Has anyone out there had there PCM reprogrammed on a stock 496HO motor? The soot on the back is just driving me crazy and just wondering if this helped at all. I've tried higher and lower octane gas with no relief. Was there any additional performance gains with the reprogramming? Thanks

The ECMs on my boat were replaced under warranty 2 years ago for this problem.
It's gone

I have seen Mercury reprogram the PCM for this problem and other minor calibration issues. Local dealer can't but they send it away to regional tech guy who has the software and code.

Thanks I Merc and do so checking.

They didn't reprogram mine, just sent me a new one. I have 5% of the soot I used to. By the way I was out of warranty when they did it. Thanks merc on this one.JC