Alpha test: Miata/DSM 4G63 Optical CAS Dual Wheel

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md95
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Post by md95 »

No, the code will NOT sync if the CAS is rotated in the opposite direction. I tested that a long time ago on the bench. The main issue would be with the 2nd triggers(cam signals), as the 2 slots are of different length, and if rotated in the wrong direction, the code will see either the longer or shorter of the 2 slots first(not sure which one without looking).

I'm sure with a little tweaking of the 4/2 CAS decoder, it could be made to work in opposite rotation.
-Matt-
1998 Mitsubishi Eclipse RS 420A Turbo- MS2 Extra- 2.1.0 Release
1992 Plymouth Laser RS 4g63 AWD Turbo MS2 Extra- 3.0.3s
katok
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Post by katok »

katok wrote:hi all,
i have noticed that the 4/2 DSM CAS rotates counter-clockwise.
will it work if the rotation of the CAS will become clockwise?

i ask this because i have retrofitted my orig dizzy with 4/2 CAS.
and the rotation of the 4/2 CAS become clockwise.

will the CAS work if the rotation is reverse?


i have an idea regarding this issue. i'm thinking of opening the DSM CAS
and flip upsidedown the slotted disc of the cas

i guess it will work.

any comments on this?
6040solder
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Post by 6040solder »

6040solder wrote:the reason is that the two LED sensors in the unit are offset from each other radially. flipping the disk wont help either. you could have a new disk cut with the correct offset, but thats a lot of cost and time to spend on it IMO.
md95 wrote:No, the code will NOT sync if the CAS is rotated in the opposite direction. I tested that a long time ago on the bench. The main issue would be with the 2nd triggers(cam signals), as the 2 slots are of different length, and if rotated in the wrong direction, the code will see either the longer or shorter of the 2 slots first(not sure which one without looking).
^
katok
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Post by katok »

katok wrote:
katok wrote:hi all,
i have noticed that the 4/2 DSM CAS rotates counter-clockwise.
will it work if the rotation of the CAS will become clockwise?

i ask this because i have retrofitted my orig dizzy with 4/2 CAS.
and the rotation of the 4/2 CAS become clockwise.

will the CAS work if the rotation is reverse?


i have an idea regarding this issue. i'm thinking of opening the DSM CAS
and flip upsidedown the slotted disc of the cas

i guess it will work.

any comments on this?

i think flipping the sloted disc will work if the the slotted disc is reverse.

i don't have the STIM so I cannot test if my idea will work on the bench test

i guess i have to try and set-up it on the engine.

md95,
have you tried on the bench test flipping the disc and reverse the direction of the CAS?
6040solder
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Post by 6040solder »

Image

thats where the leds are. think about what that means with regards phase information if you reverse rotation, regardless of whether you flip it or not.

its a very different signal. whether that matters or not james or ken will have to answer.
md95
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Post by md95 »

This really depends on what you mean by flipping the disk. If you mean just turning over the disk top to bottom, then no, it wont work. IF you can modify the disk's center mount hole(since it's shape lets the disk mount only one way), to let you flip the disk from left to right, then rotated it in the opposite direction, it could work, at least theoretically. This would only hold true IF the LED sensors are NOT offset. I dont know if they are offset for a fact, but 6040 says they are. I've never looked into it. If the LED's are offset, then you would have to flip those as well to match it all up..I'd rather not mess up my test CAS disk to test it out though..it's the only one i've got at the moment.
-Matt-
1998 Mitsubishi Eclipse RS 420A Turbo- MS2 Extra- 2.1.0 Release
1992 Plymouth Laser RS 4g63 AWD Turbo MS2 Extra- 3.0.3s
6040solder
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Post by 6040solder »

Its difficult or impossible to separate the top half from the bottom without damage on the ones i've played with and destroyed. There is however a photo somewhere on this site or a mitsi or mazda or nissan site somewhere of the sensors insides. It IS possible that some are not offset, but i doubt it, least for the mitsi made ones (all the mitsi and mazda ones (that i've seen)).

Hope that helps :-)
md95
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Post by md95 »

6040solder wrote:Its difficult or impossible to separate the top half from the bottom without damage on the ones i've played with and destroyed. There is however a photo somewhere on this site or a mitsi or mazda or nissan site somewhere of the sensors insides. It IS possible that some are not offset, but i doubt it, least for the mitsi made ones (all the mitsi and mazda ones (that i've seen)).

Hope that helps :-)
So have you actually taken one apart, and seen that they are offset? Or are you going by a picture you saw? If you actually saw this with one you took apart, then that puts the idea to rest. I'd rather not destroy my only spare cas :) I'm pretty big into the DSM scene, so i can prob obtain another CAS, maybe one thats bad, to disect...as long as it's free anyway..

Katok- since you already have a stock 24-2 setup, you may as well use that..i think you are going in the wrong direction IMO. Keep it simple!
-Matt-
1998 Mitsubishi Eclipse RS 420A Turbo- MS2 Extra- 2.1.0 Release
1992 Plymouth Laser RS 4g63 AWD Turbo MS2 Extra- 3.0.3s
6040solder
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Post by 6040solder »

yes, physically seen and disected.

miata (seen it) :

Image

skyline (seen it) :

Image

dsm (havent seen it, but would place money on it) :

Image

mitsi v6 (havent seen it but would place money on it) :

Image

and another i cant find a pic of right now from a different mazda 4 cylinder that is the same also. i have disected them from 3 different engines and they have been identical and offset, which way they are offset i forget, but offset none the less.
md95
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Post by md95 »

It would make sense that the LED's are offset, as if they were on top of one another, an LED could false trigger from the other i suppose. This is the exact CAS i'm using on my car now- Was from a 1990 Talon 2.0 4g63 NT. I believe from 89-90 they used this CAS, then from 91-92 they used a CAS with a connector on it without the pigtail, then from 93-94 they used a "green top" cover CAS with a connector. This goes for the Mitsu 4g63 ones anyway.

Image
-Matt-
1998 Mitsubishi Eclipse RS 420A Turbo- MS2 Extra- 2.1.0 Release
1992 Plymouth Laser RS 4g63 AWD Turbo MS2 Extra- 3.0.3s
muythaibxr
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Post by muythaibxr »

Katok- since you already have a stock 24-2 setup, you may as well use that..i think you are going in the wrong direction IMO. Keep it simple!
I agree with that 100%!

Katok:

IF your car is already equipped with a supported configuration, there's no good reason to complicate things by switching to another configuration, especially one with less physical teeth.

Remember that the more teeth you have the more accurate timing will be during acceleration and deceleration.

with the 24 tooth (or even set up as a 12 tooth wheel) you'll have considerably better timing than with the wheel you're considering switching to.

Ken
6040solder
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Post by 6040solder »

6040solder wrote:katok, why not use the stock 24+2 denso dizzy for this?
:-) i agree.
katok
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Post by katok »

muythaibxr wrote:
Katok- since you already have a stock 24-2 setup, you may as well use that..i think you are going in the wrong direction IMO. Keep it simple!
I agree with that 100%!

Katok:

IF your car is already equipped with a supported configuration, there's no good reason to complicate things by switching to another configuration, especially one with less physical teeth.

Remember that the more teeth you have the more accurate timing will be during acceleration and deceleration.

with the 24 tooth (or even set up as a 12 tooth wheel) you'll have considerably better timing than with the wheel you're considering switching to.

Ken
thank you all for your suggestions.

All iI want to do is to run wasted spark only.
what is the best wheel to use , 24/2 or 12-1?
muythaibxr
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Post by muythaibxr »

It really doesn't matter.

I personally use the 24/2 setup on the rotary engine without any problems. Syncing on a low battery is easier with the 24/2 setup since the code isn't looking for any missing teeth.

Ken
katok
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Post by katok »

muythaibxr wrote:It really doesn't matter.

I personally use the 24/2 setup on the rotary engine without any problems. Syncing on a low battery is easier with the 24/2 setup since the code isn't looking for any missing teeth.

Ken
Ken,
Thank you for the suggestions.
I will try this 24/2 set-up, in this set-up i have to build additional signal conditioner for the 2nd input.
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