PA.WOODCHUCK

Old school and cheap check
1- check plug wire resistance with digital meter
2- water in spray bottle and mist wires and see if engine starts missing.

JohanSweden

Thank you all for the advices, when im thinking of it.. I may have seen it arcing somewhere on the engine one time last year when it was darker in the engine compartment.

Definitly gonna check the spark plugs..!
What resistance should the wires have?

No beeping alarm from the engine.

speicher lane

Just one thing to add to this, run the blowers and double check there is no fuel leak...if the wires are bad there will be an open arc.

I wouldn't recommend that you are standing in the engine compartment, standing in the water mist, with shorts(bare skin) when you find a bad wire. I know a tech that had this happen and now he doesn't mist test, just recommends a new wire set every 2-3 years. He had to have sprayed a lot of mist expecting nothing but to this day if he gets a bit cocky, someone in the group will ask how to test a wire set on the engine - LOL

SB

iTrader: (1)

2-3 years ? Really ? All the more reason to reduce gaps to a more normal .045 on these app’s with coil and wire burning ridiculous .060” gaps.

JohanSweden

I started with measure the spark plug cables.
With my multimeter at 20K I got these numbers, starting on port side and from the front of the engine.

Port side
1 - 2.37
2 - 3.04
3 - 3.03
4 - 2.37

Starboard side
1 - 2.38
2 - 3.06
3 - 3.01
4 - 2.35

JohanSweden

Dont know if the resistance is good or bad.
If the resistance is good, can it still be some fault in the spark plug cables?

Or is it one of the eight ignition coils that can cause the problem?

boatnt

iTrader: (1)

plug wires are fine, remove and inspect spark plugs see if one is fouled

Rookie

iTrader: (4)

MAP sensor going out.

JohanSweden

Im looking at the spark plugs today. See if theres someone fouled.

Okey, you think so?
Is This a common problem with the MAP sensor?

JohanSweden

Here is some pictures of all the spark plugs in order. Starting from the back of engine.
Starboard plugs at the left, port plugs at the right.

Back of engine

8 7
6 5
4 3
2 1

Front of engine

In my eyes there is several plugs that dont look good, but the first spark plug on port side (#7 cylinder?) dont look good at all... almost completely black...

what do you guys think?

Also, when I turned the engine by hand to look at the valves opening and closing, the exhaust valve at cylinder #5 doesnt close all the way.
It first didnt move at all. But when I turned the engine a couple of turns it started to move and close (but didnt close all the way)...