too far advanced. I'd look to reduce your entire map by nearly 5 degrees if not more in certain spots. How are you listening for knock do you have det cans or a knock sensor?

I am not holding out my spark map as the end all be all of good, I know it needs some more work but this is more or less what I run.I have an 03 engine so my compression is higher than yours which means my likelihood for detonation is a bit higher, but I think a table like this would be a good starting point for you.


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Highlight the whole ign map and use the - button to subtract 8 degrees, then highlight the whole 1000rpm colum and add 8 back with the + button. That will put you in the ball park. These engines in NA form make the most power around 30 deg. The lean cruise area needs to be in the upper 30's for an AFR of 15-15.7. If this was a max effort MPG vehicle you could go further, but that's not for most.

That is a decent looking spark map to start with, Andy

I agree Andy's is ok but Justin's is terrible. On Andy's the upper left and lower right quadrent are a bit extreme though.

Below is something I threw together that is similar to what I ran on my NA 1.6. This was on 91 CA gas and with an idle at 900rpm. I left them with the axis value view so that someone who is new to tuning can see how to change these values. It is important to have the ranges similar to each other, AFR, VE & timing. Also to have the correct range. Many newbies have ranges that limit incorrectly. No need to start at 10kpa which is not achievable and finish 150kpa if your not FI. Also I prefer to have a specific RPM that matches the idle.

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I'm quite confused about why going to 36-40 degrees at WOT redline on 91 octane is an issue.

As quoted by @Braineack on miata.net https://forum.miata.net/vb/showthread.php?t=303941

This is stock timing on 87 Octane

Call me crazy? Thoughts?

Re knock sensing, I am in the process of building det cans.

The craziest part is just guessing numbers based on someone else's guesses and then just running with them without a single proper test or way to check that it's not dangerous.

The stock ecu also runs a narrowband, and also runs stoich all the way to midway of powerband. That should not be your standard. if you're advancing timing but not seeing any gains, even if you don't see knock, you're putting completely useless stress on your internals.


If you want to try stuff for science, I fully support this, but make sure to disclose it as such so that clueless n00bs in the future won't use your stuff as standard cause they're too dumb to know any better.

@18psi yup makes total sense, I'll load up andy's spark map and go from there, priority should be getting fuel down anyways.

I find my car cruises on the highway around 75-80kpa, on @LeoNA 's map that would put me in the mid 13's, is running the 15.3 that high like in my map okay? Or tbh I guess that is something det cans and EGT'S is going to tell me... gotta put the time in.

Documenting the next steps for completeness sakes. Built spark table similar to @andym 's scaled down for 12x12 on MS2. Minor tweaks to AFR table in some low RPM areas.


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If your car were mine I would not run 15.3 between 72 and 83 kpa. I'd richen that up a bit so that it is a more gradual transition. The difference between 83kpa and 90 isn't very much and you are jumping 2 whole afr points there. I'd work on your bubble of afr table so that it is a bit less lean from 72kpa and up around your 3500 to 4000 rpm range. Maybe target 14.7, then 14.3 then 13.8 then 13.2 then your 13.1 and 13 rows. Also, I run a bit richer at 100kpa. Roughly 12.6 to 12.7 Your results may vary.

I was running 50-70kpa at cruise and for the smaller 100hp engine it seemed to be more efficient near stoich. Stoich for E10 91oct fuel is about 14.4. I also tuned it more towards power then MPG. Max power is around 12.5-13. I was tracking my car at Buttonwillow sometimes at 90+ degrees. If fuel economy is your goal you could run well into the 16+:1 range with 38-40 degrees, but why, to maybe gain 1mpg extra. The beauty of a stand alone is to be able to tune for more power and better drivability. The OE ecu is tuned to meet emission and CAFE regulations.

Makes sense, smoothed it out a bit, are there any rules of thumb about the magnitude of the slope of the Y-Z plane? units of AFR per Load %? How does that look? Wish I had better intuition but that is something that will come with time I hope. For instance between 85 and 90kpa I am still jumping 0.9, is that to steep still?

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If it were my car I would try richening it up a little bit more but it is starting to look better. Also, your idle areas look very rich. Any particular reason why? Are you also running idle ve and tuning that?

My car is still running batch injection, the car seems to be happy idling in the 13.2-13.4 range, I tried leaning out to like 13.7-14 and it started getting upset. The injectors are 30 years old, it is what it is for the time being. At some point I should do the modifications to go sequential injection but it doesn't seem pressing atm. Ill richen up the 3500-4000rpm "peak" a tenth or two and see how it goes.

Do you think idle VE is worth doing? I didn't really see the point, but I am also serious tuning noob so there is that.

Not to throw more variables at it, but I do have a set of ID1050's around since I was planning to go FI once until all this COVID stuff blows over (getting parts has been brutal here in Canada atm). Would it be worth throwing them in now? I've heard modern injectors help with drivability and make tuning things a bit easier, but also seems super duper crazy overkill right now.

I don't run idle VE. I ran Flow Force 640's and a DW200 pump with my NA16. A friend of mine is running ID1050's with his stock NA1.8. Mainly because he occasionally runs E85.

Is idle ve necessary? No, not necessary. A clean stable idle can be accomplished without it. It just gives extra resolution around the idle specific cells. I have mine setup for anywhere my idle would be with varying loads and with ac and all my lights on or every accessory off.
You can also use timing correction to get a more stable idle.

When my car was still running a 1.6 engine and stock 1.6 injectors in batch firing, I had good results using idle ve, idle advance set to 10 degrees at load of 25, 35, 45, and 55, and an idle rpm timing correction curve that was a little bit aggressive. The megasquirt will use timing correction in addition to the idle air control valve to keep a more consistent idle.

Something like this helped. I set my afr for idle at 14.5.


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Oh god idle air valve, that is a story for another day, have my ISC unplugged atm because I was getting wild behaviour with ms, not sure why. Just cranked my idle screw, it idles at about 1k rpm. For the time being it works and doesn't die on cold start, so Ill get to that eventually. A topic for another post.

Here is my updated table, I probably went overkill but I am really starting to like the looks of it. Also rebinned to get more granularity through the midrange. Plus really did not need 2 columns for idle.

Re: injectors, if I have trouble with VEAL / ve analyze ill swap em I guess, no e85 in the great white north.

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I run idle timing correction but not idle advance. If you are running a constant 10 degrees is it doing anything? At idle and below the benefit of increasing the advance plateaus at about 16-18deg. At -300 you would be at 28 and at -100rpm 20BTDC?

At the moment I am just running "idle valve type = None" with my idle valve unplugged. And my idle timing as specified in my ignition table a few posts above, it idles and doesn't die on cold start so sort of on the back burner for now.

Edit: oops didn't realise that was directed at andy

The idle advance is to overwrite the ignition table. If I am idling with my ac on, my kpa could be 50 and my rpm's could be 1050 or 1100. I want that to run 10 degrees. For tip in, If I am driving from a stop I want to not have 10 degrees at that rpm / kpa row because I am driving not trying to maintain a solid idle. The idle advance only happens when in closed loop pid idle. It works well.
Yup, it can ad that much timing. It corrects well and keeps for an even steadier rock solid idle. My radiator / fan setup is a single spal fan that is about 14 inches large. When the fan turns on the current inrush is enough that the car wants to stall. I think a typical stock fan current inrush is something like 10 to 15 amps. This one I think is in the range of 28 to 30 amps. On top of the separate fan settings kicking up the iacv, the timing correction adds more timing because the rpm's drop a bit. This all works together to help keep me at a solid idle.

At 600-700rpm, 100-200rpm dip I think 15 degrees will have a higher output then 25. Max cylinder pressure should occur at 18deg ATDC. I'm running two 12" spal fans with a total draw of 18amps. I had issues but have it handled with a more mild correction. Instead of running the idle advance I just have all of the cells in the idle area at 12 degrees. I guess its similiar I just went with this approach because it seemed less complicated.

Update: finalized my table and have been running veal for the last few days, seems to work pretty well and I have a half-decent ve table now. No audible knock via det cans using this ignition map that I stole from @Braineack on trubokitty.com.

One thing I have been struggling with is maintaining constant AFR at WOT, ill do a pull and it'll track 12.7-12.6 perfect, then ill hit the brakes do it again and it'll lean out and track 12.9-13.0, right after. Could this be a heat soak / MAT correction issue? Will post some clean logs once the weather gets un-rainy here.

TLDR: fuel map is getting decent, sometimes leans out at WOT

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