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Old 12-12-2007, 01:08 PM   #21
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I don't understand the reluctance to add an NA CAS to the NB. Seems to me to be a simple, effective, and proven solution, without real downside. Only negative I can think of is the cost of the part, which is negligible if purchased used.
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Old 12-12-2007, 01:10 PM   #22
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Adding a CAS to an NB isn't that bad, it is a working solution. It would be nice to be able to make a full on PNP solution for the NB though. If something could be built and contained within the MS case that would be awesome.
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Old 12-12-2007, 01:17 PM   #23
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I understand that from a PNP level, but someone who assembles their own ecu and flashes it with their own code ain't exactly a PNP customer.
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Old 12-12-2007, 01:31 PM   #24
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I'm not talking about adding an NA CAS to an NB, I'm talking about using the one that's already there. In the '00 anyway (the latest year for which I have a diagram) you guys have a factory camshaft sensor, separate from the crank sensor, feeding position 2H on the ECU via a GY/L wire. From the diagram on page B-1b of the FSM, it appears to be near the front of the engine on the cold side.

If this sensor produces a single pulse per cam rev (one pulse for every two crank revs) then it could be used to drive a simple gating circuit that would steer the EM's injector pulses to two separate injector banks.

(thinks about this for a minute...)

No, actually there's a problem with this idea- you couldn't go above 50% duty cycle on the injectors at any time. Bad idea.
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Old 12-12-2007, 01:43 PM   #25
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I know what you're talking about Joe. Top right is the 2002 cam signal. The others are from an NA.
Here's a thread that was started concerning this.
http://forum.miata.net/vb/showthread.php?t=259190
Reverant is currently building a custom circuit for it, not sure what it entails.
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Old 12-12-2007, 01:55 PM   #26
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Ok, the top picture looks like an NA CAS to me. Upper trace is CMP, lower trace is CKP.

The bottom picture is an NB, I assume? I can't quite figure that one out. I thought that the NB crank wheel had four teeth on it, evenly spaced. Neither of the two traces seems to indicate that. Could you translate that picture for me? Which trace is which, and what's up with the double-single-double-single upper trace?
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Old 12-12-2007, 04:39 PM   #27
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Nay. Look at the schematic here: http://www.jbperf.com/p&h_board/P&H_board_schem.jpg

It's four completely separate driver channels. Output INJ1 is driven by U1, which is triggered by input 1. Output INJ2 is driven by U2, triggered by input 2, and etc... There is no switching logic at all, this board is just a simple input follower.
Totally. I wasn't suggesting to use any logic on that board. I was saying if the MS has basically 4 channels, two for gating and two for PWM, you should be able to use those four channels all for gating and use a follower board like that for $15 to keep the injectors happy - and have true sequential injection.

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A thought however- I don't know what the cam sensor on an NB outputs. If you guys get one pulse per cam revolution (indicating #1 TDC only) instead of two pulses per cam revolution like us NA'ers, then it would be trivial to build a circuit to steer the pulses from the MS to the correct pair of injector drivers, based on the CAS indication.
It's got a single pulse on one side, and a double pulse on the other. I beleive it's the turning off of the first pulse each time that corresponds to TDC for cyl 1/4. There are also four blips on the crank, TDC/BCD, but then the other pulses (apparently!) aren't evenly spaced something about 170*/30* or something strange. I remember reading all about it in a nice thread with GREAT pictures of the traces..... and I can't find it. I can only assume it's on the thread Arga was running on the MS-x boards.

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BTW- what EGT sensor are you guys using? Mine is slower than hell, no possible way it could be used for fuel tuning- if I floor it on the highway, it takes a couple of seconds to see the change in EGT.
Bit off topic, but.. :-) I got mine from a place my burry has been using for years, says they are really good. I was using one from Westach, kinda pricey. The place I just got it from ($55 shipped) was
http://www.teamrip.com/accessories.html
And they claim 0.180 seconds/100* f. Not quick, not slow. I keep getting tempted to try to mount a BARE sensor in there, but I'm sure it would only last like a day.

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I don't understand the reluctance to add an NA CAS to the NB. Seems to me to be a simple, effective, and proven solution, without real downside. Only negative I can think of is the cost of the part, which is negligible if purchased used.
Yeah - I dunno, it just doesn't seem "right" to me. And if I can develop a PnP solution then everyone benefits. The sensors are already there.

And adding anything to the back of the motor could only make getting the coil packs on and off even harder. :-) Oh, and the weight. :-P But mostly, I just want to do it. It seems clean and trick. I really want to run a 32-1 toothed wheel or something, actually. Seems like you could tell more about the motor that way.
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Old 12-12-2007, 04:45 PM   #28
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I don't understand the reluctance to add an NA CAS to the NB. Seems to me to be a simple, effective, and proven solution, without real downside. Only negative I can think of is the cost of the part, which is negligible if purchased used.
the advantage of the NB hardware is it's more accurate.

Hypothetically if the MS could utilise the NB hardware I'd have moved over to it by now for that very reason.

Not because my car runs poorly, etc. just because if something is more accurate it'll improve the driveability/smoothness of the car (even if it's only 1% it's worth it to me)

I just wish I was clever enough to be able to beta-test the NB code for the MSII :( as it is I'm going to move over to the MSII chip and then port over to the NB hardware once someone else far cleverer than me has done the legwork :(
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Old 12-12-2007, 04:53 PM   #29
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I just wish I was clever enough to be able to beta-test the NB code for the MSII :( as it is I'm going to move over to the MSII chip and then port over to the NB hardware once someone else far cleverer than me has done the legwork :(
I'm following in Arga's brave footsteps there. :-) I still think for best accuracy, a many-toothed crank wheel is the way to go, and that's already well understood.
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Old 12-12-2007, 05:04 PM   #30
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I was saying if the MS has basically 4 channels, two for gating and two for PWM, you should be able to use those four channels all for gating
Gotcha. Use PWM0-1 and PWM1-1 as the first and second injector channels (as is done presently) and hijack the fb_inj1 and fb_inj2 signals to drive channels 3 and 4.

Well codemonkey, looks like you've got some hacking to do.

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It's got a single pulse on one side, and a double pulse on the other. I beleive it's the turning off of the first pulse each time that corresponds to TDC for cyl 1/4.
Ok, that makes sense. Whereas the NA has one long and one short CMP signal, the NB has a single pulse and double pulse CMP signal.

You know, you could in theory extract a single "true #1 TDC" out of that by using a two bit counter which is reset by CKP. IOW- once two CMP pulses are received, generate a surrogate CMP pulse. But reset the counter on each CKP pulse. So only the double-pulse would be able to generate an output pulse. You'd just have to offset it somewhat as we'd be looking at the rising edge of the second pulse vs. the falling edge of the first.


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There are also four blips on the crank, TDC/BCD, but then the other pulses (apparently!) aren't evenly spaced something about 170*/30* or something strange.
This is where I'm getting confused. The bottom trace on the second pic that cjernigan posted only has a single crank event on it, but the cam pulses indicate that two complete cycles (four crank revs) are shown. WTF?

The sum total of my knowledge about the NB crank wheel comes from a single picture posted on FM's site about their adjustable crank wheel. And now that I look at it, you're right- those teeth aren't evenly spaced. (Why did I think they were?)




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And if I can develop a PnP solution then everyone benefits. The sensors are already there.
Well, consider the CMP counter idea. I relinquish all rights to the concept to you.
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Old 12-12-2007, 09:35 PM   #31
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I still can barely believe they aren't evenly spaced, but they aren't.

Ok, what's cmk and cpk and kfc and all that? Makes me hungry, the acronyms I know now what they are.

Really, just get the computer to read them (similar set up on DSM's) and run with it, no reason to build circuits, is there?
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Old 12-12-2007, 10:13 PM   #32
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first part of this thread discusses it:
http://www.msextra.com/viewtopic.php?t=24249

one cam pulse, 4 crank pulses, 2 cam pulses, 4 crank pulses.

8 crank pulses in a 720 degree crank cycle. (360 cam cycle)

Crank pulses 2, 4, 6, and 8 occur 10 degrees BTDC and work nicely as tach pulses.
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Old 12-12-2007, 10:25 PM   #33
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Ok, what's cmk and cpk and kfc and all that? Makes me hungry, the acronyms I know now what they are.
Those are Mazda's abbreviations for the various signals, at least on an NA.

CMP = Cam Pulse. One per crank rev- a long one and a short one. (I haven't scoped 'em out yet to tell which is which.)

CKP = Crank pulse. Two per crank rev, evenly spaced at 0 and 180, all of equal length.

KFC = Kentucky Fried Chicken. A lump of steroid-enhanced poultry, deep fried under pressure and seasoned with a blend of 11 herbs and spices.
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Old 12-13-2007, 09:11 AM   #34
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I still can barely believe they aren't evenly spaced, but they aren't.

Ok, what's cmk and cpk and kfc and all that? Makes me hungry, the acronyms I know now what they are.

Really, just get the computer to read them (similar set up on DSM's) and run with it, no reason to build circuits, is there?
You might want to take a look at what the MS2/Extra crew has been up to, although it's a work in progress and the sensor pictures are not completely accurate.

http://www.msextra.com/ms2extra/MS2-Extra_Miata.htm
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Old 12-13-2007, 02:45 PM   #35
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I've been starting to, and thanks for the pointers.

I'm hoping the jimstim (maybe in 4G63 mode?) will do a good job emulating my stock sensors. If that's working, I figure everything else should just work out, excepting that I'll be struggling for idle with my silly huge injectors.
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Old 12-13-2007, 10:01 PM   #36
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You might want to take a look at what the MS2/Extra crew has been up to, although it's a work in progress and the sensor pictures are not completely accurate.

http://www.msextra.com/ms2extra/MS2-Extra_Miata.htm
The Cam Pulse circuit is much more complex that what I have. (Probably for protection.) I had seen awhile back that they were using the VR circuit rather than the Hall but assumed it was a mistake. Looks like they mean it. Not a really big deal for the crank signal because it's already on the PCB but I don't think the cam circuit will even fit on the proto section especially once you add in injector output circuits.
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Old 12-13-2007, 10:24 PM   #37
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It did look way complicated. Yours works, though, right? I wonder if it could be leading to your missing pulses?

How many "chugs" does it take to start?
-Abe.
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Old 12-14-2007, 05:39 AM   #38
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, excepting that I'll be struggling for idle with my silly huge injectors.
how big? I'm on 600cc's and can Idle fine (after a bit of work )
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Old 12-14-2007, 11:26 AM   #39
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Old 12-14-2007, 01:21 PM   #40
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how big? I'm on 600cc's and can Idle fine (after a bit of work )
650cc's. Yep, just that tinsy bit bigger even than a tinsy bit bigger. In fact, the guy I got them from sold them since his 'tuner' couldn't get an idle. :-P But, I gotz mad n00b skillz

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I put the ms2x code on last night. Still building the ins-and-outs, but it was at least talking which was nice! I put on the 11-22 beta since Arga's been getting his car running on that with OEM sensors. Plus, the bigger the build number the larger your..... source code. ;-)
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