I heard or read somewhere once that the main purpose of the trailing plugs were to help clean up emissions. Have any of you ever heard this or know if this is true. If it is true wouldn't it be easier to just remove those plugs and seal the holes if you were not running any emissions anyway.

 

They are there also because of the design of the combustion chamber on the rotary. They actually do aid somewhat in combustion.

 

is it true that the trailing sparks twice during its cycle and why?

 

i belive it's the leading that fires twice, and its to help finish igniting unburnt fuel


-Shawn (don't quote me on that)

 

*edit* I am a dummy, no need to read what I posted.

 

Okay, shoot me...

Here is what is said on:
http://www.rotaryengineillustrated.c...nition101.html

As the working chamber approaches Top Dead Center (TDC), the leading plug fires first, starting the ignition of the air-fuel mixture and contributing most to the generation of power. The trailing plug typically fires 10 to 15 degrees later and effectively completes the combustion of the remaining air-fuel mixture above the minor axis of the trochoid housing. Additionally, the leading plug fires a second time late in the power stroke, which is called a "wastespark". The wastespark is done to simplify the ignition system by allowing both leading plugs to be fired "on the same channel" (one coil, one signal) . Basically, both leading plugs always fire at the same time, so there is an extra (wasted) spark during the power stroke. The trailing plugs cannot be fired in wastespark mode due to the location of the plug above the minor axis -- when one trailing plug is firing, the other trailing plug is already in the next working chamber, where it would preignite the incoming air-fuel mixture.

 

Check this out:

https://www.rx7club.com/forum/showth...hlight=running

 

THANK YOU

-Shawn (<--- just being your average american jackass)

 

Yeah yeah....I blew that one.

Funny thing is, the correct answer was 30 seconds away via Yahoo. Search string was "Trailing Spark".

Original eh?

Watch this...(deletes previously misinformed posts)

jarrett

 

Just one item I'd like to add. To see performance difference, disconnect the trailing igniter and drive the car. You'll notice the difference. On a TII (stock), esp. S4's there is a difference, but it's hard to tell because of the turbo coming on. Better make sure trailing plugs are firing properly before doing the test, or no difference will be noted.

 

the leading ignition is one coil setup. very simple. two plugs fire at same time.

the trailing ignition is 1 two coil steup. much more elaborate than leading. The ECU sends out 2 pulses: regular ignition signal and select signal. The latter one determines which coil (and plug) will fire.

if you have time to waste,
see my web page under 'ignition'

hugues -

 

Hey Hugues, is that a Renault Alpine in your Avatar? Nice.

 

Good eye, Mr. Eccentric, the A110 "berlinette"

hugues -