mats

Advancing the ignition too much should overheat the engine. 40 degrees sounds way out to me.What does the starboard engine have in the 3000-5000 range? The ECM SW is a prime suspect. unfortunately I canīt read your scan tool data but I assume they show reasonable and similar values between the engines.

mats

I continue to think out loud here. IF the ECM checks out OK then the next step would be to check all the sensors. On the scan data you can see if the TP, MAP, IAT, IAC and ECT deliver reasonable values(and similar in between the engines).Further, the knock sensor is especially important since it has a key role in limiting the advance from getting too high. In order to check that one you have to check the input reference from the ECM to the sensor with a DVOM and, if that checks out, swap the sensors between the engines and see if the advance curve becomes normal on the port engine and/or the problem moves over to the starboard engine.

On marine mechanics, I guess it is almost as tough in Oklahoma as it is here in Stockholm, Sweden. Fortunately there are good books .......

blown formula

I guess I need to find a Merc manual for all the test/calibration proceedures....???? where??

mats

Here for example; www.motocom.com/marine/6
I think you can buy them at West Marine also.

mats

BTW, Amazon.com is cheaper. They have the Clymer Merc 95-97 manual

blown formula

Thanks Mat.....

I really thought there would be more "input" from others also....
so I guess EFI really is a strange bird to most everyone!

mats

I agree the EFI is tricky to troubleshoot. However, having two identical engines and swapping things between them in a structured way and observe the result is basically all you need to figure out what is wrong.

blown formula

What's happened to dennis moore??? I fully expected him to weigh in on this problem????????
Dennis?????

Turbojack

Blown- By the time you learn about this boat & all the things you learned from the last one you are going to be one hell of a mechanic.

blown formula

More people end up in "the house" so to speak with Jack Nickleson (remember the movie???) than become good mechanics!! Unfortunately, I am now having to go back to work full time & 100 miles away from the boat!! Only on weekends to fight this thing & I still want to play some (the wife insists on it!).

Pantera- My timing IS set to 28* on both engines, just one of them indicates on the scan tool that the spark advance is low at 19-21* when the crank is showing 28*, Then a 3000 rpm, both engines are now at 40*+ !! Az Spd has my ECM's & I have been trying to reach Shoffner all week with no luck..... I gotta get a life!!