Not only was my RX8 coil discolored on the bottom.

IT WAS DEAD!!!!!!!!!!!!!!!!!!!!!!!!!

I could have lost the engine any minute.
No indication what so ever that it was dead.
No noticeable loss of power. Of course that
was the trailing (top) plug.

If the check engine light had come on I would have known
about it but it did not!!!!!

Minutes away from a new engine!!!!!!!!!!!!!!!!!

Check those coils folks. I'll do it for you including
shipping for $20 cash. All four. For a limited time
only. Better yet get four new ones.
Mine should be in in a day or so.

Paul Lamar

Paul...a Mazda service bulletin says that the discoloration on
the bottom of the coils is normal and is not an indication of
anything going bad.  One of the Mazda forums agrees with some of
the messages saying that they have as much as 130,000 miles on
discolored coils and testing showing no problems.  However, as
you said, testing should be done after about 25,000 miles. Mazda
suggests just a resistance test...attached is a copy of their
service bulletin.

Harley

Thanks Harley for adding to the info on this.
So far I have no less than 8 RX8 coils. I know my tester is working
as some spark and some don't and I was very very careful about getting
the drive to the coil right. The good old 50 cent CD 4050 does a masterful
job of driving any transistor or FET. I have one RX8 coil that is bad with
no discoloration.

I will have a total of 12 shortly with the new ones coming from
Pep Boys. Those too will be tested.

In addition I can open and close the spark gap to measure the
output voltage.

I also have two running RX8 engines I can test them on.

I have also noticed one other thing about them. They draw
a huge amount of current during the 2 ms dwell time so make
sure the ground and 12 volt wire is short and of high gage (18).

I see from the Mazda service bulletin the trailing coil
does not work during cranking. I wonder if Tracy implemented
this feature? I also wonder why Mazda did that?

Here is a simplified schematic of Tracy's EC2 to make it
a bit easier to understand.

I'll do one shortly for the RX8 coils.

Paul Lamar

I discovered the fact that the RX8 coils took such a surge
current it was seriously affecting the 10 Amp 12 Volt power
supply in my RX8 coil tester set up.
The back EMF could kill the capacitors in the power supply
so I replaced it with a motor cycle battery.

I also re-drew Tracy EC2 schematic to make it more clear.
Apparently the PCM module has a 15 pin D sub min connector
so I will order a 15 pin break out board from Winford
Engineering. http://www.winfordeng.com/products/brk37.php
tomorrow. I did not draw or wire in the coil and injector disable
switches as I don't need them for the test stand.

One of the little tricks I discovered is buy  old cheap parallel
printer cables. They have 18 wires in them, all of a different
color, shielded with a ground wire in a sturdy vinyl jacket.
They come up to 12 foot lengths. Cut off the connectors and
throw them away.

Ideal for the cable from the PCM to the EC2.

The wires are not large enough to use for
injectors but that can be bought from DigiKey in a vinyl
jacket.

Hopefully I can make a large improvement in the neatness of
the ACRE test stand wiring. Also with the help of the break out
boards one should be able to wire this up in an hour.

Paul Lamar