The 5th injector always comes in on a cold start, for information its controled by the "Thermo timer" [ Brown plug ] under manifold....as soon as engine warms up Timer cuts voltage to 5th...these cars need the 5th on start up Cold, as on cranking Cold engine all 4 injectors wont release Fuel, you confirm you let the engine warm up before driving off....should not be needed...but its a sure sign the "Pressure actuator" is not getting a voltage signal...or is faulty...the reading at the actuator itself [ plug off ] is 16 to 21 ohms...do check also on the Black ECU pin 1 [ colour Black/green ] is live when Ignition on, this Black ECU has its own fuse, for infomation the 5th injector is independent wired and nothing to do with ECU, the Black ECU sends the Voltage [ varies on how cold ] to the actuator, which works on the "Bi-metal princeible"...ie resets itself on cooling down. If no power at pin 1 these cars will start eventualy after much cranking....but keep in mind the 5th injector will be shut down after approx 5/6 sessions of cranking, this is the safety side coming in by the "Thermo timer "...then of course it never starts...after 15 mins or so Timer resets...the 5th injector is then back.. Peter