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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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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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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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. |
http://forum.miata.net/vb/attachment...chmentid=54465http://forum.miata.net/vb/attachment...chmentid=54466
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. |
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? |
Originally Posted by Joe Perez
(Post 184879)
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.
Originally Posted by Joe Perez
(Post 184879)
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.
Originally Posted by Joe Perez
(Post 184879)
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.
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.
Originally Posted by Ben
(Post 184881)
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.
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. |
Originally Posted by Ben
(Post 184881)
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.
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 :( |
Originally Posted by richyvrlimited
(Post 184986)
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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Originally Posted by AbeFM
(Post 184982)
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
Well codemonkey, looks like you've got some hacking to do. :D 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. 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. 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. 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?) http://flyinmiata.com/Store/images/07-91000.jpg And if I can develop a PnP solution then everyone benefits. The sensors are already there. |
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? |
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. |
Originally Posted by AbeFM
(Post 185117)
Ok, what's cmk and cpk and kfc and all that? Makes me hungry, the acronyms I know now what they are.
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. |
Originally Posted by AbeFM
(Post 185117)
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? http://www.msextra.com/ms2extra/MS2-Extra_Miata.htm |
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. |
Originally Posted by Matt Cramer
(Post 185252)
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 |
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. |
Originally Posted by AbeFM
(Post 185389)
, excepting that I'll be struggling for idle with my silly huge injectors.
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Official code docs: http://www.megamanual.com/ms2/code.htm
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Originally Posted by richyvrlimited
(Post 185649)
how big? I'm on 600cc's and can Idle fine (after a bit of work ;))
Originally Posted by JustinHoMi
(Post 185699)
Official code docs: http://www.megamanual.com/ms2/code.htm
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