MS1 losing CAS signal
 

MS1 3.0
(spec in sig)
29y4


So when driving, both in boost and cruising, tooth logger will show the signal disappear randomly, at the same time the tach drops and the car pops
ive went throw timing/dwell/injector pwm/diff cas

any ideas?

EDIT
now on HiRes 10g, with 330ohm resistors, and .1uf cap

This seems to be a common issue around here due to the unreliable CAS we have in these cars. I've spent lots of time trying to correct this issue myself and have yet to be successful, although I have been able to make it happen less ofter by running dedicated grounds and adjusting the timing belt for less slop. The only real cure seems to be to ditch the cas and run some form of Crankshaft trigger instead.

This is not a common issue, and we have very reliable CAS units...there's nothing to them.


they can start to degade considering they are pushing 23years old...so you just get a new used one, and go one with life...no need to upgrade to a crankshaft trigger.

Im going off of what I've read in posts made by joe perez. I've tried 3 different cas units all with the same effect. Rather than spending money on additional Cas units it just seems more worthwhile in my opinion to upgrade to a crank trigger, especially considereing there is an OE 36-1 trigger wheel that can be had from a junkyard for next to nothing.

then I blame shotty wiring.

It very well may be considering the wiring is now about 23 years old, but I've exhausted my efforts on this issue short of running all new shielded wiring from the cas to megasquirt. Funny thing is it could drop out 100 times on the highway I'll shut the car off and turn it back on and it wont do it again until the next restart.

that's odd a hell.

mine will keep doing it

you could try using the VR circuit for the crank trigger and opto circuit for the cam trigger...see if that improves the signal. but I've never heard of or had tihs issue with the hundred of MSs I've built.

now i did get the ms unit from a member on here, and it is ran parallel to the stock ecu
might that effect it?

1 more thing, the p/o of the car had a safcII in the car, very crappy job of wiring it in too, could one of the wires the safc feeds off of be the culprit?
i think the safc wires are power/map in/map out/tps/tach/ground/ground/o2
now, i dont have a stock o2 anymore either, i eliminated it, my powerdex feeds the MS (did same thing with my AEM ugo)

no, i ran parallel for years to no ill effects; never lost the CAS signal.

but sometimes the spark gap and spark output method could cause oddities and blowout. running boost and stock coils?

but yeah, shotty wiring like i said could be some issue...but I'd look into the CAS and ground wires if anything

alright will do.
ill try adding a ground directly to the CAS and run it down by the ecu first. heck, i got cat6 here, if anything, i can build me a jumper harness from the cas to the ecu and see if that fixes it, if it does ill just rewire the car, i want to eliminate the stock ecu anyway

its possible the harness has fatigued. I've had the actually pins snap off, where the solder held fine. they appeared to be fine, but you could feel the connection felt "loose." wiggling it just a bit and the pin snaps...those connections in the meantime are not solid and intermittent.

im still wondering if its the way the ecu is setup
i got it off Devin, kingof133t made it. the MS ecu is wired into the stock ecu, 2 toggle switches that switch between stock fuel to ms fuel, and stock spark to ms spark
i attempted to eliminate to just the MS, when i found that the resisters for the ignition out are in the stock ecu case with the toggle switch

no prongs on the stock ecu are cut, so im wondering if the stock ecu is messing up the signal

He didn't use the most ideal spark outputs, IIRC, they caused havok. I remember running them and always having the singals cut out in boost around 6K or something.

If you can post pics of the board and your msq we can see.

well here is the msq, ill get pics a little bit later when i make it outside

i dont have MS installed in the machine. is your spark output set to normal or inverted?

inverted

https://www.miataturbo.net/attachmen...ine=1338921254
https://www.miataturbo.net/attachmen...ine=1338921254

i care more about the ECU (ms) side of things...but god i hated how he did this.

the orange wire i added for launch control

https://www.miataturbo.net/attachmen...ine=1338922580
https://www.miataturbo.net/attachmen...ine=1338922580

yeah, you need to move the blue and green wires and add a 100-300ohm reistors on each as such:


Green wires:
https://www.miataturbo.net/attachmen...ine=1338923846

then youll use NON INVERTED for the spark output method. should see the dropouts go away, luckily your ignitor is still healthy.


you can probably go ahead and add that capacitor and remove c30 as well.

i just slide the housings off the green and blue wires, they have a 330ohm resistor on each, would that be to much to reuse?
O O B G

yeah but they arent going to the right spot and they aren't pullu p resistors, they are inline so far as i can tell.


look at the diagram i posted and compare how they go into the board (led side only)

i can solder them in if needed be. i dont have the money to order anything lol
https://www.miataturbo.net/attachmen...ine=1338927059

do this and change the spark setting. in the least this will solve the issue...well more than likely.

https://www.miataturbo.net/attachmen...1&d=1338928589

hows this?
https://www.miataturbo.net/attachmen...ine=1338929124

should i eliminate these? im not sure what they are for
https://www.miataturbo.net/attachmen...ine=1338929504

no just try what i said.

now it wont start, just cranks

Its missing r24 and r26 isn't it?

Yeah in the top pic of the board...see the two missing resisotrs by the leds? You need those. 1k iircc

26 and 29 is missing, 24 is still there

Yeah that. You'll need them. You can steal from elsewhere on the board on sec and ill figure it out

EDIT: sorry was on phone. steal from r42 and r55, they are next to each other, center of the board. put them in r26 and r29.

ok just did that, going to go out here and try it

one question, i noticed on the diagram you have above, it shows there should be a 1k resistor between iac1a and js8 for tach, then 470 for iac1a to another spot
if you look at my pic, look at my brown wire for tach, its missing the 1k, and it had another resistor running from the js8 to another hole across from it, not where shown in the diagram

still no start

maybe you need to revert ( just lift one leg of r44 and r52 back up, you dont need to replace them back), but that should have done it.

you said 42 and 55 last time, so pull 1 leg on 44 and 52?

it was 42 and 55, you moved them to 26 and 29 correct?

sorry, im on my phone and going from my poor memory when im replying.

yea they are on 26 and 29 now, car didnt start before moving them, or after

if it makes any different, the tach isnt moving any of the attempts yet

dash tach or megasquirt digital tach?

those first two resistors you moved? they are orange orange red gold?

dash
the 2 you had me move are brown black red gold

no, the first that were already on the green wires. i think they are 30K or something judging by the colors which may be why the dash tach isn't moving (no spark)

oobg, 330ohm

hmmm i dunno then. i guess revert it all back and ill scratch my head for a bit.

well, i left it as it was last night, and rebuilt the harness for standalone, and it starts now! it does POP when you first turn the key on though, scared the ---- out of me lol
still working on it of course, IAC works, i dont know if the fan does yet

search about the pop. that good, wonder what the deal was, but that dropout SHOULD go away.

i spent hours last night building the harness from scratch lol
someone should really label the parts each wire goes to from this
https://www.miataturbo.net/attachmen...ine=1339004450
and i say that because there is 2 Bl/w and 2 Gn/w, one of each has a yellow line, which i presumed to be the sensor one, however, since i was making it from scratch i was guessing lol
http://www.boostedmiata.com/gallery2...ne_harness.jpg

thats why those pin positions are called out on the oem side diagram. make sure your clutch input and fan output match...

my clutch switch is bypassed so i didnt hook that up
it doesnt specify which is which, unless im looking in the wrong places

the colors with yellow highlight i used for the ignitor and CAS, car runs so i assume i assumed right lol
so the 2 without yellow are for clutch and fans? i didnt solder those 2 to the harness connector yet, just the db37.
i dont have the fan mod installed, granted i dont have the IAC either, though IAC works.
presuming my fan doesnt work, what part numbers will i need? i have a couple old ecus from other cars i robbed a 1k 1/4 off of last night, along with a few other parts. only thing i dont have is the .01uf cap

correct.

(but look again on the harness diagram--the blue/green CAS input is label with pin 25, and the spark output is labeled with pin 31)


you can use the middle led circuit to run the fan relay...see the diagram i posted a bunch of posted back.

wow, i see that now lol, i feel stupid now :facepalm:

not sure how i missed that lol. yea im looking at the diagram now, about jumping d15 led, so im reading through that. you say q4 is not used so put the q4 chip where the q7 chip is/was?

btw, heres my final
https://www.miataturbo.net/attachmen...ine=1339008791
https://www.miataturbo.net/attachmen...ine=1339008791

back to the drawing boards, fixed the shock earlier, finally got to road test it, its 20x worse now

video
https://www.miataturbo.net/attachmen...ine=1339335331

where are you at Braineack?

bypassed CKP and CMP to the ecu, still dropping off, so it has to be something with the ecu physical setup

added a .1uf cap, still same results

and ideas? im completely lost, if it were not for the bike i would be stranded at home

you know a lot of times when you see RPM spikes like that it's a bad ignitor...


that's what mine was doing after a while of running on those old kingofleet mods.

under wheel decoder options, try:

base = 2
2nsd trigger
rising
no missing
trig pos A 2
Trig pos B 1

025 style

the ignitor is built into the coils correct? so if i change the coil pack in theory it should go away