Baffled by ABZ
 

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

Welcome.. +++

I'm no expert either, but I'll give my thoughts,

The immobiliser is classic for cutting out the ABZ after around 2 / 3 seconds after starting. 4 sounds a touch long, but maybe your clock is fast lol

The ABZ is pretty bullet proof. At idle with no load, its quite resilient to hoses being disconnected and generally all over the place.

If it fires up quickly, first time every time, I'd rule out fuel, spark plugs and coil packs - In fact, I'd look back at the immobilsier again.

Mechanically speaking, unless its a duff head gasket or overheating, once the ABZ lump fires up under its own steam, it usually keeps going, albeit roughly in some cases, until someone, or an immobiliser stops it.... +++

IT,

Many apologies to you all for duplication of post. How do i delete it? Sorry Rookie user! :D

Many thanks for your post, I am hoping to hear back today from a chap testing my ECU's VAG no ending 557.

It does seem very strange as sometimes it fires for a second and then for maybe up to a max of 4 secs take a few 100ths of a second. Once the engine has stopped firing and I continue to crank the engine it does not fire again unless it disengage the starter and turn it over again. It is at this point that the noid light connected to any of the injectors stops triggering and the pulse in the LED disappears.

It screams immobiliser at me.

I have plugged VAGCOM into it and on the immobiliser block i am getting status 1 for all 3 pre requisites for engine to start.

15:09:36
1 Engine Start permitted
1 Engine (ECU) responds
1 Key/Transponder Status
N/A

Above is extract from saved file for this ABZ.

I had the Immobiliser removed from the ECU and i plugged it back into the loom. Instead of the engine stalling after 1 sec everytime, it ran a little longer for up to 4 seconds. I took the ECU back to the company who told me it must be something else.

Back to the very written on and find another space on the drawing board.

Hope this further explanation triggers a more definitive response from you guys.

Please bear in mind that no matter how significant or not you think your experiences my have been with this problem please do post it as it may help.

Many thanks,

+++

I do suspect a head gasket as I have a little bit of oil in the water tank and the oil is emulsified. Would this stop it running though?

Doubt it. ABZ will chew through most things, for more than 4 seconds anyway... +++

Most people either run a full VAG loom, with original ECU, immo box and key - or they run something completely external like a megasquirt (iirc)

Not seen a VAG ecu, modified to remove immobiliser before. Not that its looking very successful at the moment... ;)

The immobiliser cut out varies between about 1 and 3 seconds. Significantly, it will defintely catch and fire, start running under its own steam and then just die, which sounds exactly what you're seeing to me....

IT,

Many apologies to you all for duplication of post. How do i delete it? Sorry Rookie user! :D

Many thanks for your post, I am hoping to hear back today from a chap testing my ECU's VAG no ending 557.

It does seem very strange as sometimes it fires for a second and then for maybe up to a max of 4 secs take a few 100ths of a second. Once the engine has stopped firing and I continue to crank the engine it does not fire again unless it disengage the starter and turn it over again. It is at this point that the noid light connected to any of the injectors stops triggering and the pulse in the LED disappears.

It screams immobiliser at me.

I have plugged VAGCOM into it and on the immobiliser block i am getting status 1 for all 3 pre requisites for engine to start.

15:09:36
1 Engine Start permitted
1 Engine (ECU) responds
1 Key/Transponder Status
N/A

Above is extract from saved file for this ABZ.

I had the Immobiliser removed from the ECU and i plugged it back into the loom. Instead of the engine stalling after 1 sec everytime, it ran a little longer for up to 4 seconds. I took the ECU back to the company who told me it must be something else.

Back to the very written on and find another space on the drawing board.

Hope this further explanation triggers a more definitive response from you guys.

Please bear in mind that no matter how significant or not you think your experiences my have been with this problem please do post it as it may help.

Many thanks,

+++

I do suspect a head gasket as I have a little bit of oil in the water tank and the oil is emulsified. Would this stop it running though?

IT

Sorry if I seem to of made it cloudy. I am using the original VAG loom with the original immo box VAG part No 4A0 953 234 and a BOSCH ECU with VAG part No 4D0 907 557.

Only after the starting problem with all the immo status on vagcom showing 1 did I then seek to remove the immo. It couldnt really be anything else as everything was connected tested and tested again.

I suspect therefore that the guy who thinks he has removed it probably hasn't then?

Sounds like immo problem. If it is immo then if you turn on ignition and wait 10 sec and then try to start it will not start. If you start it straight after turning on ignition it will start but stall in 2-4 secs.

Is there any fault codes in ECU or immo?

If your friend did immo off in ECU software there would be no need to use immo box at all but that is a memory soldering job. Do you have original key to use with immo box? You might need to pair immo box with ECU or key.

Yes to immo box key and key encoder all matched together via VAGCOM.
I have the following start status on VAGCOM

Address 25: Immobilizer (4A0 953 234 )

17:50:08 Group 001: Immobilizer
1 Engine Start permitted
1 Engine (ECU) responds
1 Key/Transponder Status

If I have these recorded how can it be an IMMO problem? Does VAGCOM lie just the same as a hairy Haynes Manual?

Immo was removed as you say by solder job.

Immo chip removed and replaced with another coded chip!

Regards

Simon

Any fault codes in ECU?

I am no expert but I think You can remove immo on these in main ECU flash or mainflash + EEPROM so that you do not need immo box and key.


Do you have copy of original or modified software?

Having snags getting into ECU at moment, dialouge box on VAGCOM says 'too many communication errors to continue'

I have the ecu's (x3) being tested at a very reputable company. 2 have still got the immobiliser EEprom in them and one has been removed. In some way I am hoping that the one that has apparently been removed has not been done correctly and that this is causing me all of the grief.

My contact who removed the immo has a file to replace the immo software with. Its a de-solder and remove the old chip and solder in a new chip with a free running programme embedded. i'm really hoping that it has the wrong programme on it and that is why it isn't running.