Baffled by ABZ

[SimonT25]

Dear all,

I am new to this forum and therefore would like to say hello to you all

Can anyone impart some knowledge on to a problem I am currently stuck with?

Some years ago I took the challenge to drop an Audi ABZ engine (4.2ltr 32V 1997 motronic controlled ECU) into a friends T3.

My friend (Andy) found a bench running ABZ with fuel connected via in line pump and 12 v to starter. By all accounts this engine run with no issues with the immo box and OBD II reader all in circuit.

Cutting a very long story very short I have know come to put this engine in and have tried to start it in the same manner as before and I cant get the engine to run for any more than 4 secs.

I have had the Immo removed from the Motronic ECU and have the same symptoms.

I have 3.5 bar of fuel pressure, clean spark on all cylinders on cranking, injection pulse on cranking proven with a Noid light but alias no continuous running.

Can anybody out there please help as i have no pretty much exhausted all my knowledge on this.

What follows is a list of all of the checks I have made:-

Fuel pressure 3.5 bar (regulated on fuel rail at 4 bar)
Spark tested on each cylinder
Injection pulse on each cylinder tested by Noid light (after a few seconds running noid light goes dim and engine stalls)
All injectors tested from the ECU connection by grounding cable to earth whilst 12V applied and injectors all operate/click when grounded
Whole engine loom pulled apart checked for any wires grounded
Whole loom checked end to end for continuity and then to 0volts
Engine speed sensor replaced for known good sensor
Cam position hall sender replaced
Lambda sensors replaced
All fuses to final output stages, injection supply checked, cleaned and replaced
Motronic current supply relay checked
5v found at knock sensor and hall sender
Throttle position potentiometer checked
Injectors removed and tested for injection on cranking
Throttle body checked for functionality
Idle stabilisation unit removed cleaned at contact to throttle body and replaced
MAF to throttle body rubber hoses checked for splits holes etc
3 x Motronic ecus are currently being tested at AUTOMATEC, Ivybridge, Devon. Just waiting outcome of that
Things that I am not to sure about are the following

The air manifold change over Vv (changes the angle of air flow as engine speed increases to allow more air into cylinders?) has a pipe which is not connected but when engine fires a vacuum is pulled within the pipe. As it is a vacuum I have just blanked the end of the pipe. the pipe runs away from the unit towards the drive end of the engine. all connections on the unit are fitted tightly
I haven't connected the charge light of the alternator so there is no increase in voltage once engine starts does this light need to go via an LED before being connected to earth?
VagCOM faults show idle stabilisation valve signal implausable have been told that this should not stop engine from running.

If anybody out there has had a similar problem and managed to sort it could you please spend 10 mins to help me out. If you have got this far then you have obviously got a little bit of time on your hands.

I know I sound a little desperate but I really can not think of where to go next.

Many thanks for those of you that have got this far. Realise that it is a bit of an epic.

look forward to any replies and any suggestion regardless of how trivial you may think it is.

Regards,

Simon