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I figured I'd get some other opinions seeing as I've been getting my butt kicked by this thing for over a year now. 2007 21 VLX with a monsoon 340 with 615 hours on it. Boat spits the service required message and shortly after that the engine fault, cylinder 8 misfire- mechanical system not responding properly code rolls in and puts the boat into limp mode. Only happens when its working hard under load (ballasts full, surfing with at least 5-6 people on board). The kicker is sometimes it will run perfect for a whole day and then the next day no dice. I have noticed when its about to act up the RPMs starts slowly dropping off not allowing the boat to keep up with whatever speed the cruise control is at before it drops right down into limp mode. The person who owned the boat before me took it to the local Malibu dealer twice for the problem and they couldn't solve it however it was winter so they couldn't lake test it. The plugs, wires, cap, rotor and fuel filter(x2) have been replaced. I put a new injector in it and it ran great for a day and half after which hasn't happened since. I've read that a bent shaft or damaged prop could throw off the knock sensors enough to throw the code but those have since been replaced. Compression in all the cylinders are good and close. I've heard the gen 2 in tank fuel pumps are only rated for 500 hours so upgrading to a gen 3 fuel pump may be next on my list although i'm hesitant because the current fuel pump still pushes 45psi at the fuel rail and it wouldn't make sense as to why it runs good sometimes. Not to mention they aint cheap. I currently have the boat in a million pieces seeing as its not surfing season in Canada for another couple months. I have the current fuel pump sitting on the bench, the screens on the bottom look clean and the inside of the tank also isnt bad. A couple specs here and there but clean for the most part. I am planning on giving it a proper clean out when i get home from work in a week. Another thing i've heard about is the lower intake gaskets on the 5.7 vortecs failing and oil making its way into the intake. There was a small oil puddle on the intake plenum when i pulled it off but i've been told to expect that with these motors? I will prob end up doing these gaskets unless I'm missing something obvious. I know it could be a timing issue i just dont have a diacom to check cam angle and i thought that would have been something the dealer looked at the second time around at least. I'm also not closing the door to it being an electrical/voltage issue . The thing came fitted with 3 batteries, a pile of speakers and a sub. I cant remember what the battery terminals looked like last year but when i cleaned them up a couple weeks ago there was a fair amount of corrosion. Sorry for the long write up! Any input would be greatly appreciated.

So I need some help, actually the service technicians at Tommy’s and I both need help. I have a 2017 Axis A24 with the PCM 409 in it with 575 hours on it. Recently I have been having engine trouble as the motor has been running really rough at idle and in gar under power. It has been running below optimum performance and has a significant loss of power, wont even throttle over 4000RPM under heavy load. It has been throwing a MIL code with a service engine alert constantly and only way to clear the code is to reset the batteries only to have the code reappear. It is all under warranty, so I took it to Tommy’s for the service department to diagnose the service engine alert and they told me today that there is a cylinder misfire on cylinders 5 and 6 with the occasional 4. The misfire is constant but here is the problem, they cannot for the life of them identify what is causing it. They have ruled out everything with the ECM, fuel system and ignition system. They did tell me though that they have recently identified this EXACT situation with about 6 other PMC 409s regardless of year or hours on the other motors. They are so stumped about these boats that all have the same issues and same scenarios that they are calling in a PCM engineer to come and completely break down one of the engines to diagnose what is wrong mechanically. Tommy’s actually asked me if I could check the forums to see if anyone else has seen these issues. Any thoughts?

Took out my 2013 Wakesetter 247 out yesterday I was surfing when the warning alarm went off and the boat went into limp mode will not go over 10 mph. Active fault codes states 65592 Mechanical system not responding. My research told me this was a misfire on cylinder #2 so I checked and swapped plugs, wires, coil, and injectors with no change is results. Is there a way to read serial data on boats I see a OBD-M connector but cant find a scanner that will read the data. Any ideas or assistance would be greatly appreciated. The local Malibu Dealer is booked out 3 weeks and wants to charge $175 just to connect and give me a diagnosis. My boat has the Monsoon 427 LS3 engine with 290 hours. This is a really reliable Chevy engine with equivalent of 15,000 miles that has now had 6 synthetic oil changes I cant imagine any serious engine issues. It does run smooth when it runs and doesn’t sound or feel like it has a misfire.