Engine's are '96 MerCruiser 7.4 LX Mpi's. I'm having erratic idling issues as discussed in this thread Help Chasing Erratic Idle Please

I ATTEMPTED to swap the ECU's today and happened upon MEFI 1's with two different Model numbers, #16234539 and #16189069. See attached picture, they are different sizes. I stopped right there as I'm not sure whether or not they are swap-able. The #162 was used by Mercruiser the #161 was not and seems to be a GM car/truck ECU (see attached picture from MEFI Burn). So now I have more questions than answers.

Should the Non-Mercruiser unit (#161) even be on a boat? Did modifications to sensors, harness, tune etc. need to be made to use in on my marine engine? I was afraid of swapping them and potentially cause more harm than good.


https://uniim1.shutterfly.com/ng/ser...714842/enhance

https://uniim1.shutterfly.com/ng/ser...714862/enhance

Thanks for any insight you can lend.
Keith

The 16189069 WAS used by Merc. That is the OEM unit on my 95 Merc motor. Still using it today. You should be able to swap them.

I would check the sensor plugs between engines and compare them to see if they are the same and then put in the correct unit.

10-4 exactly the same. As far as I can see the engine harness' are identical.

Keith

But is the tune the same? Fuel-ignition curves.

Considering MEFI stands for Marine Electronic Fuel Injection, I doubt it came off a car.

To answer the above and for the archives, I called MEFI Burn today with the issue. They stated any of the model numbers listed in the picture in post #1 will work but as Derek eluded to they must have the correct tune installed. MB also stated the MEFI's were used in other platforms other than the marine industry. If I have purchase another unit I'll need to ensure its loaded with the proper mapping for my engine, no matter what the model number.

Atleast I now know I can swap side to side and see if my issue goes away.

Keith

The GM ramjet motors and others used the MEFI controller.

The tunes between the motors should be identical assuming they haven't been fiddled with. If it comes down to installing a replacement ECU just copy one file and transfer it to the the new unit.

I understand that, but its not used in any production automobiles. .