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MEFI 3 or 4???

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Old 12-10-2005, 06:49 AM
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Question MEFI 3 or 4???

Looking at a Mercury part # 861721T2 ecu, with a label ECB4 from a 1999 454mag, is this a Mefi 4?

I've done some searching here on OSO and I see that the recommendation is to go with a Mefi 4.
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Old 12-10-2005, 07:15 AM
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Default Re: MEFI 3 or 4???

It is a mefi 3. I think I know someone that has one available if you are looking for one.
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Old 12-10-2005, 08:57 AM
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Default Re: MEFI 3 or 4???

Are you looking to upgrade or just replace? The ECB4 is the programing code.
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Old 12-10-2005, 09:44 AM
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Default Re: MEFI 3 or 4???

I've got 94 carb 454's right now and looking at complete mpi setup someone took off a 99 454 mag. Again, I think everyone says to go with the mefi 4, so want to be sure I know what I would be buying.
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Old 12-10-2005, 10:04 AM
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Default Re: MEFI 3 or 4???

Mercruiser never used MEFI 4. They went from MEFI 3 to ECM/PCM555.

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Old 12-10-2005, 02:55 PM
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Default Re: MEFI 3 or 4???

The MEFI 1 has the connections on the small sides of the computer, 180 degrees apart. The MEFI 3 has both plugs facing the same direction on the same wide surface. I am not aware of them using the 2. The 4 as stated above was never used. There is a plug that Merc has came up with to connect to a MEFI4. I hear Merc has no more 3's and are selling 4's as replacements.
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Old 12-10-2005, 03:45 PM
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Default Re: MEFI 3 or 4???

Looks like it's a mefi 3. Thanks for the descriptions!

Intake Manifold; Intake Plenum ;Injectors ,Throttle Body Assembly, ecu, wiring harness and I'll need an electric fuel pump. What else do I need?

Sending units of any kind?
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Old 12-10-2005, 06:01 PM
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Default Re: MEFI 3 or 4???

Originally Posted by East Coast B
Looks like it's a mefi 3. Thanks for the descriptions!

Intake Manifold; Intake Plenum ;Injectors ,Throttle Body Assembly, ecu, wiring harness and I'll need an electric fuel pump. What else do I need?

Sending units of any kind?
You will need a coolant sensor, Knock sensor, and the intake air temp sensor. We have a bunch of take off parts around if you need them.
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Old 12-11-2005, 06:08 AM
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Default Re: MEFI 3 or 4???

Is there any difference in the main plug on the wiring harness for the 99 compared to my 94 setup??? Or will it plug right in??
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