Hehee - we have it now for future reference.
The "gronk"... when a gas engine's ignition timing is too far advanced, the fuel will light off so early in the upstroke to TDC that it stops the piston slightly before going past TDC, and will stop the starter in it's tracks. If it's bad enough, one can easily wear out a starter in no time. It sorta goes; "Gronk, tink, gronk, tink, and then when it fires off, varoom!" - LOL - gotta love explaining sounds via writing! You'll hear the starter turn the engine, then a sudden, albeit slight and non-damaging "tink" that is very similar to pre-ignition ping, and the engine will stop turning until the expanding gas from the detonation succumbs to the force of the starter again. Some of us older people probably have experienced similar issues to this first hand (or leg) trying to kick-start a motorcycle... not too fun when it kicks back on you. I've had lawnmowers do this too and near about break my wrist yanking the pull start out of my hand. It typically only exhibits this behavior more when the engine is warm.
I tried to find some examples of this online, but failed. I may have to do a short video next time I take the boat out as an example.
I'm not entirely sure if the ECM in our boats utilize a knock sensor. I'd like to get my hands on some info for the ECMs in these engines and play with it. When I started tuning the Corvette I had, nobody had any ECM definitions for that model ECM. The locations, parameters, and information for much of the calibration ROM was unknown. I took a "dead" ECM, extracted the program ROM from it, ran it though a disassembler, then from that was able to reverse-engineer the ECM program enough to get the information to discover where all the important calibration data tables were mapped in the calibration ROM. It is not a fun process, but it was needed since there was no publicly available information on that particular ECM. I would do this on the Mercruiser 555 ECM that's in most of the Mercruiser EFI/MPI engines out there. It would make it easy to change fuel schedules, etc. for modifying our engines with bigger power adders. It would be easier if they had a removable UVEPROM, but I think they are electronically erased and programmed via the diagnostic port. That rules out me being able to remove the cal ROM and copy it with my EPROM burner. Grr.
Sorry - thinking out loud here I guess
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