Monsoon 350 SS Fault Code SPN: 65591 FM:7 Misfire Cylinder 1

[DMx]

I’m having issues on my 2013 Malibu 23LSV with a Monsoon 350 SS with Cat exhaust (fuel injected).  I had it in the shop (Malibu dealer) for a full tune up (new plugs, wires, rotor, cap, fluids, filters, etc) after it first threw the code. On the next trip out, it was fine for half a day and then threw the same code again. After doing some digging on here, and speaking with an Indmar rep, I went ahead and replaced the brand new plugs the dealer put in (AC Delco MR43LTS) because the Indmar rep confirmed that mine should have the 41-101 plugs since it has the Catalytic exhaust. I also replaced all the fuel injectors with brand new ones. On first start up, it actually started faster than before (didn’t crank as long as normal); I’m thinking because of the new, proper plugs. However, after 3 heat cycles (per Indmar rep: engine has to get above 160* and then cool down below 140* to complete one cycle), I still was still throwing the code. I am able to board/surf behind it, and just have to silence the annoying alarm every couple of minutes which gets pretty annoying. From what I’ve read, the next step may be O2 sensors and then possibly the cats themselves. I don’t want to keep throwing money at this thing blindly, so please let me know what y’all have encountered and what worked for you. Thank you in advance.

[csleaver]

What is the actual reoccurring fault code (SPN FMI)?

[DMx]

SPN:65591 FM:7

[Laceytorg11]

We have had the same problem the last two summers. We have tried everything as well. Our boat runs great but the alarm goes off every 7 minutes and it is so annoying. There are some other posts on here that the dealership might need to reprogram or flash something. I am determined to get to the bottom of it soon. I will keep you updated. Let me know if you figure it out too. We have a 2013 21’ LSV 

[csleaver]

There are many things that can cause misfires, like poor cylinder compression, worn spark plugs or ignition components, low or high fuel pressure, clogged or leaking fuel injectors, improper cam angle adjustment, or even excessive drivetrain/ running gear vibration. 

I recommend starting with a compression test, inspecting the ignition components, and check the fuel pressure. 

[Joshua]

I am having same issue with my 2012 VTX. Exact same code. Puin new plugs and wires and misfire was gone for next 3 trips out. 4th trip and code comes back after about 30 sec of WOT. Did you figure anything out?

[oldjeep]

Check with dealer to see if misfire calibration update has been loaded into ecm.  I fought this for years with my 2012 and it turned out that indmar had released a fix for it years ago. Cost me about $50 to make it go away forever.

Edited July 4, 2023 by oldjeep

[Jjm08012]

What dealership did the update for you?

 

[donrussellbrown]

Any updates to this thread?

[EchelonMike]

I had this same code, and a tune up fixed my issue.  However, when researching this issue, @oldjeep is correct in that Indmar has a "performance update" that the dealer can re-flash on the ECM.  Every thread I read on this issue where a tune up did not solve the issue, the reflash fixed it.

[oldjeep]

On 9/27/2023 at 9:17 PM, Jjm08012 said:

What dealership did the update for you?

 

Lol, just saw this.  Fwiw, it was MN Inboard.