Correct me if I'm wrong but the pass. side coil is the primary and is for the "power" spark plugs and the one on the driver side is for the "secondary" or exhaust burning spark plugs. Is that right? And thanx for your reply too.
I will correct you because that's wrong, but a popular Myth
Dual spark adds extra power, that's the point of having dual spark plugs, more power
So both spark plugs fire at the same time or there would be no point in having dual spark plugs
What confused people that only knew about distributor type spark systems was they didn't know about the first spark system used in gasoline engines and still used in all single cylinder engines
Crank spark timing, any single cylinder gas engine has this, i.e. lawn mower, ATV, motorcycle, any 4-stroke single cylinder engine, and ALL 2-strokes, lol
The Spark plug fires at each TDC, power stroke and exhaust stroke, very simple system, used since the late 1800's
Ford calls theirs a Waste Spark system, because the spark on exhaust stroke is wasted, and no its not for emissions, it sparks just because its easier to do crank timed spark when doing distributorless engines
Primary and secondary coil pack labels are a bit misleading, in 1989 when 2.3l first got the distributorless system only the Exhaust side(passenger side) coil pack was used for startup and intake side was disabled
This was done to get a hotter spark when voltage drops while starter motor is on
So exhaust side coil pack got the Primary label at that time
Intake side coil pack was enabled after RPMs were above 400, cranking speed is 200rpm, just FYI
1990 might still use the single coil pack at start up
You can test that by unplugging exhaust side coil pack and then try to start engine
If it doesn't start then computer is disabling intake side coil pack on start up
Doesn't matter really unless exhaust side coil pack should fail, lol
But both coil packs are firing every TDC when engine is running, there is no Primary or Secondary at that time
And in case you were wondering why all engines don't use dual spark plugs
Distributorless spark systems on multi-cylinder engines only came about in the 1980's and just a few years later engines with 4 valves per cylinder were being designed, Double Overhead Cams(DOHC)
These offered even more power than dual spark so were a better use of head space(combustion chamber)
Airplane engines used dual spark plugs for more power but also for safety, they have 2 separate spark systems in case one fails, they use both for take off and landing when power is critical but usually switch off one spark system when cruising