How to wire in the MPI relay to use it for a standalone ECU (maxxecu)

[tiedchardshark]

Hello fellow techs,

Since i am switching to maxxecu I am wondering how to wire in the mpi relay so i can use it for the maxxec.

I am stuck at the mpi side.
pin 8 (mpi) goes to 63 and 66 of the ecu (switched to ground) if pin 3(mpi) gets power from the ignition sw.

Now, do I connect pin 8 of the MPI (63/66) to just the ground of the chassis?

Or is it better i switch over to some normal relays (bosch) if that is the answer how do i wire them?

With kind regards,

Tied

 

[steve]

I wouldn't hard wire pin 8 to ground unless you like dead batteries. The factory wiring feeds the relay with unswitched 12v (it's fused but constant). That helps take some of the load off the ignition switch.

If your plan is to use the ignition switch to activate the maxxec switching to a 5 pin Bosch style relay for the power side might be easiest since it doesn't share the power your switching with the relay coil unless you wire it that way. So you could keep the unswitched feed and route that to the normal output and then use the correct RUN/START output from the ignition switch to power the relay coil and ground the other side of it.

Depending on how your going to hook up the fuel pump to that ECU you might be able to use a relay for that too.

 

[19Eclipse90]

Not sure how relevant or helpful this might be or if you’ve already seen it:
1G Replacing 1G MPI Relay with Bosch-style Relays