2004 SV211 ZR6 - Engine starting to miss - down on power

[dfoster]

I have about 480 hours on my 04 SV with a ZR6 engine. It has run like a top for me the past 5 years. Done oil changes and FCC and impeller each year. Put on 60 - 80 hours a year.

New Alternator first year, belts last year. But overall, nothing needed, etc.

Part way through this summer it seems to have started to "miss" a bit. A little rough when idling and seems a bit down on power when pulling a hole shot for slalom. But it continues to run and pull fine. No errors shown on the dash. It does get a bit better once warm, but is still noticeable.

Was thinking of putting in new plugs, or pulling them to see if any are looking dark or showing signs of a miss. Does anybody have specs for the resistance that the coil should show or some way for me to check that those are fine?

Do people only use the PCM sparkplugs? ($100 for a set vs $60 or so?) Same with the coils? These shouldn't be anything special, but don't want to cheap out on something that will probably last me several more years.

Anything else I should check? Boat is on the lift now thru Oct, so figure I should take a look before I run it the rest of the fall.

[d_nodixon]

I would start with plugs and wires first...that should do the trick

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[aaronmt]

Definitely start with the plugs,they have a slightly different part number then the originals.We just bought a ZR6 220,previous owner told me they change the plugs ever 3 years.However when im a bit neurotic about performance and thought it just wasnt perfect.I pulled the plugs out and found them to have factory overspray on them so they were never changed.These boats tend to idle alot for the stereo and go slow for surfing.The plugs on mine had a ton of idle time and carbon build up.Even iridium plugs need to be run hard once in a while to clean up.

[sfjakey]

Plugs. Run 91 octane and they last longer

[charlesml3]

Everyone is saying "spark plugs" but at 480 hours I'm betting it's a worn distributor cap & rotor. The trick to fixing this is work your way through the problem, replacing one thing at a time. Yes, replace the plugs. They're cheap. If that doesn't fix it, go to the cap & rotor. If that doesn't fix it, replace the plug wires.

Or you could do what I did and say "The **** with it" and replace ALL of that at once. The lake I'm on doesn't have a great inventory of parts on-hand so they had to order them. I didn't want to keep coming back for the next item on the list so I just replaced it all...

-Charles

[IMScarlet]

Plugs Usally start failing after 300 hrs so you will most likely find that's the issue ZR6 doesn't have distributer so can't be anything to do with it and I have had wires last over 2000 hrs on that engine BTW PCM recommend plug change at 300 hrs in their service schedule. Can't remember AC-DELCO plug number as used by PCM but NGK equivalent is a PZTR5A

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[dfoster]

Got it. Ordering plugs. They are overdue, and then will start from there if that doesn't do it.