Engine misfire alarm

[benpetre]

Boat:
2010 sea ray subdeck 260
Engine
Merc 350 mag mpi

problem: for years, as soon as I turn the key to “on”, even before starting the engine, the engine misfire alarm comes on. 3 mechanics have looked into it. It has been reset multiple times. I have replaced the plugs, wires, distributor, O2 sensors and still it happens. I saw another thread on this forum discussing it but can’t seem to find the solution! One post suggested the tolerances were too low in the computer settings and a software change would fix it. Anyone know the solution to this alarm? It is really annoying!

thanks

 

[Chris Lovlecae]

I have a 2011 sundeck 260 that does the same thing. I'm making an appointment with the local mechanic to see if there is anything else I can do. I changed the plugs, cap/rotor, and wire. The cap was severly corroded. This is and old thread but I'll post what he finds.

 

[Bill Curtis]

Wife had a Lincoln that did that. Was the injectors the 1st time. Then a loose plug the 2nd time

 

[Jimmy Buoy]

Please clarify "misfire alarm". What beeps are being sounded and what fault is displayed on the Rinda (if you have one).

 

[Chris Lovlecae]

I don't have Rinda. On the trailer, I'd get one long beep with the key in the 2nd postition just before start. SmartCraft would come up, give one long beep and have the Misfire Detected when the engine isn't running. I believe it's error 71. Yesterday, I got 5 beeps while underway with an O2 sensor error that says "Too much fuel is detected relative to the amount of air." Can't remember the code #. Engine seems to run great otherwise. If it's misfiring, I can't tell though after scouring this forum, I guess it's had to tell with marine engines. I get just north of 5,000 RPM WOT. I can't believe I'd get that with one cylinder not contributing but I truely don't really know. Top speed is about 43 MPH which I think is about normal. A few MPH below the boat test video for a 2013 260 Sundeck. Seeing as mine is 12 years old I think that's pretty good.

Here are some screen shots of the faults from Vessel View.

I had the boat out the other day and the trim sensor failed alarm (five beeps) would go off spradically. I know what's causing that (broken wires). But only had the misfire alert. Yesterday, I changed the fuel filter (looks like it had never been changed). Then when I was out and about, I had the O2 sensor alarm pop as well as the misfire.

I figured the misfire, once set, doesn't stop unless it's reset like the OBD faults on a car. Since I don't have Rinda, I have no way to reset so I've just been living with it.

I supressed the trim alarm via vessel view so now the only one I get is what's in this post.
The marina is ooen on Monday so I'll set an appointment to have a mechanic give it a look see. There are a bunch of threads about misfires that never seem to get solved or end up with resolution. I've read where people are spending thousands on mechanics to never get the problem solved. Hopefully, this won't be my case.

 

[Jimmy Buoy]

Ok, I see you have VVM (Vesselview Mobile). Is there no way to ignore the misfire on VVM (until the mechanic gets to take a look)? I see you have a catalytic engine which has more sensors than I'm familiar with. I hope you get some quick and easy results from your mechanic!

 

[Chris Lovlecae]

I can ignore the faults with VVM but these seem a bit more critical than the trim. There are many threads about misfires with these Mercruisers. They all dead-end with no resolution. Most seem like it's an annoyance and something jacked in the ECM. If they can't find anything, then I'll ask about that. I'd assume after 12 years (at least as far as my situation is concerned) there'd be a library of these faults and what was done to fix them from Mercury. I've emailed Mercury customer service about other things and they've been Johny-on-the-spot with pointed responses and not the typical "did you make sure the battery was plugged in" type answers. We shall see! Boat seems to be running great despite the issues so I'm hoping it's a hiccup and I can go about my way. I'd assume if I had a dead cylinder I wouldn't be able to make that RPM but we'll see!

I read in a different forum for another boat brand that uses Mercs about clogged injectors from paint chips in the cool fuel module. If the injector was the issue, that'd be something that doesn't seem to fit the evidence but who knows.

Fingers crossed!

 

[Chris Lovlecae]

I haven't been able to find a mechanic in my local area yet. I may need to bite the bullet and pay for the Rinda tool. In the meantime, I ran accross this bulletin from Mercury Marine that may shed some light on the issue. Of note, there seems to be an issue with the 50 AMP yellow flag circuit breaker that has been related to the misfires. I'm not sure why that would do it but my engine has one of these yellow flag type CBs at least. I found it sort of tripped when the trim wouldn't work. If the new style button is cheap, I may swap it out just for fun. The bulletin says that the engine at either 2,000 or 4,000 RPM is at its most stressful and the 50 AMP CB can cause it to misfire somehow. Just a thought for those of us with this issue. To be clear, I haven't tried swapping the CB out but may. If I do, I will let you all know.

 

[Bill Curtis]

I haven't been able to find a mechanic in my local area yet. I may need to bite the bullet and pay for the Rinda tool. In the meantime, I ran accross this bulletin from Mercury Marine that may shed some light on the issue. Of note, there seems to be an issue with the 50 AMP yellow flag circuit that has been related to the misfires. I'm not sure why that would do it but my engine has one of these yellow flag type CBs at least. I found it sort of tripped when the trim wouldn't work. If the new style button is cheap, I may swap it out just for fun. The bulletin says that the engine at either 2,000 or 4,000 RPM is st it's most stressful and the 50 AMP CB can cause it to misfire somehow. Just a though for those of us with this issue. To be clear, I haven't tried swapping the CB out but may. If I do, I will let you all know.

That, my friend, is some good info I have not seen before.

 

[Brite Idea]

I've been experiencing the same annoying alarms on my VV since last year. It finally got to the point where I wasn't getting charging voltage out of the starboard alternator. It has finally been diagnose as the stupid little circuit breaker with the yellow flag. I had to reset it and now it's working but my mechanic ordered two since the ones with the yellow flag are know to cause misfires. Mine was diagnosed easily because it was tripped and I was still able to start the boat and that's not how it's supposed to work.

 

[Chris Lovlecae]

Ok...I really do think my engine is misfiring. O2 sensor error and a sulfur sort of smell after coming to idle. I'm perplexed because I get 5,200-5,300 RPM WOT. If I had a cylinder misfiring I can't believe I'd see that. I did notice an odd sort of rattling sound when the RPM is between 3,500 and 4,000. Above 4,000 it goes away and the engine seems to run like a bat-out-of-hell! Could I have a stuck open fuel injector? What are the symptoms of that?

My son and I were out two days ago driving across the river to get some gas. Since we were just puttsing around, I kept the throttle under 3,500 just to save fuel (around 3,200 seems to be best fuel economy for me) and I never smelled the sulfur smell. I seem to get it going above 3,500.

Any thoughts from the experts here? Mercruiser mechanics seem to be a rare breed in my neck of the woods with a one month waiting list.

Thanks for any help!

 

[Skyman2112]

The misfires the computer registers are imperceptable. Once it reaches a certain percentage of the total its considered maximum number of misfires exceeded. This level was set very low on first gen catalyst motors in order to prevent damage to the the cats. My 2011 377mag had the same problem. I ended up taking out the PCM and giving it to the merc rep at my local boat repair shop. They updated the software to what im told is a newer version of the software with a less conservative misfire allowance and the alarm never went off again.

 

[Chris Lovlecae]

Thanks, Skyman! I actually do think the engine is misfiring based on the secondary indications. It doesn't happen all the time but it for sure is. Dropped it off at the shop yesterday. They said they'll get to it next week. Fingers crossed it's something small. I will post what it was for the historical record!

 

[Chris Lovlecae]

The saga continues...

I'm on the third week of the shop having my boat while my summer slips away! They said they could get to it the first week. So the got to it late in the second week. They hooked the computer up to the PCM and said that the PCM had logged the engine misfire. In addition, there was an old O2 sensor error and that both banks were running rich. They hook a fuel pressure guage to the fuel manifold to make sure the pressure pressure regulator wasn't bad and it wasn't. So they took it out for a sea trial and.....

...nothing. They couldn't find anything wrong besides the trim sensor which I knew was broken. Engine didn't misfire...no nothing!

So I told them that if I pick it up and take it out, you know I will have a misfire within 5 minutes of getting underway. So I asked them to give it another go. Which they did today and WALLA! Misfire, Baby! I suppose I should be happy since they saw it so they know I'm not crazy (even though it's there, clear as crystal in the PCM data to paraphrase Willie Wanka). I was told that they had to contact Mercury Marine for advice on what to do since I don't think there is a smoking gun here.

When was driving it over to the boat ramp, I was getting 5,200 to 5,300 RPM at about 46 MPH when I had a quick cut out followed by a short beep. Now this was at speed so the noise of the wind and engine kind of drowned it out. The cut out lasted maybe a 10th of a second and it happened three times at WOT within about 2 minutes. Now I've had it at WOT a bunch and never saw that before. I checked the Smart Craft guage and there was nothing new.

Below WOT it didn't happen.

Now, one of the techs said that the engine has a RPM limiter that would trigger if the engine went above a set amount and that limit would manifest as a misfire. That seems a bit hokie to me. I can't find any specs on what the engine RPM limit is and I'm not a mechanic so there you go!

The good news is Mercury Marine customer service has been very good to me when it comes to information when I've requested it so how much more will they be with a trained mechanic who is certified to service their engines. Additionally, my engine type has been around for at least 12 years so I'd assume Mercury Marine has a large database of misfire troubles and what was done to fix them...at least I'm hoping they do.

I wonder if it's similar to other people's issues where there is a programming error with the PCM/ECM (Mercury says my engine has a PCM). Mercury sends an update that is loaded on the PCM and BAM...all better!

I'm not sure anyone is reading this but it is cathartic for me so I'm writing this as a distraction from the fact that beautiful boating days are going to waste and at the end of this is undoubtedly a large bill for all the work the marina did.

Oh well...it's only money and you can't take it with you when you go!

 

[Brite Idea]

Mercruiser has this:
Service Bulletin Bulletin No. 2011-11R2 OEM No. 2011-07R2
The fault indicates that the PCM detected excessive cylinder misfire. The PCM can detect cylinder misfire before a technician can detect it. Since the misfiring is not detectable by the technician in most cases, correcting this fault can be very difficult for those unfamiliar with diagnosing emissions‑related systems. NOTE: The "Cylinder Misfire Detection" program runs continuously, regardless of RPM, load, and fuel control mode.
all about misfires.

I have a 2010 twin 5.0 Bravo III and don't touch WOT because more than once it has recorded a misfire. The dreaded Smart Craft then beeps at you endlessly until you have it reset. The draw back is that you have to go to the dealer/mechanic so they can clear it because it's a hard code.

 

[Espos4]

The saga continues...

I'm on the third week of the shop having my boat while my summer slips away! They said they could get to it the first week. So the got to it late in the second week. They hooked the computer up to the PCM and said that the PCM had logged the engine misfire. In addition, there was an old O2 sensor error and that both banks were running rich. They hook a fuel pressure guage to the fuel manifold to make sure the pressure pressure regulator wasn't bad and it wasn't. So they took it out for a sea trial and.....

...nothing. They couldn't find anything wrong besides the trim sensor which I knew was broken. Engine didn't misfire...no nothing!

So I told them that if I pick it up and take it out, you know I will have a misfire within 5 minutes of getting underway. So I asked them to give it another go. Which they did today and WALLA! Misfire, Baby! I suppose I should be happy since they saw it so they know I'm not crazy (even though it's there, clear as crystal in the PCM data to paraphrase Willie Wanka). I was told that they had to contact Mercury Marine for advice on what to do since I don't think there is a smoking gun here.

When was driving it over to the boat ramp, I was getting 5,200 to 5,300 RPM at about 46 MPH when I had a quick cut out followed by a short beep. Now this was at speed so the noise of the wind and engine kind of drowned it out. The cut out lasted maybe a 10th of a second and it happened three times at WOT within about 2 minutes. Now I've had it at WOT a bunch and never saw that before. I checked the Smart Craft guage and there was nothing new.

Below WOT it didn't happen.

Now, one of the techs said that the engine has a RPM limiter that would trigger if the engine went above a set amount and that limit would manifest as a misfire. That seems a bit hokie to me. I can't find any specs on what the engine RPM limit is and I'm not a mechanic so there you go!

The good news is Mercury Marine customer service has been very good to me when it comes to information when I've requested it so how much more will they be with a trained mechanic who is certified to service their engines. Additionally, my engine type has been around for at least 12 years so I'd assume Mercury Marine has a large database of misfire troubles and what was done to fix them...at least I'm hoping they do.

I wonder if it's similar to other people's issues where there is a programming error with the PCM/ECM (Mercury says my engine has a PCM). Mercury sends an update that is loaded on the PCM and BAM...all better!

I'm not sure anyone is reading this but it is cathartic for me so I'm writing this as a distraction from the fact that beautiful boating days are going to waste and at the end of this is undoubtedly a large bill for all the work the marina did.

Oh well...it's only money and you can't take it with you when you go!

Wait……. You only notice this at wide open throttle??

You are probably hitting the rev limiter, the ECM cuts rpm by dropping spark or fuel or both, the ECM sees a misfire and sets a code.

Resolution: stay below 5,000 rpm and enjoy the boat.

 

[techmitch]

The saga continues...

I'm on the third week of the shop having my boat while my summer slips away! They said they could get to it the first week. So the got to it late in the second week. They hooked the computer up to the PCM and said that the PCM had logged the engine misfire. In addition, there was an old O2 sensor error and that both banks were running rich. They hook a fuel pressure guage to the fuel manifold to make sure the pressure pressure regulator wasn't bad and it wasn't. So they took it out for a sea trial and.....

...nothing. They couldn't find anything wrong besides the trim sensor which I knew was broken. Engine didn't misfire...no nothing!

So I told them that if I pick it up and take it out, you know I will have a misfire within 5 minutes of getting underway. So I asked them to give it another go. Which they did today and WALLA! Misfire, Baby! I suppose I should be happy since they saw it so they know I'm not crazy (even though it's there, clear as crystal in the PCM data to paraphrase Willie Wanka). I was told that they had to contact Mercury Marine for advice on what to do since I don't think there is a smoking gun here.

When was driving it over to the boat ramp, I was getting 5,200 to 5,300 RPM at about 46 MPH when I had a quick cut out followed by a short beep. Now this was at speed so the noise of the wind and engine kind of drowned it out. The cut out lasted maybe a 10th of a second and it happened three times at WOT within about 2 minutes. Now I've had it at WOT a bunch and never saw that before. I checked the Smart Craft guage and there was nothing new.

Below WOT it didn't happen.

Now, one of the techs said that the engine has a RPM limiter that would trigger if the engine went above a set amount and that limit would manifest as a misfire. That seems a bit hokie to me. I can't find any specs on what the engine RPM limit is and I'm not a mechanic so there you go!

The good news is Mercury Marine customer service has been very good to me when it comes to information when I've requested it so how much more will they be with a trained mechanic who is certified to service their engines. Additionally, my engine type has been around for at least 12 years so I'd assume Mercury Marine has a large database of misfire troubles and what was done to fix them...at least I'm hoping they do.

I wonder if it's similar to other people's issues where there is a programming error with the PCM/ECM (Mercury says my engine has a PCM). Mercury sends an update that is loaded on the PCM and BAM...all better!

I'm not sure anyone is reading this but it is cathartic for me so I'm writing this as a distraction from the fact that beautiful boating days are going to waste and at the end of this is undoubtedly a large bill for all the work the marina did.

Oh well...it's only money and you can't take it with you when you go!

Wait……. You only notice this at wide open throttle??

You are probably hitting the rev limiter, the ECM cuts rpm by dropping spark or fuel or both, the ECM sees a misfire and sets a code.

Resolution: stay below 5,000 rpm and enjoy the boat.

It should set an eng. over speed code if you hit the rev limiter too many times not a misfire code. Possibly a code 19.

 

[Chris Lovlecae]

Hmmm...so there is truth to the Rev limiter? Is 5k the limit? I can easily get over that at WOT with a little trim. Highest I saw was 5,300 RPM. My engine is DTS. Seems like there might be a setting that is messed up if the throttle allows that.

My shop said they are talking with Mercury Marine to get some help. They seem perplexed by this. Probably what do they need to adjust since the PCM is allowing the engine to get that high if 5k is the limit. I'm hoping this thread will end at a solution in my case. At least others can learn from my journey.

What would be causing the engine to run rich? I spent an afternoon towing some tubers and sometimes, when I'd stop, the people sitting in the back noticed an egg, sulfur sort of odor. Would the PCM cause a rich running engine if there's a misfire?

 

[Brite Idea]

I think Espos has it right you're hitting the rev limiter which I think on your engine is 5150rpms. You could just stay under that or play with a little more pitch in the props? I'm guessing you have a Bravo III? What props are you turning?

 

[Chris Lovlecae]

I do have a Bravo III. I think 22.4 is stamped somewhere on them but will have to see if I have any pictures of the prop to tell. I believe the props are stock from whatever came with the boat. So what's the standard that came with 2011 Sea Ray 260 Sundecks? I have a 4 bladed that's just before a 3 bladed prop. That's an option to change the pitch to control RPM perhaps. I'm surprised that the PCM doesn't just limit RPM so WOT is at or just below the limit. I'm getting near 5,000 at WOT with the trim all the way down. I give it a few shots of up trim, RPM increase a 200-300, the bow rises a smidge and I get about 3-5 MPH increase. It hadn't occurred to me that there be an issue hear but I will keep it below 5,000 from here on in based on hwat the shop tells me.