rmiata

Hey everyone,
I have put a 2nd gen engine in my 99 miata using the 2nd gen crank angle, and using the 3rd gen computer and harness. Right now it seems like it is sparking on every third tooth.
I was wondering if anyone knows if the pcm in the 3rd gen. needs the resistance of .96-1.26 k-ohm or if it is just for the crank angle sensors or does it even matter? if any body has an idea as to what I can do it would really help?
Thanks
Nick

Cosmo Donk

Well, it seems like you know what you are doing but may I ask why you are using a 3rd gen ECU?? I know the CAS were different in the 2 generations so that might be your problem. I thought the 3rd gens used a magnetic pickup for the CAS rather than a mechanical.

Project84

If you use a 1st Gen distributor, then you won't need the ecu for ignition. I don't know if that will screw other things up, but I called Atkins Rotary about there superchargers and I asked them if I needed the ECU since the SC uses a carb instead of fuel injectors. They say that the only thing the ecu would be needed for is the CAS, unless I went with a first gen distributor, then I could ditch the ecu all together.

rmiata

The reason I would like to have the ecu is I have picked up an AEM computer and I want to be able to play with the fuel and ignition curve to get the most power out of the engine. I have another problem right now and it is that the igniter seems to be warming up, and I am not sure why. My brother has a 94 rx-7 and his doesn't seem to warm up at all.
Any reasons why this might be happening?
Thanks for your info
Nick

Cosmo Donk

Well, I really don't think the 3rd gen ECU will work with that CAS. The igniters might be warming up because they are getting the wrong values from the ECU, although the 3rd gen uses less charge time than the second gen so I wouldn't think that would heat them up.

I really think you need to either do what Project84 said or ditch the 3rd gen ECU. I suppose you could start swaping front covers to change out the timing sensors but that seems like a lot of work and I don't even know if it will work.

rmiata

I have tried the sensors off of the 3rd gen. and it did the same thing as the 2nd gen cas.

Cosmo Donk

Sorry, I'm out of ideas.

How does the AEM work? Is it a piggy-back computer or can it be used as a stand alone? I am assuming it is piggy-back or else you wold just hook it up stand alone

rmiata

the aem goes right into the original place of the pcm. with the same connectors (stand alone system)I can play with just about everything. I think that it might be going into my brothers 94 rx-7, and I am going I think a slightly different way.
Thanks for you ideas