The trailing plugs cant fire simultaneously because of rotor postion.The 2nd gen ECU splits the signals up based on CAS postion so that signals are sent to the front and rear trailing coils at the right time to prevent damage.You have to be running the 2nd gen ECU to have a complete direct fire setup on all 4 plugs.

However.....there is a way to make the cruder 1st gen distributor system a little more effeceint.Once you switch the leading system to a direct fire setup,you are left with empty terminals on the distributor cap.These are usually used for distributing the leading spark.If you move the trailing wires to the leading postions,you will send the spark through a carbon button contact, instead of asking it to jump an open air gap to get to the proper trailing plug wire.A small advantage,but an advantage none the less.I also took the opportunity to chop off the top half of the distributor rotor that wasnt being used anymore.That much less mass for the engine to spin,and less load on my distributor.Heres a pic of the direct fire setup and trailing mod,done to my old 13B 4 port w/Yaw nikki.
Ahh,memories.....this is circa 1998.

 

i meant the 2gen trailing coils setup through direct fire but going through the leading on the 1st gen

as you would with normal coils or the blaster coils so in other words the j109 igniters would run the 2gen trailing coils

or are the 2gen trailing coils not suffecint enough i just have a pair sittin on the bench

 

I get a routine, carefully measured 23/24 mpg in my daily commuter (84 GSL), almost all at 80 mph. I always make a point of getting at least 350 miles from each tank.

Ray

Oh yeh, that's pretty much stock, the way the Mazda engineers meant it to be.

 

You can use "A" 2nd gen trailing coil to fire the trailing plugs,in place of the stock coil or a Blaster type coil.......but you MUST direct the juice from that coil through the distributor cap so its sent to the right plug.Hence,its no longer "direct fire" since the juice has to travel through the cap.Its just the stock setup,using a different coil.Using the leading positions on the cap to fire the trailings is just a distribution trick,its not "direct fire" either.
The only way to utilize both FC trailing coils is with the FC ECU handling the distribution duties.

I dont see any reason why the stock 1G ignitor couldnt fire the FC trailing coil,it is just a standard ignition coil.Where the stock ignitors might falter is when you run dual coils for the leading direct fire setup.Thats why its best to replace the stock ignitor with an MSD6 box running off the green and purple wires.
If you wanna do away with both 1G ignitors,you can get 3 MSD6 boxes and 4 Blaster coils (or both of the stock FC coils).Its pricey and bulky,but youll have the baddest,more powerful ignition system going.Youll often see the triple ignition box type setup on all-out race cars.I believe the Jacobs rotary ignition system works the same way.....

 

thanks dude much apreciated