1972 E9 3.0 CSI - Chamonix

[HB Chris]

Iridium plugs are not recommended for m30 motors.

 

[tochi]

Having problems with sparks. Used Denso iridium for a few years now. Replaced them with new ones this season but spark is bad and the engine stalls - especially when sitting for a while.

View attachment 169602

Conventional wisdom agrees with HB Chris✓. Most recommend using standard copper core spark plugs as these were originally equipment from the factory.

That said, if you experienced no problems with Denso Iridium plugs, it is unlikely that switching to a different spark plug brand with a comparable heat range and design would make a noticeable difference in engine operation. Without additional information, perhaps your replacement spark plugs have an extremely wide gap that tests the limits of your presumably "stock" ignition system?