DF60A runs on 2 sylinders up to 3000rpm

[EasyE6]

Hi, im new here and come from Norway so excuse my bad writing.
I have a 2010 DF60A that have been under water. (Saltwater)
My problem is that it is running on 2 sylinders from idle to aprox. 3000rpm. It is giving fault code 3-2 map sensor2.
I have changed compleete engine cabelkit, iac valve, throttle body ink map, tps and air tempsensor and sparkplugs.
I have tried swapping the ecu (from another motor)with no luck, cross swapped ignition coils and injectors but the 3rd sylinder will not run.
If i disconect the 3rd coil and or injector there is no difference in engine responce up to 3000rpm (upper limit in neutral)
Tried it on the water today and it runs perfectly from 3000-6200 rpm.
What could be wrong?? Please help:-)

[redlowrey]

That code is pressure detect, make sure the little hole in the inlet manifold is not blocked other wise the ecu cannot read the changes in manifold vacuum. What colour was the spark plug porcilane at the electrode on number three. Have you done some basic checks eg compression, air leaks on the inlet manifold on number three, valve clearance, it could even be a slightly blocked injector.

[EasyE6]

Thanks for reply!
Yes, i have checked all i can think about. Compression is good, the trottle body whit the sensors are new, manifold looks good. The spark plugs are getting black, not wet all three. Strange when i dont think it is running on sylinder 3. I have swithed places on both coils and injectors and it is allways syl 3 that is not running. If i disconect coils or injectors from syl 1 or2 it almost stops but on syl 3 no diffrence. For info i found some water in the vapor earlier. Could it be a sylinder leakage from piston rings or could it be any of the valves? How do i check valve clearance? Do i have to split the engine? Something is playing with me....What could be working well over 3000rpm but not under?
Hard for me to find out when im on muffs.

[redlowrey]

The black plugs tell me it is running too rich, make sure that the little hole in the manifold where the map sensor bolts on is not blocked.

[redlowrey]

I missed something usually when water gets into a cyl there is a tell tale sign on the plug or a bit of rust

[EasyE6]

The boat it is sitting on went down last fall.
I bought it as a project. I changed all the electrics and spark plugs in october and put away for the winter. I cant remember how the spark plugs looked like, but the new ones are getting black. On this motor the map sensor are sitting on the throttle body from factory and its new. I dont think air amount is the problem because then it should affect all three sylinders. I think the fault 3-2 is coming because sylinder 3 is not running and therefor the map sensor see fault. Does this make sense?

[redlowrey]

Can you do this test, run the engine at 2000rpm for a few minutes then shut it down. and remove the plugs and note their position and colour and if no3 is wet or dry or has signs of water on it.

[EasyE6]

After the test the sparkplug is black and a littlebit wet. (Not water)
Another thing, i tried to start it with only plug and injector 3 connected. Guess what... it started. After that i swithed to nr2 and the rpm was about double as high. So if i run on only sylinder 1 or2 at about 3000rpm and swith to nr. 3 the rpm will go down to about 1500 or so. What could do this? Is it timing, defect valve. Is it possible that nr 3 is getting only half of the spark it should?

[redlowrey]

If number three works on its own, and then when you have two cyls working and you connect number thee up the rpm drops, it sound like its dumping exhaust gas into the other cyls. The only way that can happen is through the head gasket or a tight inlet valve, did you do a compression test. Has this engine been pulled down by some one after it sunk.

[EasyE6]

Sorry, i did not explain wery well.
If i run only sylinder 1 or 2 at 3000rpm and change to only sylinder 3 the rpm drops to about half.

[EasyE6]

I have now found the fault...
Both exaust valve springs on sylinder 3 are broken in two.
How could this happen??

[EasyE6]

Engine is now repaird.
Thanks redlowry for taking time to answer.