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Discussion Starter · #1 ·
I am puling the engine and replaceing it with another 5M that has been rebuilt. I have consulted a number of manuals and most say to remove the EFI Wire harness and pull it out from the cowl panel. Why is this necessary? I pulled the glove box but don't see a clear path to pull out the wiring harness through the mass of ventalation components.
 

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It's not. Unplug the harness and pull it through the firewall.
 
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Why is removing harness necessary? Can you just unplug it from all engine connections and zip-tie to side of engine-compartment to get it out of way?
 

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Discussion Starter · #4 ·
That's what I was thinking, unless there is something that catches on the transmission in the tunnel.
 

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Not sure that it is completely necessary to pull it out however I can say that it is a lot easier to make all of the connections to the engine while it is out on a stand compared to making the connections when it is in the engine bay. Pulling the harness out through the firewall is pretty easy.
 
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It's a lot easier to disconnect the harness plugs from the ecu and pull the harness out from the firewall and keep it with the engine while doing a swap than it is to disconnect and reconnect everything on the harness to the engine while it's still in the car. When it comes time to feed the harness back into the firewall to the glovebox area I use a flexible but stiff wire (coat hanger)and tape the plugs to it in a manner that each plug gets fed through one after the other and don't get bound up as they pass the heater stuff.
I am doing another 7mgte swap this weekend in my '84; I will take some pictures.
 

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Discussion Starter · #7 ·
My Engine was alread stripped down when I bought the car. So how much can be installed on the engine outside the car? All I had to disconnect was the starter & Oxygen Sensor so far.
17624
 

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You'll know what goes where when you pull the engine and swap the harness over. You may want to pull the ECU loose to unplug the harness' and better see where to push the connectors through the firewall. Be gentle---it's a very old , brittle harness. Take pics if it helps you remember what goes where.
 

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When the engine is fully dressed, it us had to get to the injectors plugs, and remove them aldo the dizzy & ignition plugs.
MUCH easier on a stand, this is why it is recommended to unplug at ECU and take it out with the engine.
 

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It's a lot easier to disconnect the harness plugs from the ecu and pull the harness out from the firewall and keep it with the engine while doing a swap than it is to disconnect and reconnect everything on the harness to the engine while it's still in the car. When it comes time to feed the harness back into the firewall to the glovebox area I use a flexible but stiff wire (coat hanger)and tape the plugs to it in a manner that each plug gets fed through one after the other and don't get bound up as they pass the heater stuff.
I am doing another 7mgte swap this weekend in my '84; I will take some pictures.
Exactly. Its not as hard as it looks just a little finicky. The 🔌s can be snaked through. Its a little harder putting them back. I always would tape up like the last foot or so of the whole harness very tight, as compact as I could get it, with a welding rod or similar affixed to be able to snake it back through. The problem with removing it from the engine is that all those wires and dozens of connectors on the hot side of the firewall are at this age, are brittle and pretty well "stuck". If you try to wrestle them off deep in the engine bay with so little access, you're likely to break them. By contrast, the three or so connectors under the dash are still in good shape and won't crumble to dust when you pull on them. Then once the engine is out in the open, you can "carefully" remove the connectors from the injectors and sensors to minimize damage.
 

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The plugs on the harness have corresponding parts or receptacles that only they fit in. Also the plugs tend to lie near where they go when you start to install the harness. I believe the two thermostat connections on the very front are colored.
 
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