Jynx

Hello all, I think i have an ignition advance/retard issue with my Mag 496 ho which is standard with no mods whatsoever, and only 160 hours of use. I purchased a Rhinda Diacom unit hoping to find relevant fault codes but have found none. Have noticed strange looking variations in the ignition timing at varying rpm`s, but am no expert. I was wondering if there`s anyone with the same Rhinda unit that would be interested in taking a look at the saved file I have from the Rhinda unit, preferably someone with a file from a fault free engine for comparison.
Any help would be greatly appreciated though. Regards Jeremy

Raylar

If you are scanning a stock 496HO engine at idle, Merc has some pretty crazy low rpm timing in the engine that can move from actual negative numbers lets say -11 degress and back to +12 degrees just with a little variation in rpms and especially when you shift in and out of gear. Merc did this to help protect the Bravo drive when shifting. If you are not having a large idle rpm fluctuation and the engine accelerates and runs fine underway, just don't worry about that timing. Old chinese proverb say- "If it ain't Broke- Don't Fix It!!"

Best Regards,
Ray @ Raylar

Jynx

Hello Ray,
Thanks for your reply. Yes your description fits exactly for the idle readings. I do have issues with the performance of the engine though and it`s not only at idle unfortunately. It started as an intermittent problem which now seems to have become constant. I was hoping to have someone who also has the same Rhinda Diacom diagnostic software installed on their PC take a look at the files I have and see if anything stands out as unusual to them.

Raylar

Jynx:

Please describe the problem with power and running you are having with the engine at speed under loads. If your alarm is not sounding (guardian Mode) at all underway at power your Rinda may not show the problem as a scan code. You may be having something simple like spark plug problems or a fuel system issue. Let us know whats going on an d maybe we can assist.

Best Regards,
Ray @ Raylar

Jynx

G`Day again Ray, Thanks again for your reply and also your concern. I was 100% sure the problem I had was an electrical issue because of the way it has been an intermittent misfire fault developing for about 6 months, but also an intermittent fault that has gradually been getting worse each time it occurs and also becoming more and more frequent to the point where now it`s no longer intermittent at all. Which is the reason I was hoping someone could take a look at my Rhinda file to see if there were any anomalies that they could spot. Anyway to cut a long story short, because I didn`t find anyone here to take a look and because it`s near the end of our summer boating here in Perth in Australia, and we just simply don`t want to miss out on any more weekends on the water, i`ve bitten the bullet and taken the boat into a local Mercruiser dealer for them to take a look at. But Sincerely, thankyou for your interest anyway Ray.
Regards Jeremy