Pwraddr

Mine were redone by merc....I find the soot VERY fuel dependent. If I run ethanol free, virtually nothing.

BajaDan

iTrader: (2)

That's very interesting Pwraddr. I have a 2001 (very early) 496 mag that sooted quite a bit. I sent the PCM back to Merc for an update (reflash) which they did. It totally eliminated the soot but also cost me 4 mph. Since I rarely go wide open it was a satisfactory tradeoff for me but I do miss those 4 mph! I never tried ethanol free fuel as it is not readily availble here. That is an interesting thought to consider though as the early PCM's would probably not have been calibrated for E10.

Dan

bigredbaja

My 03 496 Mag does the same but it seems to vary with the brand of fuel i burned BP most of lasy summer because it was the nearest station and then switched to Marathon and found better results. I still have soot but not as much, i did try ethanol free but the station is another 15 minutes donw the road and i didnt notice that much difference.

low_psi

I had a post a while back in regards to the Re-Flash of my 496 Mag (non-HO) PCM. I had my Authorized Merc. mechanic look my serial number up in the Merc. database and it did not sow any pending recalls. However, I personally called Mercury and gave them the serial number and they told my that my PCM would qualify for a free reflash to the current revision. However, Mercury would not deal directly with me. So what I then had to do was go back to my mechanic and have him send my PCM in to Mercury. The problem here was timing.... I did not want to lose a weekend on the water (Michigan boating season is short) and I couldn't get a guarantee from Mercury as to when it would be done. So I opted to overnight my PCM to Whipple and for a fee I had them put a Stage II flash on my PCM. Whipple was very fast and overnighted it back to me. Whipple also has a flash that was designed to just eliminate the excessive soot, but I figured if I was already paying for a flash (that was essentially free from Merc. why not have them put the stage II on it...). The soot did decrease a bit, however I did still have soot (but it was very greasy). But here is where it takes a turn away from the PCM. Apparently GM used too short of a bolt and bad intake gaskets that would allow oil to be pulled into the intake runners when under load n early 496 blocks.. So after a leak down and compression test, it was determined I had the bad intake gaskets.... So I ordered the updated gasket set and bolts from GM and replaced the intake gasket. Now after the intake gasket the soot I have is now very easily wipped off. However I still have the presence of a good amount of soot. I haven't really found on brand of fuel that works better than others. BUT, I believe I have a leaking injector. Upon start up I can see droplets of raw fuel in the water behind my boat, and occasioanlly can even smell the presence of raw fuel behind my boat (while at rest for a wile). Also within a few minutes all fuel line pressure is gone, after shutting engne off. Also when planing off at mid-throttle I get a small mis fire or sputter, however at 3/4 - full throttle it clear up. So my next stop is fuel injector service.

But I guess after my long winded post, my service and result from Whipple was great...

mittens

So merc can and will do this even on a older boat? I have a 2002 with 170 ish hours on a pair of 496 mags Would love to get them reef lashed with the less sooty tune.

Quinny

low_psi,
Any chance you still have the part numbers for the updated gasket set & bolts in case I need to go this route also? Thanks.

vindicator101

Had my 2001 done before last seasons by merc through a merc dealer and didn't cost me a thing. Mine was done to clear up some possible false voltage reading by the pcm but the bonus was it nearly eliminated all my soot problems too. All my cylinder now run pretty much even by looking at the plugs. Never had an issue with the flash.

low_psi

Let me see if I can find the old thread. I know I posted the part numbers in there. Raylar was helping me in that thread, I believe.

low_psi

I believe the part numbers are somewhere in this thread... http://www.offshoreonly.com/forums/g...-anyway-3.html

cigrocket

iTrader: (3)

Buddy of mine had his done from Dustin at Whipple, virtually no soot anylonger. Good investment, also better on fuel......at least he thinks...lol