F300 Port Bank not firing at idle

[Travis78]

I am quite lost with this one, I feel like I have tried everything...I would really appreciate your thoughts.

Have twin F300's on a 38' boat, single fuel tank, independent filters.
Starboard engine with ~900hrs runs great, Port engine with 1700hrs runs not so great

No trouble starting, but it is quickly obvious that it is not running on all cylinders, the engine is physically shaking considerably more then its twin. I learned from disconnecting coils that only the right bank is firing.
Also, lots of noise when you put it in gear, sounds like the gears are slapping in and out of contact due to rough idle, however, add throttle and she runs fine, all the cylinders starting working above 2500rpm and during sea trials, makes all the power you would expect.

Compression test showed roughly 10 bar across all cylinders.
Y-DIS shows no errors, all voltages for shift position sensors are perfect, no indication that computer is doing this on purpose. (also no errors recording misfires, is this beyond the Yamaha's self-diagnostics?)

Pulled and tested both coils and injectors on left side of engine, coils are firing, injectors are producing a nice mist as expected.

Lower unit was removed (with great force and destruction I might add), no sign of melted exhaust housing, but really hard to see from the bottom, engine still only ran on 3 cylinders

List of things changed from other working engine:
Plugs
Coils
Injectors (the whole rail)
Changed timing belt and rechecked timing
ECM( Computer) at same time, switched to opposite Throttle Lever (DEC) on console to avoid needing to reset DEC with computer
VCT (long shot but hey, why not?)
Complete powerhead wiring harness
throttle body
all three cam sensors
with great difficulty, wired up both the shift position switch and shift actuator from starboard engine to port engine without removing either.

last things to try tomorrow, swap pulser coil and flywheel.
will also try running off small dingy tank of gas just to eliminate that.
maybe change high pressure pump just to eliminate it completely?

It feels ridiculous, but might change head/cams from other blown powerhead

Any ideas?

Thanks

Travis

[fairdeal]

last things to try tomorrow, swap pulser coil and flywheel.

will also try running off small dingy tank of gas just to eliminate that.

maybe change high pressure pump just to eliminate it completely?

its an amazing story - going to take me some time to absorb


but as for your planned next steps - (as with many you've already taken)


how could those possibly affect only "one bank" - but not the other?

[rodbolt17]

and that is the difference in training and trouble shooting and splatter gunning.
nothing on that F motor fires or controls one bank.
myself I would like to see a running screen shot on YDS.

[ausnoelm]

Wholesale parts swapping can also result in other introduced faults, even in the good motor! You said you have no spark, why swap injectors??

[Travis78]

Good Night,
Thanks for the replies,

My background is heavy equipment so please excuse the steps and the order I've taken, what's done is done...

Fairdeal:
Sometimes when you get stumped by a problem you start to come up with some crazy rationale, for instance, of how maybe the DST got stuck fully retarded and that somehow makes sense in your sun soaked head while trying to figure out what should have been a simple problem. I have lots of time, and it honestly doesn't bother me if I have to swap every single last part of this engine to figure out what is going on, but running out of things to swap..

Rodbolt17:
I agree with you completely regarding splatter gun approach, but well, see above
I've attached the log files from the Y-DIS (hopefully without upsetting the forum, I removed the cvs and ods appendages) I am not sure how to get the data logger to work, I would have liked to see some data at higher rpm and in gear, I keep getting a "no data available" error in Y-DIS, I'll look for the manual tomorrow. The .ods file should open fine in excel or open office when the .txt has been removed.

Ausnoelm: Wholesale parts swapping lead me to find out how dirty the throttle valve was on this engine, swapping throttle valves really made a noticeable difference in how the "good" engine was running..so that's one small thing that's been fixed.
I'm sorry, I should have been more clear in the description, at idle I have spark, gas and even compression, but no combustion in those cylinders, I've checked/changed timing, plugs, coils, injectors, wiring harness and computer, nothing makes a difference, until your over about 2500rpm, then it smooths out and runs fine.

Thanks for your thoughts, they are really appreciated.

-travis

Screen shots of log files:
https://imgur.com/a/1vlZn

[rodbolt17]

well that opens jibberish on my machine.
how have you determined a no spark issue?
did you use a Kv tester?
did you use a peak reading voltmeter?

[Travis78]

Sorry, just looked at the screen shot, the engine isn't even running. I'll try again and repost.

I'm very limited by tools here, even a spark gap tester is a tall order.

I have ruled out a spark issue by changing plugs, coil and harness and computer from a good running engine. Even running separate ground and 12v supply directly to coils.

Thanks
travis

[ausnoelm]

Let's get something clear here, are you saying you have no spark on one bank, or one bank is not firing, as in, has spark, but not producing a "power" stroke? I understood there was no spark at all on one bank, but rereading, it kind of doesn't really say that.

[boscoe99]

Let's get something clear here, are you saying you have no spark on one bank, or one bank is not firing, as in, has spark, but not producing a "power" stroke? I understood there was no spark at all on one bank, but rereading, it kind of doesn't really say that.

I read it the same. He said when he disconnects the coils on one side there is no change in the poor performance of the motor. Leading one to possibly believe that the power/ground source to the ignition coils on that side of the motor is compromised. Not likely but what else could it be? It is the only thing common to the coils. But there are three independent power feed/ground wires to the coils from a junction box. Not sure how all three would fail at the same time. Extremely unlikely. He never said whether he had voltage (or a ground) to the coils when he determined that all three were not firing.

[fairdeal]

start of an epidemic?

post this afternoon on another forum, in this case the starboard motor is the problem, port motor is OK:

Motor is a 2010 F300 with approx 1,200 hours. Issue started last week while running at approx 4300 RPM, started to lose RPM’s on stbd motor. Slowed down to idle and the motor had shut off. Struggled to idle after restarting and come to find out only running on 3 cylinders (one side).

Yes 3 on one side. Pulled plug wires on each. Also did an injector test and heard each clicking.

Troubleshooting so far:
Changed fuel/water seperator -clean
Changed primary filter-clean
Plugged into computer-no codes
Swapped stator with port motor-no fix
Swapped ECM’s with port motor-no fix, port motor ran fine.
Swapped injectors-no fix
Confirmed spark on all plugs
Replaced 3 plugs on non running side

[boscoe99]

I can see rodnut now saying "don't tell what it is doing, when it is doing it, what you have done or not done, or what you think the problem is. Just give me the keys and leave the boat here".

[boscoe99]

start of an epidemic?

post this afternoon on another forum, in this case the starboard motor is the problem, port motor is OK:

Motor is a 2010 F300 with approx 1,200 hours. Issue started last week while running at approx 4300 RPM, started to lose RPM’s on stbd motor. Slowed down to idle and the motor had shut off. Struggled to idle after restarting and come to find out only running on 3 cylinders (one side).

Yes 3 on one side. Pulled plug wires on each. Also did an injector test and heard each clicking.

Troubleshooting so far:
Changed fuel/water seperator -clean
Changed primary filter-clean
Plugged into computer-no codes
Swapped stator with port motor-no fix
Swapped ECM’s with port motor-no fix, port motor ran fine.
Swapped injectors-no fix
Confirmed spark on all plugs
Replaced 3 plugs on non running side

I hope he replaced all of the flywheel bolts with new ones when the flywheel was off to get access to the stator assembly.

But now it seems we do have spark to all plugs. Why change plugs on the non running side if they all have spark. Hmmm.

[Travis78]

One bank is not making any power. It has fuel, it has spark, it has compression. Only thing left that I can think of is valve timing ?

I changed plugs, because I've met engines that show a spark outside of the combustion chamber but to fail when installed in the head.

Above problem sounds similar, but this engine makes power above 2500rpm, and has no trouble starting.

Reused flywheel bolts.

I will make another attempt to download a proper log of the engine with y-dis tomorrow.

Thanks for the comments,

Travis

[panasonic]

If you put a brand new set of plugs in the engine and then ran it at low RPM for a short period of time...running rough as it is doing. Pull the plugs and compare the left bank to right and see how they look? They should look quite different if those cylinders are not working.

Maybe you have already done this, but if not, something you can try. Post a picture of the plugs for all to see.They may help to tell the tale.

[Inmyopinion]

You may want to use a scope and check the cam crank correlation on each cylinder bank to make sure they are in the correct sync. On some fords engines the CVT solenoids and or cam phaser will fail causing that cylinder bank not to advance the valve timing as needed. (I know this is an outboard but they use the same/similar design)When then engine is above 2500 rpm oil volume/pressure may allow the sticking solenoid to operate. Rodbolt probbally will reply because he has seen a lot of these motors and their common failure modes.