502 to 540
 

I did a rebuilt 1996 - 502 and put a brand new 540 rotating assembly in . do i need to flash my computer? and if so who do i send it to ?

Send it to Mark at Precision Marine in Kenner LA.

www.pmefi.com

i would suggest not. the 502 fuel map is a bit fat anyway and unless you increased the compression ratio significantly, i think you will be ok. i have little faith in these generic one size fits all "reflash" deals. doing a comprehensive fuel and ignition remap on the dyno is one thing... anything other than that is just marketing.

While I agree with you, I think Smitty WAS suggesting he send the whole motor to Precision Marine. He did mine and I'll send him the next motor I build too.

The ecm does need to be reprogrammed, but unless someone has done that exact combo on the dyno before, there is no way to get it right on the money. It can be done in the boat, but you must have O2 bungs in the exhaust. If anything changes in the future, it will have to be tweaked again. The best bet is to do it on the dyno. Then you can put the engine in any situation possible and tune it for that. You can only do so much with the engine in the boat. You can hold it at a specific rpm on the dyno whereas in the boat it will accelerate past that point. With that being said, I can tune it either in the boat or on the dyno, whichever you would like.
Eddie

Sorry-- I need to be more specific. Like t500hps said, I meant to say send your complete motor to Mark, and when it comes back it will be broken in and ready to go. He just did my motors and they run AWESOME !!!

i would not wish to be misunderstood in this case. my first post was made , apparently, simultaneously with smitty's. mine reads as if i am suggesting that the ecu not get sent to that person that smitty talks about. that was not the case.

my answer was to the question " do i need to reflash " in the original post and my opinions and comments on reflashing were general in nature and not meant to imply anything negative about smitty's reccomendation.

i needed to be clearer.

If you choose not to reflash, at least install a wideband O2 gage in the boat. Install the sensor in the riser. Do a few searches on "Wideband O2", this has been covered before and will give you an idea what numbers you should see.

thankyou for all you suggestions.