2003 GTX 4Tec Ltd--Missing problem

[Chris and Sue]

We have a 2003 GTX 4Tec Ltd. After it sits for days or weeks, especially the first time it's in the water for the season, when it first starts up, it misses on one cylinder at various throttle settings. The missing goes away after it runs for 10-15 minutes, but later it misses at idle. The initial missing is worse the more weeks it's out of the water.

Looked for codes, there are none. Any ideas?

 

[Dennis]

Replace the spark plugs. (3) NGK DCPR8E

 

[Chris and Sue]

Thanks, Dennis, we'll try that.

 

[aklim]

In a car, I would put a known good plug and ground the threads before cranking to see what color the spark is. I am quite certain that the color I want to see is blue. I would GUESS that is what we would want to see but not 100% sure.

Also is there a way to see which cylinder it is? I would say that if you disconnect one cylinder and it doesn't change the idle as much as disconnecting the others, we can see that is the "bad" cylinder.

 

[Chris and Sue]

The spark plugs did the trick!! Thanks again.