I think there's a lot of misinformation about this on the web. These are my thoughts...
On a CF2 TS engine coil 1 fires both primary spark plugs on cylinders 1 and 4.
Coil 4 fires both secondary spark plugs on cylinders 4 and 1.
Firing order is 1-3-4-2
So, cylinder 1 primary spark plug is fired by coil 1 at 0º crank rotation at beginning of power stroke. Coil 4 is firing secondary plug on cylinder 4 at the end of exhaust stroke.
cylinder 3 primary plug is fired 180º after cylinder 1 primary plug
cylinder 4 primary plug is fired 360º after cylinder 1 by coil 1, the exact same moment at the end of exhaust stroke on cylinder 1, when coil 4 fires secondary plug on cylinder 1.
So, switching leads of coils 1 and 4 with have no practical effect. Both coil will still fire 2 spark plugs 360º fased out on crank rotation. This is the same switching the leads of coils 2 and 3.
The only advantage I can think on this configuration is that a cylinder is serviced by 2 coils, and on a coil failure, cylinder still runs. Runs much better if only the coil firing the secondary plug fails. Harder if primary fails.
Disavantage, it's harder to diagnose a failing coil pack, specially the ones only running secondary plugs.
Edited text in bold.
Last edited by alfizta; 12-08-14 at 09:47.