Spark plug #64 on an 8 bit little endian system? Kudos!

But your motor doesnt have a turbo attached to it:

MX-5 Miata Forum - View Single Post - Question about Turbos

Haha.

I honestly debated with that. At work, all of our SSI stuff is big endian, however it winds up displaying as though it were little endian when viewed on a logic analyzer, so the end result is the same (read from left to right.)

On the other hand, most humans are accustomed to reading binary in big endian left-to-right when presented in print, and the clock on my shelf displays in this format as well.

I don't know if this is still relevant to the current direction of the thread, or if it is precise enough for your intentions, but here is a spark map that I put together to emulate the OBD2 computer's indications on my 1997 1.8L California car: https://www.miataturbo.net/attachmen...spark_rev2-png

More background on it can be found at the original thread: https://www.miataturbo.net/megasquir...=tuning+octane

/\ That's very interesting and still very relevant to this thread, thank you for posting.

What the heck is up with the -10 degrees of timing in the bottom left corner. The only time I've ever seen negative timing like that is when I was trying to get the formula car to idle below 4 grand with the shitty intake manifold that leaked like a sieve.

I don't think the car will even hit those areas at idle so probably doesn't matter?

it's just 10° After TDC. No biggie.

If we look at 750RPM (typical idle speed) and 10°BTDC (oem timing at idle), it takes 25° or 5.434ms for the flame front to reach 15°ATDC, or about 2mm into the downward stroke.

15°ATDC is an assumption of where the flame front is hitting for this comparison

Since that time never changes we can figure that within the latency of 5.434ms for the spark to ignite the flame and hit the piston since at 500RPM the crank rotates one degree in 0.33333333 milliseconds. At 500RPM 5.434ms is about 16° of crank rotation.

So if we spark at 10°ATDC, then the flame front has moved to ~26°ATDC. This should put the piston top maybe ~4mm into the downward stroke, so less power should be outputted at this time.I know I did this flame front math wrong, but you get the idea.

This is possibly an effort to stabilize the motor if the RPMs drop that low. If you advanced the timing when the RPMs dropped, it would increase the power and increase ultimately bump up the idle speed. I dont believe the stock ECU uses timing control like my MS3Pro to help control idle speed, so I'm assuming it's a way to allow the idle valve ot have greater effect at low rpms.

Very interesting. It's really becoming clear to me why everyone was able to get away with bumping the static timing by 5-10° (by rotating the CAS) and not have any problems, back in the day before enlightened ECUs.

Huge jump in timing from 1000-1200 rpm, 25-42 kPa. That is probably not the static table in the ECU, but observations made, with AC and idle compensation included. Such a static table will cause severe idle instability.

https://www.miataturbo.net/attachmen...1&d=1361998303

Jason is correct. The table was compiled/interpolated based on observations of OBD2 polling, and around idle there was some compensation done to stabilize things between A/C off (low load) and A/C on (heavy load), which is also why it is scaled somewhat non-uniformly so that I could isolate some key areas around idle and cruise.

The stock computer calculates spark based on rpm and MAF load (I believe) and possibly a few other factors. Since the MS is configured differently, this was my best interpretation at emulating it in effectiveness. When I was testing it out, the readings synced up quite well between MS and OBD2.

Note on the negative timing cells -- these cells were basically areas where the car was struggling to not stall. Braking to nearly 0mph with the transmission in gear and crawling along at low speed, high gear, throttle mashed open.

Joe,

What are you seeing as far as knock with your knock sensor? The following is my table that I have been tuning out knock peaks by lowering timing. Mine is much more conservative now that I have a knock module. I need to check my hardware latency as it is set to 21 microseconds.

https://www.miataturbo.net/attachmen...ine=1362504941

Knock sensor? Bah. A Jedi craves not such things.

Luddite :fawk: ;)

he has a 1.6
doesn't even have a knock sensor.
and he probably cares not about it enough to rig one up lol

luddite is right. drag your ms paint white pre-paste image to a tiny rectangle and THEN paste your graph. we dont' care about 3/4 of the content of that bs.

This is not the flame front you are looking for.

There you go bitches

Although the knock peaks are responding to reducing the timing. I'm wondering if I'm tuning out peaks that represent negligible knock. Unfortunately there are no clearly defined knock thresholds that we have to follow.

What hardware latency are others running on the ms3x?

You must learn the ways of the tune if you are to come with me to Thunderhill.

https://www.miataturbo.net/attachmen...ine=1362505409

Hey Joe P.

Thanks for the thread. It's given me the confidence to do two things:
1. Switch back to 87.
2. Run more timing

FWIW, I use Brain's map and added 5 degrees from 1660-7000 RPM and 24-98.7 kPa. It's still about 5 degrees less than yours though. The car's been running great so far.

Lee

are you n/a or turbo?

Unless he welded a turbo to his moss headers, I'm guessing N/A.

This sounds like something that needs to be done. :fael:

NA 1.6L.

FWIW, here's my spark map. I run an MSPNP with an MS2 and 3.3 alpha 10 code.

https://www.miataturbo.net/attachmen...ine=1363293620

I just thought I'd share some of the tuning work I've done this weekend. This should give some people a better idea of how WOT spark effects Tooutput as your approach MBT.
Test vehicle is a 99 miata mostly stock (4-2-1 JDM oem header, 2.5" exhaust)
ECU is MS3X, fuel tuned to 12.5 tapering to 12.2
91 octane gas used
Note: low compression in cylinder 4 and it was burning a decent amount of oil

I took the stock MSPNP pro basemap and tuned fuel first. I then did a series of runs at 7 degrees timing pulled from basemap, 5 deg pulled, 3 pulled, 1 pulled, basemap, 1 degree added.

DYNO was a mustang chassis dyno with WHP and WTQ output via analog signals to the spare analog inputs of the MS3X and logged.



I've charted the outputs below. The basemap seems to be pretty spot on MBT. The +1 deg gave a bit more power in some parts of the map but I'd call it just about no gain (MAT was lower for that run too).

I wish I ran a +2, +3, and +4 to see where WTQ drops off or where knock begins to happen. Maybe I'll rerun that another time.


https://cimg4.ibsrv.net/gimg/www.mia...f709cc7892.png

https://cimg3.ibsrv.net/gimg/www.mia...4d1fd7e412.png

https://cimg2.ibsrv.net/gimg/www.mia...4befc40c38.png

https://cimg0.ibsrv.net/gimg/www.mia...6629743f1c.png

https://cimg1.ibsrv.net/gimg/www.mia...6518c725d2.png
https://cimg5.ibsrv.net/gimg/www.mia...e80b4a8959.jpg

Looks good! This is a very accurate representation of what happens on sweep pulls if you pull timing with static fuel. The most common issue I see in tuning is the addition of fuel and timing for "more power" which, in effect, translates to a slower flame front during combustion from the additional fuel to compensate for the additional timing. All it nets is more fuel used. I'm not saying this is the case here but representing the most common issue I run see. To determine if your timing is optimized, you would choose to make fueling alterations at a given timing point. If you are able to hold a load point on an eddy current or similar dyno, you can make these changes real-time.

Pretty cool, thanks for sharing, and yeah there's not really even a point in playing with timing much past base map on 91. 27-28* unless you have major breathing mods

in MS usually the addition of timing necessitates the addition of fuel (if you're really making more power) as the car will lean out otherwise.

Why is this not a sticky? Lots of good info in here. I need to play with my spark map some.

we have lots of threads that should be stickied. its easier to just berate the n00bs when they ask :D

I am referring to the cyclic loop many tuners enter when they simply target more timing to make more power, then end up adding fuel to keep knock under control. Typically, it is possible to dial back fuel and timing in such cases and make the same power. The trick is dialing both back though as playing with just one variable at a time will register lower power. Many articles written about it and tuning guidelines regarding it. Here is one Spark Timing Myths Debunked - Spark Timing Myths Explained:: Application Notes .

The other, even more common, issue I see is people adding fuel when they are seeing a wideband read lean due to rich misfires.

throwing fuel at det is doin it wrong.
that wasn't part of this convo which is why I was curious why you brought it up.

https://cimg1.ibsrv.net/gimg/www.mia...a3417292bc.jpg


advancing timing only

You can't be sure unless you also change fuel parameters. He kept them fixed. A full dial in will involve optimizing fuel & ignition. This adds a lot more time to the tuning process and thus money as well. He could end up making more power at -1 deg while targeting 12.9:1 across the range, while saving fuel assuming this is NA. Or he could get nothing and he just happens to be optimized currently using rule of thumb fuel data.

I'm very glad this thread got back from the dead. Have been playing with cruise cells on my friends turbo 1.6 and was really apprehensive about going any further, after referencing other maps.
Learned a lot of good things influenced by this thread. Definitely deserves a sticky.
(Network down at work today, spent the last 9 hours "researching")

Hi, I am trying to find someone with a 1.8 Turbo with matching black top injectors that I can compare my tables with. I have not driven much yet as I am still working out all the settings. I have used the warmup tuner and ve tuner. i know most of things to configured and have done so but timing is everything :) I know there a a few maps posted here but many are for NA or 1.6.

94 MX-3
BPT import
MicroSquirt
LS2 Coils Batch Fire

Hey is anyone still running these maps? Have you made any modifications? Still running 87 octane? Thanks!!