Miata 1.6 . Bad CAS?

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shifter
MS/Extra Newbie
Posts: 4
Joined: Mon Nov 17, 2014 11:29 am

Miata 1.6 . Bad CAS?

Post by shifter »

I've put together a MS1 3.0 with the instructions on DIY Autotune to use the factory igniter and coils. The car will start, but run very rough for 10 seconds or so then smooth out. When I check for spark while cranking only one of the coil packs is firing. I've switched the input pins on the igniter and the working coil pack will change. I've done a resistance check on both coils and igniters so this leads me to believe both are functioning properly.

I've checked the resistance on all the ignition related pins to the MS plug and they are all good. I purchased a ms1 3.57 and configured it just as the 3.0 was and I am still getting the same result.

Yesterday I pulled the CAS apart and spun it around by hand while checking voltage. The crank section (2 slots) is showing 5 volts on my DVOM, while he cam section (4 slots) is fluttering some very small voltages. If I spin it around by hand I am only getting 1 functioning coil for 10 seconds or so, then the 2nd coil starts working. This makes me think the CAS is out, but when I am spinning it around by hand I can hear the injectors clicking each time 1 of the 4 slots passes even though the spark does not happen.

Does this sound like a failing CAS, or could it be something else?

I do not have a datalog with me, but I will post one this evening.
shifter
MS/Extra Newbie
Posts: 4
Joined: Mon Nov 17, 2014 11:29 am

Re: Miata 1.6 . Bad CAS?

Post by shifter »

so I broke a rule of efi tuning and threw a part at it without proper diagnosis. I replaced the CAS and coil pack with spares and there is no change.

I've attached a log of the CAS being spun by and hand I see a lot of resets.

I took my DVOM and measured resistance of every pin in the 37 pin harness and all of the grounds are < .001 ohm and everything else checks out.
dave
Helpful MS/Extra'er
Posts: 88
Joined: Mon Aug 11, 2008 7:53 pm
Location: Cleveland, OH

Re: Miata 1.6 . Bad CAS?

Post by dave »

so after the 10 secs, all of the coils function normally for the rest of the drive?
shifter
MS/Extra Newbie
Posts: 4
Joined: Mon Nov 17, 2014 11:29 am

Re: Miata 1.6 . Bad CAS?

Post by shifter »

well sometimes its 10 seconds, sometimes longer. And you have to work the throttle to keep it running until it smooths out, but then it starts hitting all 4. I have not driven the car, this is a swap in to an older 60s vehicle and still has a couple of other things to address before it hits the road.
shifter
MS/Extra Newbie
Posts: 4
Joined: Mon Nov 17, 2014 11:29 am

Re: Miata 1.6 . Bad CAS?

Post by shifter »

So this Miata engine still had the factory throttle position switch. I swapped it out for a variable TPS off a Kia and the problem seems to have gone away. Its running and driving well enough to start tuning.
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