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Mercruiser Warning Engine Misfire Catalyst Damage

TonyG13TonyG13 Member Posts: 1,300 ✭✭✭✭
edited October 2022 in Engine Discussions
On the way to get gas this morning this Warning popped up: "Engine misfire. Starboard Engine. Reduce engine speed to prevent catalyst damage. Service Engine Soon." Engine sounds fine. Any ideas what causes this and any potential solutions? Hopefully something simple?

The boat is going in on the 17th, so If I can't figure it out by then, I can have my yard take a look.

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    mvnmvn Member, Moderator Posts: 744 mod
    Search for "engine misfire causes" and you'll see the most common reasons such as faulty ignition (coils, distributor cap, ignition wires, spark plugs) or faulty fuel system (plugged injectors, restricted fuel filter or low fuel pressure). There are more reasons but these are the common ones. 

    Mark 
    Good,  fast,  cheap.... pick two. 
    2019 MTX20 Extreme

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    oscar1oscar1 Member Posts: 748 ✭✭✭
    Did you find out what was the issue for the alarm. The same alarm just happen to me today.  
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    TonyG13TonyG13 Member Posts: 1,300 ✭✭✭✭
    edited May 2023
    In my case it just needed a tune-up. @mvn's first guess was correct!

    I had spark plugs, rotor, and distributor cap replaced. The yard cleared the code and it did not return. So it was an easy fix.

    The mechanic said if the code would have come back it could be the O2 sensors on the catalytic converter (there are two sensors) - but looks like we got lucky.

    So just start with the easy stuff first and see if that clears the warning.
    Post edited by TonyG13 on
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    oscar1oscar1 Member Posts: 748 ✭✭✭
    I going to do the same tomorrow. Thx
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    rasburyrasbury Member Posts: 8,314 ✭✭✭✭✭
    We all jump (mw included) to the worst possible scenario don't we?
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    TonyG13TonyG13 Member Posts: 1,300 ✭✭✭✭
    oscar1 said:
    I going to do the same tomorrow. Thx
    BTW - This code will not clear itself. So you'll need a mechanic with a Rinda TechMate or similar computer to clear the code for you. And while he has it connected ask him to look through any other past codes in the system. You may find other items to keep an eye on.
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    earl1z19earl1z19 Member Posts: 340 ✭✭✭
    I seem to go through this once a year. The code pops up. I have found a few causes for this. Yes the o2 sensor could be going bad but this can also be caused by the fuel pressure regulator being clogged and pushing the fuel pressure above 43psi. When the pressure exceeds 43psi the o2 sensor tells the ECU to lean out the mix. The ECU cant make enough change to compensate for the increase in fuel pressure and then it throws the code as noted above. I have also just had this code appear for what seams to be no good reason. I will have the code cleared and then while the boat is still on the scanner run it from a cold start all the way to running temp. You can see what the O2 sensors are doing and see if there is actually an issue. I would recommend pulling and cleaning the pressure regulator to see if it is clogged at all and then have the code cleared out. Run the boat and see if it pops up again. You can also test the O2 sensors with a voltage meter if you think there is an issue but the scanner software should also be able to tell you if they are not working properly.
    BTW, the beeping that the vessel view makes is enough to drive you crazy, there should be a way of muting that after you acknowledge the issue but there isn't.
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    rasburyrasbury Member Posts: 8,314 ✭✭✭✭✭
    I'm often glad for an older boar...no 02's or cool fuel...
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    oscar1oscar1 Member Posts: 748 ✭✭✭

    I was able to fix the misfire issue with starboard engine, but then these two alarm show up which I was not able to fix the communication issue. The engine run perfect, but I can not see any inputs in the vessel view from the starboard engine, but i can see port engine when she is the only one running. a soon i turn starboard engine on the vessel view information disappear for both engine. This issue drive me crazy today.
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    Rich_Rich_ Member Posts: 155 ✭✭
    Comm error sounds like a weak electrical connection somewhere. Find any harness plugs, pull apart, look for signs of corrosion, reseat. Hopefully goes away as is, remedy any bad contacts. Thats where I would start
    Rinker sold but still have other boats        Eastern LI, NY
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    oscar1oscar1 Member Posts: 748 ✭✭✭
    I was able to correct the two faults today. The issue most in the 14 pin engine plug, where pin G color blue cable which it is the communication cable to the smart-craft, it was only half way into the plug. So if  you are DTS, connect to a vessel view with axius system in your boat. The pin (G) is the communication cable for the system to work correctly.
     
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