A very long story in brief.
The car came in with a broken timing chain. The head was removed, various valves replaced etc and all reassembled with no other issues. The engine intially ran but had two chuffing injectors. These were removed, new seals fitted and all reassembled. The problem is that it has never run since.
No fault codes stored and live data all looks good, including fuel pressure which reaches 300 bar when cranking.
I'm not familier with this delphi system but I have found that it uses conventional coil injectors. The resistance of these has been checked back to the ECU with all four reading 0.7 ohms with no short to earth.
I have scoped the injectors but have noted a rather unusual injector pattern. The current draw seems about right but the voltage looks very odd.
I did initally think this must be wrong but I'm not so sure now as I did only check one wire of one injector and it looks like the positive side. I'm confused as to why it apparently only shows current being drawn on one pulse event. I guess it might be supplying 12 volts to all four injectors as the same time but this trace is obviously only showing current draw from the one injector being tested.
Another look at slightly more detail. I've either got something very wrong with the ECU or these injectors as switched at the same voltage as conventional petrol injectors which I have never seen before on a common rail injector.
Lastly, if I carry out an injector actuator test on all four injectors, the engine will fire very briefly on completion of the test. Again, I can only assume that it injects a small amount of fuel into the bores on test which then allows it to fire on the next cranking.
Every days a school day! Just wish I could figure out why it won't start!