DIYautotune's CAS replacement wheel - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 12-21-2011, 07:53 PM   #21
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Quote:
Originally Posted by richyvrlimited View Post
360 teeth will just waste processor cycles reading them all, pointless.
^This.

The MS2 might be able to handle it, but with a 360 tooth wheel, the poor little MS1 would probably crash. At high RPMs, I doubt it would even be able to handle the primary interrupts fast enough, much less actually run the engine. For comparison, an engine with a 360t wheel running at 7,000 RPM would put as much interrupt workload on the CPU as an engine with a EDIS-style wheel (36-1) running at 72,000 RPM.


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The TEC lineup as one of the most accurate ignition systems available and it only uses 60 teeth, tell me why more would help?
More to the point, a 360t wheel mounted on the end of the camshaft will still have more steady-state scatter as a two-tooth wheel mounted to the crankshaft.
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Old 12-22-2011, 05:43 AM   #22
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Much more eloquently put than me as usual Joe

Nice maths too BTW, puts it into perspective how much load a 360 tooth wheel would put on an ECU, 72,000 rpm!!
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Old 12-22-2011, 10:06 AM   #23
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Nissan used dedicated hardware to handle the 360 slit ring. Neither the MS1 nor the MS2 can really use that set of slits properly unless someone tried to clone the external counter circuit Nissan used and write code to make it work.

The MS3 is a different case - it's possible to program the X-gate to take the place of the stuff Nissan used to run this wheel.
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Old 12-22-2011, 01:08 PM   #24
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Quote:
Originally Posted by Joe Perez View Post
More to the point, a 360t wheel mounted on the end of the camshaft will still have more steady-state scatter as a two-tooth wheel mounted to the crankshaft.
Maybe if you held RPM steady. With rapidly changing RPM, the higher tooth count wheel would be better (assuming (1)your processor is up to the task. so far, the MS3 is doing well with 360 tooth testing; (2) you don't have an abnormal level of slop in your timing gear).
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Old 12-22-2011, 02:51 PM   #25
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Quote:
Originally Posted by Ben View Post
Maybe if you held RPM steady. With rapidly changing RPM, the higher tooth count wheel would be better (assuming (1)your processor is up to the task. so far, the MS3 is doing well with 360 tooth testing; (2) you don't have an abnormal level of slop in your timing gear).
Agreed, assuming that the ECU in question is capable of predictive estimation to select the tooth most appropriate to start the timer (MS2/3), which is why I called for "steady state". And even at this, you're only compensating for spark drift based on error in the timer setting relative to acceleration of the crankshaft. This drift, while undesirable, is at least predictable and can be compensated for in dyno tuning, assuming that one is tuning with an inertial dyno rather than a steady-state dyno.

Any slop in the cam belt system as a whole (which I measured at nearly +/-5 steady-state in my engine with a new timing belt) will remain unaffected. Ergo, periods of low delta-RPM and high load (eg: boost in 4th or 5th gear) will suffer from equivalent scatter regardless of toothcount.
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Old 12-24-2011, 01:06 PM   #26
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Old 12-24-2011, 05:02 PM   #27
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Is there a 1.6 bolt-on 36-1 cranck wheel available?
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Old 12-24-2011, 06:30 PM   #28
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Originally Posted by IHI View Post
Is there a 1.6 bolt-on 36-1 cranck wheel available?
There is at least one that I am aware of. Took a while to fabricate, and it's currently installed on a '92 somewhere up in Michigan.
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Old 01-09-2012, 05:04 PM   #29
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Success, ms2extra running my 1.6 miata motor with the diyautotune cas shutter wheel.
Tested in both batch inner ring and with the outer and inner ring. Working on both. Spark scatter is a lot less now at idle.
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Old 01-09-2012, 05:20 PM   #30
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Quote:
Originally Posted by IHI View Post
Is there a 1.6 bolt-on 36-1 cranck wheel available?
If it fits on the front of the crank there is no way in hell it will fit with AWR swaybar mounts.
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DIYautotune's CAS replacement wheel-themoreyouknow.jpg  
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Old 01-09-2012, 05:53 PM   #31
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Quote:
Originally Posted by Techsalvager View Post
Success, ms2extra running my 1.6 miata motor with the diyautotune cas shutter wheel.
Tested in both batch inner ring and with the outer and inner ring. Working on both. Spark scatter is a lot less now at idle.
Good to know! You mentioned in your other post that is seems to be way thinner than the factory one. Did you have any problems with that?
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Old 01-09-2012, 09:21 PM   #32
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Good to know! You mentioned in your other post that is seems to be way thinner than the factory one. Did you have any problems with that?
I'm not sure why its so think, my guess is for laser cutting it out. It being so thin makes it very flimsy compared to the stock disc. you can easily bend it in different ways where the stock one you couldn't bend it without getting it stuck in the shape you bent it to. Also since its so thing it likes to bow instead of stay flat which leads to it rubbing aganist the black plastic of the sensor pickup housing in the CAS.

It maybe the material as well, I didn't check if it was metal or alu but if a tad thicker wheel keeps it from bending like it does I would suggest diy to go for it if costs don't go up drasticly as well if it can still be laser cut.
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Old 01-10-2012, 01:45 PM   #33
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is there a link to the diyautotune CAS wheel? I couldnt find it on their site.
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Old 01-10-2012, 01:49 PM   #34
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Originally Posted by tottestad View Post
is there a link to the diyautotune CAS wheel? I couldnt find it on their site.
http://www.diyautotune.com/catalog/o...4de-p-472.html
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Old 01-10-2012, 03:03 PM   #35
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thank you
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Old 01-10-2012, 03:49 PM   #36
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1.6 93=< do drive the tach of the coils but having a different cam\crank setup has no bearing on the output of tach signal.
And if you do convert to seq spark you would have to get tach input from a different source as you would change out your coils as well more than likely.

on the 1.8s I don't know wheres its driven from.

and yes cut off one if you want the TSE 12 tooth to be a 12-1

Besides that if you are going to convert to this new wheel I take it you are running a standalone so you might want to consult with the manual and see if it can output a tach signal
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Old 01-10-2012, 04:02 PM   #37
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1.8 is driven from 2 sources depending on year.

Up to 1995.5 it's driven from the coils, post that'd date the ECU drives the tacho
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Old 01-10-2012, 04:48 PM   #38
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Anyways going back to the thread I used first 345 tigger offset to get my engine to fire up. No go just loud back fires. Read up something so I started advancing timing got to 200 where it fired and ran like a weed wacker. Finally end up at 135 trigger offset with 18 degrees of timing at idle.
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Old 01-10-2012, 04:51 PM   #39
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Quote:
Originally Posted by Ben View Post
Haven't we discussed this at least twice previously?
Just once, but apparently I didn't put two and two together.
Quote:
Originally Posted by Ben View Post
You can't use the 12 tooth wheel with stock NB cam trigger if you plan to run VVT or sequential.
I don't understand why. Why am I required to run a 12-1 CKP if I have a single-tooth CMP? It seems logical to me that I can use a single tooth CMP to indicate position.
Quote:
Originally Posted by Ben View Post
The MS2 / MS3 NB Miata wheel decoder is looking for stock trigger wheels.
Why not run the 12-tooth wheel for less scatter?
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Originally Posted by Ben View Post
If you run the 12-1 on the crank, you will need a 1 tooth wheel on the intake cam for closed loop VVT and sequential.
Got it.
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Originally Posted by Ben View Post
90-93 tach is driven by ignitor.
94 to early 95 driven by coils.
95.5 + ECU
MegaSquirt can run tach on any NA or NB in place of whatever generated the factory signal.
Thanks.

Last edited by hustler; 01-10-2012 at 05:11 PM.
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Old 01-10-2012, 05:11 PM   #40
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I'm going to make a seperate thread for my problems, I can't be the only one who's this dense...well, maybe I can.
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