Auxilliary Coils

[leftofcentre]

Lower left & right plugs/coils -

When do they fire? All the time? Only at certain load or rev range?

Just for my own interest really.

Anybody got any hard facts? (Instead of opinion?? )

 

[Steptoe]

Lower left & right plugs/coils -

When do they fire? All the time? Only at certain load or rev range?

Just for my own interest really.

Anybody got any hard facts? (Instead of opinion?? )

Pull the main coils and ride around using just the lowers and you''ll find out yourself instead of going by someone elses opinion.

 

[leftofcentre]

Pull the main coils and ride around using just the lowers and you''ll find out yourself instead of going by someone elses opinion.

Was gonna do that but "apparently" it fucks up the coils and ECU

 

[tonkatoy]

You could always stick a pair of spare plugs in the caps you've removed. I doubt very much if the ECU or coils can tell the difference between plugs that are in and those that are not. The chances are that if it starts and runs for more than a few seconds that the secondary plugs are used all the time. However this is just surmise/opinion.

Dave

Was gonna do that but "apparently" it fucks up the coils and ECU

 

[Pukmeister]

Was gonna do that but "apparently" it fucks up the coils and ECU

Cobblers, I've had lower coils melt down into mush without harming the ecu.

 

[vikingiii]

Lower left & right plugs/coils -

When do they fire? All the time? Only at certain load or rev range?

Just for my own interest really.

Anybody got any hard facts? (Instead of opinion?? )

Below is an explanation provided by BMW in 2004 (BMW R1200GS Press Release). I think it explains rather well.

Featured in all BMW Boxers since 2003 (with the exception of the 850cc power units), dual ignition has been further modified and improved on the R1200GS. The auxiliary spark plug is now arranged at the outer edge of the cylinder, the ignition timing of both plugs being freely programmable as a function of load and engine speed in order to further optimise running smoothness, emission management, and fuel economy. Referred to as "phase shift", this adjustment process is maintained consistently all the way from part load to full load.

In practice, this means different ignition timing points on both spark plugs in defined control map areas. When approaching full load, where dual ignition no longer provides any benefits, the phase shift effect is so large that the spark crosses over on the auxiliary plug in the expansion cycle (60 degrees at TDC). For all practical purposes this corresponds to single ignition on the central spark plug under full load.