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ECM Reprogram

2K views 21 replies 9 participants last post by  Strip Poker 388 
#1 ·
The previous owner sent the ECM out to get recalc'd, over the winter, boat wouldnt start this spring. We swapped it out with a friends ECM and it fired right up.

Sent the ECM back to shop that did the program, havent heard anything yet. What could have happened? This is a very reputable engine builder.
 
#4 ·
I don't think the merc computer does much with the timing, but I could be wrong. I was under the impression that the timing curve was set with the thunderbolt ing. in the HEI module. Hopefully the comoputer is still good and they can just reprogram it. Sometimes when flashing the computers if some of the parameters are way out of wack, or there is some type of power failure with the equipment, it can lock up the ecu.
 
#6 ·
Yes you can adjust the timing with the computer... I just did it... and you can adjust it manually on the Distributor... I am not expert either, It was DONE FOR me.. not myself... but I was there taking notes :bandit:
 
#8 ·
Hopefully it wont take a couple tries, He said he would reload the program and maybe it did'nt take the first time. I am hopeful that they will send it out today, next day air.

It's going to be 80 degree's this weekend I've got the itch bad, I'm sick of washing a boat that I've never taken out!
 
#9 ·
Hopefully it wont take a couple tries, He said he would reload the program and maybe it did'nt take the first time. I am hopeful that they will send it out today, next day air.

It's going to be 80 degree's this weekend I've got the itch bad, I'm sick of washing a boat that I've never taken out!
 
#10 ·
Here is the latest, sent the ECM back to get reprogrammed, put it back in and it still wont start,

Just to refresh, this is a 2000 502 MPI (252 hrs) that ran perfectly last fall, over the winter ECM went to (yet un-named, very well known) engine builder for a recalibration. fired up this spring and it wont start.

It starts right up, runs for a second and dies, builder said he loaded a completely different prgram this time and the ECM must be bad.

How can that happen? Ran great before it went to him.

Waht are the options? It is a MEFI3, they are $1500 at BAM for a upgrade kit to a MEFI4.
 
#15 ·
I fried mine last yr, '99 502. screwing around with the warning buzzer system. Found several 4 sale going for an averaging $350-$400. You will need one with the same program code as your current one. That's what the sticker is on them, the code. If not, then will have to be reflashed to your code.
 
#20 ·
Problem seems to be identified, for a while Merc made MEFI3's that had exclusive software, the standard program to recal, doesnt work. The new ECM I sent up was a different model # with the standard program that can be recalibrated.

Should be good to go, I will get it back and test it on Thursday.

My old ECM is OK and will be able to get reprogrammed with different software. I'll have a spare one to keep or sell.
 
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