Issues with a 2003 225 EFI power head that replaced a 2001 225 Optimax.

[Cccoachd]

14 years ago my 2001 225 Mercury Optimax blew up. I replaced the power head with a 2003 225 EFI power head. Lately (last 7 years or so) I have been having issues with rough idling to the point of shutting down, and losing up to 2 cylanders when trying to get on plane. My mechanic noticed that the computer unit on the motor still "thinks" that the motor is a 2001 225 Optimax. He believes this is causing the issues I'm having. My question is this: will changing the computer unit on the motor solve my issues? The mechanic says possibly but possibly not. I'd rather not spend $2000 on a new computer unit if it won't solve the problem.

 

[Chris1956]

Can the software be changed to match the new power head?

 

[Cccoachd]

I'm not sure being it's such an old model but I was led to believe the whole computer unit would need to be replaced. And even then not sure if it would solve issues

 

[Chris1956]

That begs the question....is the computer wiring the same between EFI and Optimax? In not, it may never work right. If the wiring is the same, update of the sw should be able to fix it, one would think.

Although I do not know it to be a fact, manufacturers usually allow for SW updates, as they are likely to be needed occasionally.

 

[Cccoachd]

I was told they are not the same. And gauging from the constant issues I've had I'm guessing that is the problemZBut even changing out the computer is iffy from what I understand

 

[Faztbullet]

Did you swap whole powerhead or just block and swapped parts?

 

[Cccoachd]

Did you swap whole powerhead or just block and swapped parts?

I thought it was the whole powerhead but now that I know the ECU doesn't recognize the new motor I'm beginning to wonder.

 

[Dukedog]

ya jus can't use opti-pop 'lectrics ona plain 'ole efi motor.. will never be right.......... jmo.

 

[Cccoachd]

Question is will a "new" ECU t match the EFI solve the problem...?

 

[Dukedog]

don't know sittin' here ona computer??? don't know about tha of tha rest of tha parts??? who told you you could use any of tha opti parts on tha normal efi ta start with? thats who i'd be askin'................. jmo.

 

[Cccoachd]

Nobody told me. It's just what happened when the power heads were switched out (or so it seems). My mechanic noticed the ECU recognized the old motor NOT the new one. So for sure that wasn't swapped out.

 

[Dukedog]

what your sayin mighta happened.. its something i've never even thought of so i wouldn't be able ta say yes or no.... but seriously doubt anything opti would work on anything normal efi..... jmo.

i'm surprised that any of tha receptacles were enough of a match ta plug it in???

 

[Cccoachd]

I agree. I have had issues since the swap 14 years ago. Sometimes the motor ran fine others times it didn't. Never had to be towed in but sometimes when on plane it would just shut down. It would start up again but might happen 3-4 times before running down the lake. Very frustrating. Was told it was a VST issue. The more I read about the "establishment" that did the re power the more I think I didn't get what I paid for...unfortunately!

 

[Dukedog]

interesting... don't know of and have never heard of anything like this before... hope for tha best for ya!