6.0 Surging Idle

[Boats Bros]

I was out on the water today and I noticed the idle is surging slightly, it would barely register on the gauge. 2009 ZR 409 with 135 hours. I decided to go for it anyways and the boat ran the entire day while surfing but I always noticed it surging ever so slightly. On the way back in I was going about 25 mph and right before the dock the check engine light came on. Got to the dock and turned the boat off, then turned it back on, and the light turned itself off. Does the ECM store the fault codes or can you read them only when the light is on? It still continued to surge slightly. Going faster than surfing speeds seems to aggravate it like the wife on shark week. Things I have replaced:

In-line fuel filter
Fuel cell filter
Impeller
Coolant

I’ll be checking the wires and replacing the plugs. Does it take the standard iridium AC Delco 41-110? Something still leads me to believe this is fuel related and my gut tells me to check the fuel injectors.

[mlange]

I had a similar problem, although it was at higher RPMs and while it was barely noticeable at first it became worse over the course of a year. Diacom should show any DTCs. In my case it was showing misfires on one cylinder and swapping plugs fixed my issue. Plugs are the 41-110's as you said.

[Boats Bros]

Thank you, I ordered some new plugs and I’ll test the wires when I install the plugs, then lake test it this coming weekend. Stay tuned!