496 mag ho carbon build up
10-07-2011, 08:09 PM
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Location: Brownstown, Michigan
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496 mag ho carbon build up
My baja 38 special has twin 496 mag ho's. They have 120 each and are stock. My exhaust tips pretrude my hull 1" and have the rubber flappers on them. I get so much "soot" build up on my transom that it is annoying. My question is, do I remove the tips and put longer angled tips on to get the exhaust closer to water. Or do it take my computers out and have them rebooted so the engines do not run as rich as the factory sets them to. Please help. Thanks
10-07-2011, 08:19 PM
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Have the ECM's reflashed and run 87 only and your soot problems will go away.
10-07-2011, 11:28 PM
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Have a certified Merc Mechanic call Mercury with your engine serial numbers. If you have earlier 496's they may not have received the correct PCM updates. Mercury will reflash them free of charge, but you have to have a Merc. Mechanic handle it. I see you are in Brownstown, go see Dwayne at Boaters Value in Wyandotte. Tell him Brad with the White Velocity sent you in. He will help you out.
I was in the same "boat" pun intended...... My Velocity was covered in soot. As it turns out mine needed the PCM re-flash. Merc said they would flash for free, but in the middle of summer I wanted it doen ASAP so I paid WHipple to do a Stage II flash, which adjusts the fuel curve, and adjusts the timing curve to optimize Premium Fuels. I now have to run 91+ Octane, but it did wake my 496 up. I don't know with a 38 special, the extra few HP gained by the WHipple Re-Flash would be worth the $$. If your PCMs require a reflash, I would have Merc take care of it. It's the end of the season, so you have plenty of time...
I was in the same "boat" pun intended...... My Velocity was covered in soot. As it turns out mine needed the PCM re-flash. Merc said they would flash for free, but in the middle of summer I wanted it doen ASAP so I paid WHipple to do a Stage II flash, which adjusts the fuel curve, and adjusts the timing curve to optimize Premium Fuels. I now have to run 91+ Octane, but it did wake my 496 up. I don't know with a 38 special, the extra few HP gained by the WHipple Re-Flash would be worth the $$. If your PCMs require a reflash, I would have Merc take care of it. It's the end of the season, so you have plenty of time...
10-08-2011, 07:35 AM
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Thanks for the quick reply. Low Psi, I think we have a mutual friend named " Gary" in common. He told me what you did but I did not know I could have them reflashed by Merc for free. I will talk to Duane down at BV and see if he can help me out. Thanks
10-08-2011, 04:02 PM
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Yup I know Gary. Merc will reflash IF yours show up in their system as having been missed when the software update came out to resolve the "Rich" condition. If not Whipple does have a stage 1 flash that is much more reasonable in cost. The stage 2 is upwards of $700 - $900 (I cna't remember) and new 120 degree T-Stats. And I don't think you would really see much benifit in a 38 special.
