We just complete our 16k maintenance back in August. We have had 4 random cold cylinders since the overhaul. These cold cylinders happened at 222, 235, 566, 730 running hours on the set of plugs. All CCO events were able to be reset very quickly and each CCO has been a different cylinder. We run the engine continuously and only had CCO near the 2000 hour interval in the past. This is the first time we have used the bridge spark plugs, we are planning on trying the older style at the 18k to see if the CCOs stop after swapping the plug types. Has anyone seen an increase in CCOs with the bridge type on a base loaded engine?
I will second what Joel said. We have had good performance from the Wartsila bridged plugs, with extended life and they are able withstand a higher start count. That being said, they are roughly 3x the cost of the standard Denso plugs (previous Wartsila OEM plug).