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.

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 .......

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

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

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

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!

Disconnect the lead to the knock sensor, the ECM will go to a preset value.

Timing is way too high. I'm running 28 - 30 degrees.

The following are links to what I went through and tried, perhaps some or hopefully one idea will help you, even though we had disimilar problems. Most of this is ECM troubleshooting:

http://www.offshoreonly.com/forums/s...threadid=48133


http://offshoreonly.com/forums/showt...threadid=47022

I'll check back often and see what i can do to help!!

Good Luck!

Kirk

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.

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

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.