computers on 454 and 502 mpi
 

i just finished installing a 454 with 502 intake and harness. got everything worked out and boat is running great 70+mph(little scary though) in 18' 1978 glastron. my question is how do i found out exactly what computer i have, i think i am hitting a rev limiter around 4800-5000rpms, i know when i was building the motor someone said it could of been from an inboard. so i was thinking it might have a lower rev limit on it? where do i find the #'s that will identify my computer and what it does?
also whats the best oil to use in these motors? i wakeboard alot (2000-3000rpms)and when unloaded i like to run around 4500-4800rpms.
thanks for your guys help heres a video from last week running in the boat.(its still unfinished)
jay
http://www.youtube.com/watch?v=V-e56UmJ8j4

look on back of ecm,plus-do your plugs go in the opposite ends of the computer (mefi 1 or 2) or do they plug in the side of it,Smitty

i took pictures of everything,the top label may or may not be correct for this computer. any input about what im running would be great. i want to know what the rev limit is set at because i might have hit it and would want to know if it would cause any codes i need to have checked out hanks again. jay
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The plugs going in the ends tells us that it's a mefi-1 or 2,the 16234539 tells us it's a mefi-1 used exclusively by mercruiser,Smitty
http://216.230.203.183/acro/connect.pdf

It's a little hard to see with the flash of the camera on the sticker But I think I seen 7.4 [MEI] and you are right that is a inboard engine, also if you read the model part it tells you it is a inboard engine. No you will not set any codes hiting the rev limit with that ECM. And I believe your rev limit should be set to go off at more then likely right around 4850rpms. The 7.4 engines have all cast parts inside so they do not like to run them as fast, That is why you see 4400rpm max. Also that engine was hooked to a trany at one time that is why the max rpms are even lower then a stern drive 7.4L because that would have said 4200-4600 rpm. A good brand of 30w oil will work fine for that engine. Go to wal-mart for a better price on oil. Be safe in that boat I am not afraid of speed at all but that looks like I might rethink that idea. If you go test by your self you should ware your life vest and hook up the kill switch to your vest even if it is not for you then for some one eles on the lake also. Be safe:)

Please install a lanyard and wear it whenever you are on plane. Thats a big engine for an 18' boat.

absolutley will be the next thing i install before running hard again. i was crazy not having it hooked up before, the boat gets scary at 70+, still testing props for better handeling but i dont think its gonna help the chine walk alot. i did find a little play in the steering arm that i am going to tighten up though, so i hope that helps.
so what your saying is that i have the mefi 1 for and inboard and hitting the rev limiter with this ecu will not show any codes or affect any sensors? how do i know if the motor is 100% without running it on a scan tool, or is that the only way? will i hurt the engine with the timing getting retarded? im asking here because OSO guys know their sh--!
thanks for the help again...jay

Maybe adding some K-planes might help. Might look silly on an 18' boat, but will essentially make your hull longer (when trimmed level) and maybe more stable at speed.

well you do have a knock sensor and if the engine starts making some kind of knock noise then yes the ECM will back timing down and add fuel on it's owen to save it's self till you shut it down. And if the knock sensor dose set a code it will go away on it's owen after so manny key ups as long as it stops hearing it with in so manny key up's and going over a set numbered high rpms, I believe it needs to be over 4000 rpms to do a self test then the code will erase it self. But in till that happens the engine will still run up to top rpms untill the knock sensor hears the sound again then it will reback it self down some. As long as your timing is set to specks and every thing is working right then you should be ok and not hurting the engine, Also run 87 fuel only it will work better all around.

ok sounds all good,im going to try some tabs soon also so ill get back with some results. im set at 8 degrees can i go to 10?
and if now i could only stop the overflow from pouring out on the cooling system, still trying to figure out whats wrong.
thanks for the info...jay