The key to a successful EFI upgrade starts with making reliable wiring connections with the proper tools, techniques, and crimp terminals. Holley's EFI program engineer Doug Flynn, shares his tips on the basics of making proper wire connections. 

1) Never Simply Twist Two Wires Together 
Many people make their EFI wiring connections by splicing two wires, twisiting the ends together, and wrapping some electric tape. This only works until something tugs on it and the connection is broken. 

2) Use Proper Insulating Crimp Terminals
Crimp terminals provide a positive connection. Use the appropriate terminal for the gauge wire you're using. The color of the crimp terminals indicate the gauge of wire they are made for; Yellow = 12-10 gauge, Blue = 16-14 gauge, and Red = 22-18 gauge wire. 

3) Use A Crimp Tool: 
There are many crimp tools available that are inexpensive. Most will have the gauge color indicators to know which part of the tool to insert the terminal and wire to make the crimp. 

4) Never use T-Tab or Scotch Locks:
These type of connectors do not guarantee a good connection and can fail at any time.

5) Use Splice Connectors And Solder Wires Together:
The best way to connect two wires is to use a splice connector and solder them. This provides the best and most reliable connection. Follow up by covering the connection with heat shrink. 

6) Non Insulated Crimp Terminals Are Installed Differently:
Non insulated connectors are commonly used for wires like the main power and ground wires for EFI systems. These types of connectors should be crimped from the back side, or the side without the seam or split in the connector. Many crimp tools indicate which bump on the tool is used for non insulated terminals. Once it's crimped, it's best to solder the connection and cover with a shrink wrap. 

Most of the trouble-shooting Flynn says he's done on EFI installations are a direct result from poor or loose wiring connections. By making the proper connections during the installation of your EFI system will ensure that it will work properly and without any problems in the future.