Bad coils or am I missing something?

[UnorthodoxCreations]

I've had my 2005 AR230 for 5 summers and have had my share of issues

Year 1, ECU went bad, sent off for repairs.
Year 2, other ECU went bad, bought a new one
Year 3, previously repaired ECU went bad, sent off for repairs along with the one I never repaired from year 2.
Year 4 was awesome. We had no issues and got to use the boat more than ever and go new places. I also now have an extra ECU just in case.

We are now on year 5. We used the boat for a day in June and had no issues. We took it to my in-laws for a long weekend and I noticed the STB engine being down 1000 rpms or so compared to the PORT at times. It wasn't all the time but occasionally. We left the boat at my in-laws and I decided I would bring fresh plugs for both engines since it was probably at least 2 years since they were changed. We don't put a lot of hours on the boat in a season but I didn't know what else to do. The tips of the old plugs looked fine but I changed them anyway. Honestly the boat seemed to run worse after changing plugs. It was down RPMS more often. I tried to diagnose with YDS software but my laptop died before I could do that and I didn't have a charger. I decided to put in the my spare ECU. I also pulled the plugs on that engine to double check my work and look for any other symptoms. After doing that the boat ran perfectly.

We have a big family vacation next week so I decided I want to double check everything at home where I have more tools, availability to get parts and resources in general versus being at my in-laws in the middle of nowhere. I also wanted to change the oil in case it was contaminated with fuel. I trailered the boat 5 hours home and Monday night my dad and I started checking it out. I started by swapping in the ECU I had pulled out. I then tested all injectors. All the injectors worked fine. None were sticking open like what happens with an ECU failure. This was somewhat of a relief but also puzzling. Something was definitely wrong but ECU/injectors were testing fine and their was no gassy smell or signs of gas in the oil. I didn't change the oil yet but the oil level is normal.

I then decided to check the coils. All the coils fire off good with spark but I was noticing some were sparking out the side of the coil body if they didn't have a plug in them. That shouldn't be the case right? I could get 3 of the 4 coils to spark through the side of the body and it was a bright spark. I'm thinking this is my issue. When running, especially under load some of the coils are sparking out the side causing RPMs to drop. I have a car with a vented hood that allows water to get in the spark plug holes when it rains. It ruins the plug boots and causes them to arc out and lose power, especially under load and this seems like a similar situation. I have new coils coming tomorrow that I'll put in. I also put together that both times I messed with the coils, it changed the running condition. When I changed the plugs at the beginning of the weekend it actually ran worse and when I changed the ECU/checked plugs it ran better.

Does it seem like I'm on the right track or am I missing something or is there something else I should be checking? I'm really hoping it's not an early ECU failure that isn't showing up with the computer because I caught it early but all signs point to the ECU being fine.

 

[UnorthodoxCreations]

I put the new coils in the starboard engine and it worked great all week. When I first put the boat in the water the port engine didn't want to start. After multiple attempts it finally started and stayed running but it didn't want to rev up. It would stop around 6,000 rpms. After multiple restarts it finally would run normal. I decided to put new coils on the port engine but it didn't make a difference. That continued for most of the week. After the boat would sit for a bit it would take multiple restarts to run past about 6000 rpms. Once it was running right it ran great and the boat would do it's normal speed of almost 45mph(GPS). Rarely while running the port engine cut back to 6000rpms and I would have to restart the engine. That was maybe 2 runs out of 30+.

We got back from vacation today so that boat hasn't run for over 24 hours, probably the longest it sat all week. I wanted to plug in with the computer and see if I could diagnose anything. The port engine was very hard to start. I had to keep cranking many times for it to finally start. Once it was running it seemed fine and I couldn't find anything with YDS. I'm stumped on what is going on. Maybe a fuel pump on the way out but to me it seems more electrical in nature.

 

[UnorthodoxCreations]

While running on the hose, once the port engine was running I couldn't get it to not rev. It would do 10,000+ easy but it's under no load. Maybe a fuel injector on the way out? I can pull them and visually inspect.

 

[Babin Farms]

What do the spark plugs look like? They may be able to tell you what’s wrong. Next, I’d try to swap coils with the other engine to see if it follows the coils or stays with the engine. Use a sharpie to mark them 1-4 so you know where they go in case one is bad. If it stays with the engine I’d try a new set of plugs. After that I’d pull the plugs when it’s acting up to see if any of them are wet with fuel and not firing correctly or if they all look like they’re supposed to.

 

[UnorthodoxCreations]

What do the spark plugs look like? They may be able to tell you what’s wrong. Next, I’d try to swap coils with the other engine to see if it follows the coils or stays with the engine. Use a sharpie to mark them 1-4 so you know where they go in case one is bad. If it stays with the engine I’d try a new set of plugs. After that I’d pull the plugs when it’s acting up to see if any of them are wet with fuel and not firing correctly or if they all look like they’re supposed to.

I didn't pull plugs last night but that would be a good idea to do, especially if it's struggling to start. I can see if they are getting wet or not. Both engines have new plugs and coils. I can try swapping coils around to see if it changes anything.