2006 verado 250 intermittent miss

[djwlbk]

I have been chasing a miss that comes and goes for a while now. Today I ran across the harness plug on the number 4 coil seems to either not connect as good or I have a bad place in a wire. Has anybody replaced a plug or had any similar issues? It looks as though the harness is 2 piece. Any recommendations or advice I can get please let me know. I sure hope this is that annoying miss I've been chasing and hope I can repair it. Thanks for any help.

[EuropeanAM]

If you would, please take a moment to review the Forum Announcements (at the top of the Forum) and provide the Required Info with your post. Thanks!

How many hours on the engine, and on the current Spark Plugs?

Can't really comment on the wiring/connector for #4 coil, without seeing or inspecting what you are describing.

[djwlbk]

Thanks for the reply. I have 704 hrs on the motor. I had replaced the plugs last year with the denso equivalent but just put new oem in. Also drained fuel and replaced fuel filters . As to the wiring/connector for the # 4 coil , Mercury sent me the part number as 879346A46 and it is my understanding I will have to splice it into the harness when replacing. For now I have shimmed the plug a little and it seems to do ok now. I plan to take it out this weekend and see if any or all of the above have improved my situation. Also Don if you could send me an email address I would like to shoot you a picture of the plugs I took.

[EuropeanAM]

PM sent

[hoytrb]

Have you checked for a pencil coil breaking down under load? That is a very common issue with these motors and a rather easy fix. If you do a search on the verado club website there is more than you want to read about it with how to check the coils as well. I have had 3 go bad on my 250 verado in the last 4 months.

[djwlbk]

Thanks for the replies. I ended up finding one of my plugs on one of my coils nor getting a good connection. I think it's good now last couple times out it ran like a top.