Hello I will help you with your question,
Has someone connected the D-Check connectors under the dash near the steering column?
The black and the green connectors should be hanging free and not connected.
Let em know so I can help you
Is the green connector disconnected as well?
i unplugged the green connector and engine light quit flashing
Did the other components stop cycling?
OK, that took it out of D-Check mode, leave the connectors disconnected. You need to confirm cam timing and see that the signals from the cam and crank sensors are strong and clean.
Let me know how I can help you
You should see a clean signal of at least 1 1/2 volts at idle on the oscilloscope for both the cam and crank sensors.
If you have a P0204 that is an injector code, is the injector plugged in? Have you swapped the injector position to see if it moves with the injector or measured the resistance of the injectors so you can compare the ones that are not setting codes with the one that is?
This is an electrical code not a lack of fuel.
How do you know that 2 and 4 are not firing?
If you unplugged the injector while running that could be why you have a P0204!
So it IS firing on 2 and 4 but you don't think you have fuel?
All I can tell you is that when you have one bank not firing it usually is that the cam timing is off by a tooth or more.
How did you check the cam timing and what marks did you use?
The double marks align with the double marks on the lower cam gear and the single marks align with the single marks on the timing cover while the balancer is on the T mark?
If this is the case the cams are in time and I have no further help to offer. You have a troubleshooting problem that you need to verify signal from cam and crank to the computer, from the computer the firing signal to the coil and from the coil to the plugs, against the cam and crank signals display the injector signals and be sure you have compression.
With all the above factors in place the engine will run on all cylinders, find what is missing and you know why it is missing. Have you checked compression?
Yes I would start with the cam and crank signals then swap the injectors and see if you still get the fuel fouling on #1 or see if it moves to #2.
You either have a fueling issue from the sensors or the injector is clogged/leaking.
Its time to play swaptronics or you need an ignition scope with a pinpoint scope to see the signals together to be sure they are present and in time with each other.
Let me know how I can help
That is why I asked about compression, if the valves are hanging open it will show as low compression. You may need to clean or replace the plugs if they are fouled.
The lash adjusters on this engine (2.5 DOHC) are hydraulic so they should maintain adjustment but I do see receding valve seats (you had a valve job=should not be an issue) but there could be carbon holding the valve open. Again it should show in the compression.
Let me know what further questions you have