Any updates? I'm nearly ready to purchase my MS kit for My 20b.

 

i still have not gotten to the ECU phase of my build yet. I had planned it to go a lot quicker, but I have been working too much, and only have a few minutes a day to spare for the project. Even so, I should be hooking up the ECU within a week or two.

Pat

 

Thx! I need to make sure I order the right set-up.

 

i'm kinda regretting i didnt go with msII, because assembly isnt seeming very easy for me to learn, and C is really simple, so I could have actually made program changes way easier. Other than that, just v3.0 with some extra ign outputs looks like it will work fine.

 

honestly, even with the ms2 and C, you still have to know asm to do a good job. I've found that the compilers that are available screw up on a regular basis with simple math, and every time I write something that involves any sort of math, I have to look at the generated assembly anyway to make sure the compiler is doing what it should.

 

oh. well that sucks. anyway, it is looking like i am going to do leading + late leading only for right now. I am pretty sure that I can do that without any kind of code modification at all... long as i can figure out how to make it fire the coils (A,B, and C) twice

 

I plan on just running my NA 20b with no split. Like some of the others. Now I just need to make sure I get the correct kit.

 

hey muythai, do you have a recommendation as to where i should mount the #2 and 3 ignitors (vb921s)? Do they have to be on a heatsink like the built in one is, or can i just leave them hang?

 

The 921 must be heat sunk if you want them to live more than 30 seconds.

-Mike

 

I took a year off of the 20B project to catch up on everything else I put on hold. Now that I'm mostly caught up, I'd like to start thinking about the MegaSquirt again. Forgive me for being rusty.

patman, you asked about how to get the coils to fire twice? I found the way the MS works is injector events are variable but input triggers (from the CAS etc) and output sparks are 'hardwired' together.

Going from memory, I cut four teeth from the lower (24 tooth) wheel in the CAS to create four 6-1 sets of teeth instead of the usual two sets of 12-1 (where you only remove two teeth).

Inputing two complete 6-1 trigger cycles in the space of one 12-1 would normally cause the MS to think the engine is spinning twice as fast as it actually is. I can't recall what the tach in MegaTune displayed, but I know the car's stock 4cyl/2rotor tach read correctly.

Setting the MS to 12 cylinder mode corrected the injector events but I don't remember what it did to the tach. I'd assume it corrected the tach as well because injector events are akin to engine RPM, and setting it to V12 mode corrected the tach if I remember correctly (and I don't lol).

Anyway, are you starting to get the idea? I don't think I can explain it any better. All I know is modding the CAS for dual 6-1, setting the MS to V12 mode to correct the injector events also corrected the tach displayed in MT (I think), and the input triggers are connected to output triggers and can't be scaled, or at least I never found a way to do it.

By the way, my 20B only ran in warmup mode. After the fast idle solenoid would close, it wouldn't stay running. It could be driven in warmup mode though, and it wasn't exceedingly rough running or choppy.

An electrical glitch in the blinker sytem halted any fruther testing/tuning last year because it kept blowing fuses. I've since tracked down the problem and corrected it (the front turn signal 1156 bulb had fallen out of its base and the wires were shorting randomly).

 

your timing is pretty good, because i am just getting around to ignition right now. i am planning to hack into the cas tonite, if the boss (my gf) will give me time to do it. lol.

so what you are saying is that you cut 4 teeth out of the 24t wheel, and used a single VR sensor in the ms, and told it that it was a 6-1 wheel?

do you remember what tooth counts you set the coil firing locations to?

im still having a little trouble wrapping my brain around all this triggering stuff, but it looks like it might be a slow day at work, so maybe i'll get some study time.

thanks

pat

 

Basically, yes. The VR sensor was the stock one inside the CAS. The signal conditioner is actually the old stock Hitachi ignitor that came with the car. Man, I got lucky.Nope. I'll have to get back into MegaTune and check things out.I think I had to use a strange trigger angle as well. Or maybe trigger angle isn't what it's called. I can't remember.

 

This might be of help. You see here a 24 hour clock face. Each hour represents a tooth on the lower CAS wheel. If modifying your CAS the way I did, you want to remove a tooth at 00, 06, 12 and 18 (one every 90°). This will cause the MS to trigger on the next tooth I think.


To give myself a better understanding of what was going on in one revolution of the eccentric shaft, I drew some teeth on the outside edge of half the clock. I only used half because the CAS wheel spins half speed of the eccentric shaft, therefore only half the teeth will whiz by for every full rotation of the engine.


I started at the bottom of the clock face because the wheel spins counterclockwise. As you can see, L1 is the first tooth, then two teeth later is LL3 (late leading 3) at 60° of engine rotation or 30° of CAS wheel rotation, and at 120° we find L2 and so on.

It will probably look quite confusing at first but keep in mind the angles are offset by one tooth because the MS will not trigger a spark if there is no tooth present, like say at 0° (the bottom of the clock face).

If you were willing to start off using the same version of MegaTune and MSnS-Extra as me, it would be a simple matter of copying my msq etc to your setup. It all depends on whether you want to set your MS up the same way I did. My copies of MT and Extra are both over a year old.

By the way, it's been said that rotaries run best at Req_fuel of 10. Mine ran only in warmup mode at 4.1 and 5.5 in the greyed box. It didn't want to run at all after it would switch to normal mode. I don't know what this means exactly, but I suspect my req_fuel isn't high enough, or maybe my VE table is totally screwed up. Take a look. https://www.rx7club.com/forum/showpo...22&postcount=7

 

makes sense.

so i will use
L1=T1
L2=T5
L3=T3

and -35 trigger angle

I was too busy to touch the car yesterday, but tonite i will cut the cas and hopefully solder the ignitors into the MS, so very soon we will see how it works.

also i have all the timing advance and fuel maps from my 13b saved on my laptop, so if some of those numbers are what might have been causeing your warmup problem, i may have better luck

pat

 

I hooked up the MS to my computer and the trigger angle is 50°.

 

Could I take a look at your spark and fuel maps? If you could post them in picture format, that would be fine.

 

if i can find them and get them all compiled tonite, i'll post em up in the morning

the fuel maps will be way off for a 20b tho, and also they are in real units (injector pulse ms and degrees advance), not in ms lingo, since they are from my microtech
pat

 

degrees advance should be the same, and you can calculate a VE table based on the pulse widths in the microtech math since the MS's formula for calculating pulse-width from VE is freely available.

 

well unfortunately i got a little too pissed last night when my laptop wouldnt show any websites, and slammed it shut, so now i need a new LCD. and i dont have any way to get the maps.

however, some other people's microtech maps are posted here:
https://www.rx7club.com/microtech-111/tii-stock-base-maps-343297/

i cut the teeth on my cas last night, but after i trashed my $1100 laptop, i decided maybe it was time to take a night off, so i didnt get any further...

pat

 

update: still working out some bugs, and I am 200 miles from my car away at school now, but I did get it to run for a minute or two on saturday. hopefully my roommate and i will jump on the bikes wed. night and go down with a fixed megasquirt and have it running for real.

heres a couple pics i have laying around. cell phone quality and everything is pretty dirty, but shows you what ive got anyway

1st is current,
2nd is a good pic of the setup,
3rd pic is how much wiring i removed from the engine bay that was unnecessary

 

cool, glad to hear you got it running.