Just got off the phone with my dealers service manager. Her informed me that Mercuiser is providing an update to the ECM to eliminate the Black Transom.

Anybody here the same or have any more information?

A friend of mine had the same problem,got a new ECM from his dealer(updated from Mercury)works great!No more black transom. Bob

Assume your talking about soot?
My 375HP was terrible for first 25 hrs..somewhat better
now, but still soots..Is the new ECM for Mags and HOs?

My 496HO cleaned up after 25 or so hours as well.

Should we be expecting the transom to stay perfectly clean.

Much better than it was in the begining,
but still get it every time I go out. I clean it
with simple green. I warm my boat at 1200
instead of idle, seems to help, I believe its
getting too much fuel when cold and the higher
rpm seems to burn it. This was suggested by
a tech. I wonder if I'm too late to get mine done.
John

I also had the update done, no more black soot on transom. The motor is a 496 HO. I sent it on Monday and got it back on Wednesday.

Wheres it located and how do u replace it??I guess u have to remove old one first?

My friends 496 was a mag.He almost sold the boat because of the soot.*****ed one more time to his dealer and "presto-chango" new ECM, no more soot!Mercury said he'd be happy and he is. Bob

What year or ser# engines or ECM's does this apply to?...If there is a leaner running update, I want to know about it! I'll take any crispness I can get, any any RPM

More info please, Snopro did you send the ECU to Merc. yourself or did the dealer. I will get mine out tomorrow if I can. I just got done cleaning again from the weekend and the soot is terrible. 35 hours on it now.