Stay far far away from EFI. When it's good, it's great. When you have a problem, you're fucked.
This shit is too simple. FI is a closed loop system, it is so bulletproof as if it is a toaster, it is that closed in loop. You need no other components, meaning, to make toast. As if an engine is a closed loop system, you need no other theories:
Engine:
1. Fuel
2. Spark
3. Compression
FI:
1. Connectors not connected.
2. Wire out of connector.
3. Wire not grounded or internal short to ground.
This means, if I have no spark is the engine, it is like saying I have no ground is the electronics. If not connected, how simple is the loop? Every time you cry unit failed, somehow, it was a wire problem. Why then, did the new unit still act the same, i.e., no change. :roll:
This is where you lay down on a couch, discuss things with Dr. WATT is when you begin to pull your hair out... IS the deeper troubleshooting tree
But with 6 peenultimate basics that make absolute sense, there is no reason not to fear "The Loop(s)." It's a learning process like anything else you hammer out.