Hard to believe it was spark plugs

[cazman]

My 2007 206 with an Excalibur 343 was losing power pulling a skier. I thought for sure it was blocked exhaust or bad fuel pressure. Both checked out ok. Then I changed the spark plugs and no more problems. The thing is that I have 500 hours and the iridium plugs looked great and the motor started and idled fine. I don't know if the computer knows that something was wrong and limited the power, but I never would have thought that the plugs would have created the situation.

[DealsGapCobra]

I’m surprised too but am glad it was a simple fix.


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[cazman]

I lost some power again, but then fine for the last 10 hours. Does anyone know if the computer will restrict power (not limp mode) if something is not right? Seems like whatever was wrong was straightened out after the plugs were changed and maybe the computer needed to reset?? Either way runs good now.

[Helmsmn]

I lost some power again, but then fine for the last 10 hours. Does anyone know if the computer will restrict power (not limp mode) if something is not right? Seems like whatever was wrong was straightened out after the plugs were changed and maybe the computer needed to reset?? Either way runs good now.

I had the same issue, as well as a miss, with my ZR6. I changed the plugs and it ran better but still had the intermittent miss. Then I changed the wires too. Problem solved. I examined the wires and #1 had a burned ceramic insulator. As you said the old plugs “looked fine” but I guess we can’t tell by looking! Put in a set of wires, it might solve your issue. Good luck!


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[d_nodixon]

Plug wires

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[shag]

Distributor cap may also be the culprit. They can get a hairline not noticeable crack and cause issues like that.

[cazman]

Already changed the cap an rotor. Didn't have a miss, just no power above 3000 RPM. That's why I wondered if the computer restricted power. I will change the plug wires. Do I need PCM wires or will any Vortec wires be ok?

[jstallings]

I had same issue, I changed all the fuel filters with no luck and ended up fixing issue with new rotor cap and plugs, I would have never thought that would cause loss of power. As boat started and idled fine just probably 60% of power under load.