1999 Dual 454 with Mefi 3 ECM - Master/Slave relationship
Posted: December 13th, 2023, 5:20 pm
Hello all, in my checking of actual engine hours using my Rinda software vs the Helm Hour analog gauges that are not 100% accurate. I noticed that both engines come up as "Master" and NOT as ("Master"/"Slave") on the bottom left of the screen when communicating with the engine. Is this an issue or a non-issue? Any guidance would be greatly appreciated.
Information of Vessel:
1999 Carver 406
Engine Starboard Mercruiser 7.4L MPI MIE V-8 gasoline naturally aspirated engine - 330hp SN- 0L303931
Engine Port Mercruiser 7.4L MPI MIE V-8 gasoline naturally aspirated engine - 330hp SN- 0L303934
MEFI 3 ECM on each Engine
I found this text in a publication named
"MerCruiser EFI Engine History and Major Changes"
"The engine control module (ECM) on all 1996 and newer model year EFI engines has the
“Power Reduction Mode” disabled. Because of this change, it is important that 1995 (and
older) models not be intermixed with 1996 (and newer) models on multiple engine boats. It
is important that all of the engines in a boat have either the power reduction mode enabled
or disabled, but not a combination of both.
The 3-pin Master/Slave connector and the 2-pin Safety Lanyard Stop Circuit connector have
been removed on some 1996 and newer MEFI 1 models and all MEFI 2 and MEFI 3 models.
On these newer models, if the Master/Slave functions are desired, it is necessary to build a
custom data link harness and connect it between the DLC connectors on the engines. The
serial data terminal (Pin G, orange [or orange/black] lead) on the data link connector
(DLC) of both engines must be connected together and the master/slave terminal (Pin
H, yellow lead) on the Slave engine’s DLC must be grounded."
I read this as Master / Master is OK
Information of Vessel:
1999 Carver 406
Engine Starboard Mercruiser 7.4L MPI MIE V-8 gasoline naturally aspirated engine - 330hp SN- 0L303931
Engine Port Mercruiser 7.4L MPI MIE V-8 gasoline naturally aspirated engine - 330hp SN- 0L303934
MEFI 3 ECM on each Engine
I found this text in a publication named
"MerCruiser EFI Engine History and Major Changes"
"The engine control module (ECM) on all 1996 and newer model year EFI engines has the
“Power Reduction Mode” disabled. Because of this change, it is important that 1995 (and
older) models not be intermixed with 1996 (and newer) models on multiple engine boats. It
is important that all of the engines in a boat have either the power reduction mode enabled
or disabled, but not a combination of both.
The 3-pin Master/Slave connector and the 2-pin Safety Lanyard Stop Circuit connector have
been removed on some 1996 and newer MEFI 1 models and all MEFI 2 and MEFI 3 models.
On these newer models, if the Master/Slave functions are desired, it is necessary to build a
custom data link harness and connect it between the DLC connectors on the engines. The
serial data terminal (Pin G, orange [or orange/black] lead) on the data link connector
(DLC) of both engines must be connected together and the master/slave terminal (Pin
H, yellow lead) on the Slave engine’s DLC must be grounded."
I read this as Master / Master is OK