S40 T4 98y No idle; EFI-254

[Endorphin]

Hello guys.
Pretty new here.
I have the following issue with my t4 (it would be a bit informational one )

So the car is S40 t4 98y with a lot of things repaired in 3 months up to now.

When starting the engine for 1st time after finalizing the fuel system, I noticed there is hiss-ing sound from one of the Quick connections to the Fuel rail lines. In a bit of a positioning it better it spilled a bit of petrol and it stopped hiss-ing. The petrol spilled right on the cable branch for the Coil cables and on one of the Engine ventilation hoses i suppose.
To check whether i fixed it, I powered up only the fuel pump with additional cables, and the Car battery wasn't connected then. The Fuel pump cables however were. (external fuel pump)

When fixing the hiss-ing connection, at attempting to start the engine once again it had no Idle.

So not it shows EFI-256, after driving a bit is showed also front and rear O2, but i think i know why.
About EFI-256, i checked the engine relay and it is working fine (although i don't know exactly why it is for).
I replaced the Idle Control Valve (first cleaned mine, it didn't changed the situ) and with the replaced valve, when i Delete the Error code it revs a bit (to 3000rpm) and the light comes on on the dashboard and it drops again.
It actually has an Idle which is arround 500rpm, the vac at this Idle is still -0,7bar (on boost meter). When I remove one of the vaccum hoses, it goes up in rpm to arround normal ones. So it needs more air i guess.

When driving, from time to time without changing the position of the throttle pedal, it runs like i did pressed it, and then again goes to normal. So it engages the Idle Control Valve i guess, because when it happens, the vaccum in the Inlet Manifold also drops, so - it has no other possibility to get the air insite the manifold.

Not too short, but ...
Diagnostics and Error codes readouts made with Delphi.
I have also VolFCR, but I dodn't had the exact computer then.

So it had previous problems with Coils cables.
Can it harm smth when externally powered up the Fuel pump, and can the fuel make some problem on the cables - what to look for?

I found one thread rather actual, but it doesn't have a conclusion
https://www.volvoforums.org.uk/showthread.php?t=287353

Excluding the poor Idle and the error code, the car runs fine.

[Endorphin]

It is EFI-254, not 256. My bad.

[Endorphin]

Somebody atleast to tell how this Error code is generated?
EFI-222 is short circut in the circut to the system relay, close enough.

[RickHaleParker]

Both of them codes are the System relay or the wiring to the System relay.
There are two versions of both codes, Too high and Too Low (Shorts and Opens.)

1. Check and clean the System relay socket.
2. Get a spare relay and try swapping the relay.
3. Check the wiring to the System relay for shorts and opens.

#21 is the System relay.

[Endorphin]

Both of them codes are the System relay or the wiring to the System relay.
There are two versions of both codes, Too high and Too Low (Shorts and Opens.)

1. Check and clean the System relay socket.
2. Get a spare relay and try swapping the relay.
3. Check the wiring to the System relay for shorts and opens.

#21 is the System relay.

2019-11-25 (6).png

Thank you for the reply, RickHaleParker.
I swapped the relay with #20 from the picture (fan relay I think, it is the same as the system one) and no changes there.
The circuits are fine, they are not opened, but for shorts - I did checked, but not all of the cables and connections. They are a lot, and it can have short with each of them in the sheaf of cables.

I had diagnostics once more, so I made a separate tests of all components there(w/o engine working, only Ignition ON). The relay functions when I engaged for example the fuel pump. The ICV does worked verry shortly in time compared to fuel pump and also it made a lot of short but strong pulsations. Most of the times the computer cached the error when performing longer tests (fuel pump etc. which engaged the System Relay).
The only thing which does not work is the ICV. (Works but is not enough opened). It showed 11 or 10,7V on the ECU pin - barely opened.

Another clue is what happens when I delete the Error. Most of the time the engine dyes out, because the ICV closes totally(12v on the pin), but in some other cases the computer opened the ICV a lot, so it revs strongly to 3k rpm, and then caches the error and againg to almost no air.
Can it have some ECU problem because of the 12V supplied directly and only to pin66? (w/o pin 29 and 30 to have 12v)
It happened after I electryfied the FuelPumt w/o removing the fuse, thus send 12V to almost each sensor + ECU pin 66..