Please move this if it is in the wrong place, I am new to this.

I recently purchased a 1993 civic with a D16Y8 and P28 ECU and vtec was working with no CEL. I noticed that the 2 pin pressure switch didn't have a connector so I got one and plugged it in and decided to do the wiring correctly as he had it going across the strut tower and I wanted to run it through the firewall.. I checked the ECU wiring and found that he had pins A4 and D6 connected and only going to the vtec solenoid. I redid the wiring and started it up and the CEL came on so I jumped the blue diagnostic connector and got code 21. I tried reverting back to the way he had it wired (he had it without pins in the ecu connectors, just wires and I kept the pins in.)and it still came up with the CEL after leaving the ECU unplugged for a few minutes. I have confirmed that the Solenoid is working(I heard it clicking when I applied 12v to it) but I still have the CEL after this. I am at a loss on what to do, but I am wondering if the pressure switch is faulty because he had it hooked up like that. Any help would be greatly appreciated, thanks!


This is how I wired the VTEC in, please correct me if this is wrong.


This is how he had it hooked up.'

Thank you very much for your time.

 

Update on some information:
When I was putting the motor in I did not connect the VTEC Solenoid and didn't pop a CEL
I have verified that the screen is not clogged and the oil is full and clean(it is a brand new motor)
The wiring is soldered securely and has good contact
I do not know where it redlines or if it activates VTEC because I am still breaking in my motor
I am starting to think it may be my ECU since it happened the first time I unplugged it? I don't know I am confused with this.

 

Update:
I figured out what was causing this issue. The pins on the ecu were not touching the pins on the harness, I bent the pins on the ecu down a slight bit so they would make contact and CEL went away!
If you are wiring VTEC in a swap make sure the pins are touching.

 

good job on diagnosing.