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Old 01-06-2009, 10:24 AM   #1
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Default Cam Sensor Output image wanted

Have searched the posts but only found one dead link. Looking for an image of the signal output from the Cam Sensor for the 90-93 optical and 94-95 reluctor USA model engines.
Images of the internals of these would be usful as well.
Thanks.
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Old 01-06-2009, 10:31 AM   #2
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Joe Perez has posted it a few times...
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Old 01-06-2009, 10:34 AM   #3
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I'll search again,, better key word???
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Old 01-06-2009, 11:27 AM   #4
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Here are the scope traces: https://www.miataturbo.net/forum/t29726/

The hand-drawn one is my observations of the hall-effect CAS in my '92. (Not all 1.6's had the optical sensors, apparently.) Later, there's a proper scope capture I took of the 4G63 simulation mode of the JimStim.

From an electrical standpoint, both of the CASs (Hall and optical) are identical. They both have open-collector outputs, and they both produce the same waveform.


Here's the innards on the optical unit:





And the hall-effect unit:


(source for both images: Miata Fuel and Engine Electronic systems interchange Guide)


And here is a rabbit with a pancake on its head:





So, what are you up to?
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Old 01-07-2009, 12:49 PM   #5
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Does the extra capacitance of the pancake affect the rabbit's response time?
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Old 01-08-2009, 03:39 AM   #6
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Thanks so much for the great info and pictures. I am going to make a new optical disk (4:1) so I can run sequentially to get every last drop from the stock injectors before lock up. The reluctor unit is easy just cut off one of the inside tabs. This is for a stand alone ECU to be used in a Spec racing series. Couldn't find my camara and needed to email some pics of the above. Thanks again.

With Batch fire and 12.5 AFR target, got 150 RWHP on stock injectors @6.8PSI (Manifold).

So you say the signal output is the same? Thought you needed a 5v pullup resistor for the Hall inputs to generate a voltage.
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Old 01-08-2009, 08:29 AM   #7
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Quote:
Originally Posted by drgoodwrench View Post
Thanks so much for the great info and pictures. I am going to make a new optical disk (4:1) so I can run sequentially to get every last drop from the stock injectors before lock up. The reluctor unit is easy just cut off one of the inside tabs. This is for a stand alone ECU to be used in a Spec racing series. Couldn't find my camara and needed to email some pics of the above. Thanks again.

With Batch fire and 12.5 AFR target, got 150 RWHP on stock injectors @6.8PSI (Manifold).

So you say the signal output is the same? Thought you needed a 5v pullup resistor for the Hall inputs to generate a voltage.
Just get an escort gt distributor. Same thing as the miata cas but they're 4:1.
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Old 01-08-2009, 12:25 PM   #8
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Quote:
Originally Posted by drgoodwrench View Post
So you say the signal output is the same? Thought you needed a 5v pullup resistor for the Hall inputs to generate a voltage.
What did I just say earlier?
Quote:
Originally Posted by me
They both have open-collector outputs
You need a pullup resistor to use either one. Within the Miata environment, the two sensors are completely interchangeable. You can run with the Hall sensor or the Opto sensor with any ECU from '90-'97. All the ECUs have pullups, and all the CAS's have open-collector outputs. In fact, my '92 had a hall sensor on it when I bought it. No idea if that was factory or if the OP changed it. It's gone now, so it no longer concerns me.


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Originally Posted by mikeflys1 View Post
Just get an escort gt distributor. Same thing as the miata cas but they're 4:1.
Got to thinking a little here... The MSnS-Extra manual talks a bit about certain Mitsu engines that use a distributor with a 4/1 pickup (MSnS Extra Ignition Hardware Manual) and they have a note which says:
"To run these without modifying it to the same spec as the 4G63 then it is best to use MSnS mode using the outer (4 vaned) sensor and keep the distributor."
I honestly can't figure out if that means you can't do wasted-spark in this configuration for some reason, or what the deal is. The 4G63 that they mention is the same 4/2 sensor we have on the NA.
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Old 01-08-2009, 04:54 PM   #9
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Quote:
Originally Posted by Joe Perez View Post
Got to thinking a little here... The MSnS-Extra manual talks a bit about certain Mitsu engines that use a distributor with a 4/1 pickup (MSnS Extra Ignition Hardware Manual) and they have a note which says:
"To run these without modifying it to the same spec as the 4G63 then it is best to use MSnS mode using the outer (4 vaned) sensor and keep the distributor."
I honestly can't figure out if that means you can't do wasted-spark in this configuration for some reason, or what the deal is. The 4G63 that they mention is the same 4/2 sensor we have on the NA.
Hmm that is odd....I can vouch it will do waste spark though. That was my initial setup before modding the crank wheel. You just use the usual wheel decoder and set it up for dual dizzy mode like this..



Set up like this Trigger A & C are for Spark Output A and Trigger B & D go to Spark Output B.
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Old 01-08-2009, 11:01 PM   #10
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You guys are great. I totally misread your first Post Joe, it was late at night....
Appreciate the tip on the escort GT, but I do want to make these ECU units available in bulk for the series, so need to make a cheap fix for the 1.6 owners to use their current CAS. The Omnitek ECU doesn't like the Relucter voltage, nor the drift as RPM increases.
I could just let them run Batch fire as already set up, but I am hoping to get them just "a little more".
The idea is to use as much stock 1.6 stuff as possible to keep costs down.
I didn't get a vote on the Turbo selected... I'd go with a smaller faster spooling twin input turbo to get to the fuel limit faster...

Spec Miata Community: SMTurbo Mazdaspeed kit
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Old 01-08-2009, 11:30 PM   #11
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Quote:
Originally Posted by drgoodwrench View Post
I do want to make these ECU units available in bulk for the series, so need to make a cheap fix for the 1.6 owners to use their current CAS.
You can easily do it so that it'll work with the stock 4/2 CAS output.

With regard to the second (CMP) input, you can clearly see that while the rising edges of CMP always occur just before a rising edge of CKP, the falling edges are different- one occurs before a CKP falling edge, and the other occurs after a CKP falling edge.

If you consider CKP to be a state machine (rather than just a bunch of edges) then you can use it to validate CMP. Trigger your cycle counter reset with CMP falling edges, and ignore CMP falling edges which occur while CKP is low (or while CKP is high, either way.) That will give you an effective 4/1 signal from the stock 4/2 CAS.


Which ECU are you using?
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