Like puzzles? Then help me identify this mystery connector...
 

I was poking around my ECU and to my horror I saw that several of the wires going into the harnesses had been spliced into. Evidence of the previous owner's poor electronics skill was everywhere: wires just stripped and twisted together, sticky tape dangling and not covering anything, bare wires, etc.

I noticed that four of these splices lead to an unused four-wire connector, so I decided to trace the function of these wires. They are as follows:

1B - Data Link Conn
4S - CRV Solenoid
4S - (CRV again, this one comes from the ECU itself)
4D - EGR SW

The following wires didn't lead to the connector, but had been spliced into, appearing that they had been used at some point:

2B - Data Link Conn, Instr Cluster
3G - Throttle Sensor
1O - Pressure Sensor
1A - Room Fuse
4C - Ground
4W - Fuel Injector (? I may have gotten the color on this one wrong)

One more thing, there is a wire leading into the driver's floorboard that is spliced into the O2 sensor wire (in the engine bay).

So what do you think all this is? Remnants of some kind of electronic monitoring/control device, like an Apexi piggyback? I'm getting error code 46 - CRV Solenoid open or short circuit, so now I get to undo all of this just to get it back to normal. It'll be worth it if it fixes my boost problem!

I appreciate any insight.