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Old 03-01-2012, 09:54 AM   #1
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Exclamation Converting 99-00 CAS to 94-97

I have a 99 engine and would like to have a cleaner setup for the front of my engine as well as having both cams gears adjustable. I was wondering if anyone had swapped out their 99-00 CAS from the front to the 94-97 CAS at the rear of the VC. I know I can get the toda cam gear for the 99-00 but I'd like to just cut the valvle cover and have the gears open for ease of adjustability while tuning and what not. The olny down sides I can see to this swap are the cost of the 94-97 CAS(new they can get up to $300-400 but can be had for 150-200 used) Anyone that's done this are there any other issues/downsides/benefits?

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Old 03-01-2012, 10:03 AM   #2
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What ECU? cause I'd prefer the cmp/ckp sensors of the 99 motor over the CAS personally.
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Old 03-01-2012, 10:25 AM   #3
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AEM, why would one sensor/setup be better than the other? the 94-97 is connected to the camshaft and th 99-00 just reads like a trigger wheel.
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Old 03-01-2012, 10:39 AM   #4
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well the 94-95 is just the CAS running off the camshaft for both the crank and cam signals, so there's jitter involded.

the 96-97 has a crank sensor and uses the CAS for the cam sensor IIRC. which is still perfered.

the 99-00 uses a crank and cam sensor. which is effectrive the same as the 96-97, but the cam sensor is reading off the intake cam instead of being driven off the exhaust cam.
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Old 03-01-2012, 01:10 PM   #5
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Either way I'll still be running the 12 tooth crank wheel with the crank sensor.
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Old 03-01-2012, 01:23 PM   #6
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ah
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Old 03-02-2012, 10:58 AM   #7
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bump? anyone? Will I be the first?!?!
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Old 03-02-2012, 11:09 AM   #8
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no, but there's not much to really discuss here.
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Old 03-02-2012, 11:12 AM   #9
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Quote:
Originally Posted by Braineack View Post
well the 94-95 is just the CAS running off the camshaft for both the crank and cam signals, so there's jitter involded.

the 96-97 has a crank sensor and uses the CAS for the cam sensor IIRC. which is still perfered.

the 99-00 uses a crank and cam sensor. which is effectrive the same as the 96-97, but the cam sensor is reading off the intake cam instead of being driven off the exhaust cam.
Not really that relevant but, I'm like 99% sure the 96-97's used the CAS exactly like the OBD1 cars did and the crank mounted wheel was just for misfire detection.
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Old 03-02-2012, 03:29 PM   #10
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no, but there's not much to really discuss here.
Actually there is because from what i can see there's not much info on it and none of my original questions have been answered. Why did mazda choose to switch the rear mounted exhaust cam sensor for a front mount ticker style sensor? only benefits I can see are cheaper sensors and easier to work on but car company's aren't usually out to make their cars have cheaper parts and easier to work on.
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Old 03-02-2012, 03:54 PM   #11
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Quote:
Originally Posted by mikeflys1 View Post
Not really that relevant but, I'm like 99% sure the 96-97's used the CAS exactly like the OBD1 cars did and the crank mounted wheel was just for misfire detection.
Correct.



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Why did mazda choose to switch the rear mounted exhaust cam sensor for a front mount ticker style sensor?
I don't know what a "ticker-style" sensor is, but ignoring the '96'-97 crank sensor (which, as has been noted, was used only for OBD-II misfire detection) there are essentially three different sensor setups:

1: The '90-'97 cars used the cam-driven "CAS." This was a natural evolution for the previously distributor-based B series engine, and was "good enough".

2: In '99, they upgraded to a seperate crank sensor and cam sensor. The crank sensor provided a more stable trigger signal, as it was not affected by timing-belt slop. The cam sensor was placed at the front of the valve cover, and detected bumps on the intake cam pulley. I don't know why this specific location was chosen.

3: In '01, the cam sensor was moved to the top of the valve cover, and read marks cast into the camshaft itself. This was necessary in order to accommodate the VVT system, as the ECU needed to know the exact position of the cam, which was not the same as the position of the cam pulley.




Ok, long story short: If you can program the AEM to understand the rather unusual pattern which would result, there is no technical reason why you could not run an NA-style CAS with an NB-style crank sensor.
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