Marine Power 6L Problems

[cpropes2005]

I think my other thread got lost so I figured I would repost it. I am having a problem with my 6l marine power where it will lose power as it passes 2000 rpm and then immediately recover. It is at the dealership now and they said they read the codes off of it and got a can phaser code. Anyone have any insight on what that might be? The engine is basically new and only has 14 hours on it.

[cpropes2005]

Not sure how to edit posts on the new forum. They said it was a cam phaser code not can phaser. Also, I changed the fuel filters, impeller, and pedal position sensor befor taking it in to the dealer so I don't think it is those things. I also have good fuel pressure at the fuel rail.

I am a little worried because the dealer has a call in to Marine Power to try and get more info on the code but he was talking like it could mean pulling the motor to get the cam shaft out which could be months out on lead time this time of the year plus $$.

[cpropes2005]

I hate mechanical threads that dont have resolutions so here is an update on my issues. Long story short is that it looks like the problem was dirty oil. The variable valve timing system on the 6.0's works by using a little electric actuator to open and close a small valve assembly. Based on the position of that valve pressurized engine oil is directed into different cavities in the cam phaser assembly and the pressure differential between the cavities controls the position of the cam relative to the sprocket. Anyways, these are small little valves and it looks like the old oil was gumming up the system causing my issues. They said oil was really bad which is interesting because the motor only has 14 hours on it but two oil changes to clean out all of the bad stuff and they say it is running much better with no codes. I am taking it out this weekend so fingers crossed that none of the issues come back and I will just have to keep a really close eye on my oil in the future.

[dom w. forte]

My question is who put the engine in and what caused the oil to get that dirty, what did they mean by dirty, debree , chunks ?

[BLK Z1 Nakomis]

This is a silly question but assuming you change oil seasonally even with the low hrs correct

[cpropes2005]

I dont think there was any debri or chunks in the oil that they could see. I think it was just really dark and I am hoping that is just from the boat sitting for awhile. I bought the boat in December of 2012 but the best I can tell the motor was put in sometime in 2010 and it obviously wasnt used much after that because of the low hours. It was also obvious that the oil hadnt been changed since the motor install because they installed a long filter when they put the motor in and it was resting on the bottom of the hull so the mechanic had to cut it off and replace it with a shorter filter so that I can actually unscrew it to do oil changes.

I always change the oil in my boats at the beginning of every season. I just hadnt gotten to it on the new boat yet beacause I was trying to resolve the symtoms I was having and before learning about how the vvt system works I never would have thought it could have been caused by old oil. Live and learn.

[cpropes2005]

Well unfortunately for me the saga continues on my boat. I had a feeling that changing the oil was too easy of a fix but I was assured that it was lake tested twice and was running great. Well, I had it out twice over the weekend and it ran like crap both times so I think I just paid for the worlds most expensive oil change and no resolution to my issues.

The first time out it immediately had the issue of losing power as it passes 2000 RPM and then recovering and going on its way. The second time out after idling for a minute or so through a no wake zone it began idling very rough and eventually died. It would restart each time and on about the 4th restart it cleared up completely and ran fine for the rest of the day. The mechanic thinks that it is all related to the variable valve timing and the cam phaser assembly and I tend to agree. Any thoughts on what the next move should be?

I have considered replacing the camshaft and crankshaft position sensors. As I understand it the ECM works in concert with these sensors to tell the cam phaser valve where it needs to be so maybe replacing them would help?

[Ewok]

Did you also clean the fuel system? If it sat for 2 years without and oil change then I bet the gas went bad and potentially clogged up the injectors and the rest of the lines. Especially since you said the second time it bogged down but eventually ran fine for the day. I would run some seafoam with the next tank of gas, then change the fuel filters after that tank and see if that helps. It might not be the total fix but it can't hurt either.

[cpropes2005]

My original thread got deleted in the move to the new site some of the info was lost but yeah I was originally thinking fuel as well. I changed both fuel filters, checked the gas for water, and checked fuel pressure with no luck so that is when I took it in and we started down the cam phaser path. They said it had 7 or 8 stored codes but the one for the cam phaser was the only one that came back after they initially reset it. I need to find out what the actual code numbers are.

[SBM1234]

I would think that your mechanic has probably checked all of these, but this is where I would start.

Spark Plugs and Plug Wires
Fuel Pressure
Check the timing


At 2k rpm it is entering the power band for that motor so if there is predetonation, it will probably start right about there. I am thinking that the ECM senses it at about 2K rpm, adjusts the timing accordingly, and then it is able to pick back up. The cam phaser and knock sensor codes kind of elude to that being the problem.

Hope it helps and good luck!

[cpropes2005]

I dont know if they did check the plugs and wires but that is something easy I can do.

Assuming it is the timing like SBM mentioned anyone know what the likely fix would be? New cam phaser? Reflash the ECM?

[dom w. forte]

Well unfortunately for me the saga continues on my boat. I had a feeling that changing the oil was too easy of a fix but I was assured that it was lake tested twice and was running great. Well, I had it out twice over the weekend and it ran like crap both times so I think I just paid for the worlds most expensive oil change and no resolution to my issues.

The first time out it immediately had the issue of losing power as it passes 2000 RPM and then recovering and going on its way. The second time out after idling for a minute or so through a no wake zone it began idling very rough and eventually died. It would restart each time and on about the 4th restart it cleared up completely and ran fine for the rest of the day. The mechanic thinks that it is all related to the variable valve timing and the cam phaser assembly and I tend to agree. Any thoughts on what the next move should be?

I have considered replacing the camshaft and crankshaft position sensors. As I understand it the ECM works in concert with these sensors to tell the cam phaser valve where it needs to be so maybe replacing them would help?

To me the cam phaser would have nothing to do with a long idle and just dieing , that sounds like fuel purculation a common 6.0l problem , I would examine all fuel line routing since engine swap and all fuel cooling systems to make sure nothing was altered during swap , if all eles checks ok watch your temp., when the engine acts up, and does it act from the start or after fully warmed?

[ChrisBarnes05-12-84]

I had similar problems with my 5.7 Marine power engine before. After a bunch of trouble shooting i opened up the cap and the rotor bug was loose. Put the screw back in and it ran perfect. I'm not exactly sure what the 6L is like or if its even the same. But my boat would run good until it started winding at a higher rpm and then it would start mis firing. I'm sure it looked like the 4th of July down inside the cap. Another thing I would check is the MAP sensor. If its bad it will make your engine run like S@!#. Hope some of this helps.

[cpropes2005]

So it has been awhile since I posted this but I got a scanner tool and am trying to process some new information so I figured I would revive this thread and see if I could get some input.

Just as a refresher the issue I am having is that on acceleration at exactly 2000 rpm I will get a momentary “blip” or loss of power before the engine recovers and goes on accelerating as usual. The problem is intermittent but probably happens at least 50% of the time.

I was able to log data while reving the engine in neutral and getting the “blip” to occur at 2000 rpm. I am working on figuring out how to plot the log data but I have observed a couple of interesting things from watching the playback. The first thing I noticed was the injector pulse width for both banks jumps from about 5ms to 13ms the instant the blip occurs. After doing a little research it sounded like the main variables controlling pulse width are RPM and manifold pressure. So next I replayed the log and sure enough the MAP sensor output jumps from about 30 kPa to almost 70 kPa the moment the blip occurs and then comes back to down to the 30 range as I continue to accelerate. The question I have is this just my MAP sensor going bad or could there be something else going on that could actually cause the manifold pressure to spike like that at the exact same rpm every time? I am leaning towards just replacing the sensor and seeing if that solves my problem but I wanted to keep this thread up to date since I know at least a few others have had similar problems.

[cpropes2005]

I took another look at the scan log and the cam angle jumps about 50 degrees at the exact moment of the hesitation which leads back to the original diagnosis from the dealership of a CAM phaser. The jump in cam position would explain the sudden increase in manifold pressure so maybe it isn't a map sensor issue. Being that it is clearly still functioning though I am still not convinced that the actual CAM phaser is bad vs some other sensor sending it a bad signal. Anybody have any ideas on what could cause the cam position to jump so dramatically like that when I hit a certain rpm?