Leading And Trailing Plug Firing At Same Time
 

I have a 1985 GSL-SE with a S4 TII Engine, ECU, and Trans. I has not been running right since the install and when I checked the timing today, the leading and trailing coils where firing at same time, both on the leading mark. This is a big no-no right? It is probably the result of me mis-wiring something, but is their something else that could be causing this? I have been working on her for almost a year and I miss her "ZoomZoom". I guess keep driving my Miata till I get her done. Any input would be appreciated.

You sure you didn't accidentally test 2 leading or 2 trailing at the same time?

I tested the two wires leading to rotor 1.

Did both those wires come from different coils?

Yes, I justed went and checked it again. They come from different coils and definently go to the rotor 1 plugs.

thats bizzare - must have wired something up wrong ( dont ask me what )

I would think that trailing igniting at the same time as leading would be a HUGE problem.

What if the flame ignited backwards by accident? I woudl think you'd need a rebuild shortly after.

I vaguely remember that on a cold day start, the trail and lead fire at the same time. I wrote a thread about it sometime ago.

EDIT: Page F2-75 of the freeee, online, S5 FSM. Series four similar.

I read the FSM page, but it appears that they should only be the same when cranking, not when running.

Yep. What more can I say. OOops.

Although my credibility is going downhill fast, here's a jpg I posted last spring with an engine that had just been started for maybe a half minute. The lead and trail are close together. https://www.rx7club.com/forum/attach...hmentid=173511

You were probably doing the timing with a hot engine so this info probably isn't relative.