Can I salvage anything from my T5 train wreck :(

[aSimpleLife]

Been side tracked for a while...then first job back I've caused the van stall every time I start it.
It's seemed I've created a fuel problem by using Liqui Moly?

Before trying to remove and clean the EGR valve, to attempt to remove that fault code, I thought I'd attempt using this Liqui Moly cleaner. I was trying to follow this advice in this thread;

https://www.vwwatercooled.com.au/forums/f28/diesel-engine-decarb-117271-post1220020.html#post1220020"

The best way is to unbolt your EGR pipe at the intake flap, with the engine off, and pump that area full. Try and get the hose up in towards the manifold / four inlet ports. Bolt the EGR pipe back up and let it sit for a good while, and then try and start the car, which will take a bit of cranking. It will struggle and run rough till it clears. The next step is to spray it in with the engine running, I do it on idle and just stop as it labours, but I put it in PRE TURBO where the PCV inlet just before the turbo is in the air intake...Put it in anywhere AFTER the MAF and you will get some effect...

However I wasn't yet sure which pipes to remove to do this.

I watched the Supercheap Liqui Moly Diesel Engine video and it was only showing it being used in the inlet manifold/throttle body area. So I thought I'd try that first before I could establish where I should be using it for EGR cleaning. Although my inlet area looked very clean compared to the video. I still used 1/3rd of a can doing this;

https://www.youtube.com/watch?v=3agltbN4C7M



Then took the van for it's longest run so far. About 20km mainly on the freeway. All went well.
I returned home and did some VCDS tests. As a new turbo code had appeared previously. Starting and stopping the van a number of times while doing this.
I did a codes reset before my final test.

Next day I've started the van and it ran for about 10 seconds, sputtered, then cut out.
Tried it another 5 times and it cuts out after 3 seconds each time as if it's starved for fuel.

Left it for a couple of days and have just tried it again.
Same thing happened. Ran for about 10 seconds the first time before sputtering to a stop. Then cuts out after 3 seconds every subsequent time.

Unless it has returned to my previous immobiliser problem...which was similar...but I assume it hasn't.
I have just caused a new problem using Liqui Moly...or by performing the codes reset after this?

I am not sure yet what to try next?

[aSimpleLife]

Right now I still can't get past the van starting, running for 3 seconds and stalling.
This is since the morning after I used Liqui Moly Diesel Engine Decarb spray (although after that, I drove car for 20 mins at highway speeds for it's first big drive in 2 years...started and stopped it several times while vcds testing...and then reset all fault codes).

I now don't believe this 3 second stall is related to the Liqui Moly.
There are no new VCDS fault codes since I used it.
I feel it's a return of the possible immobiliser issue from 2 years ago...which had somehow resolved itself...probably from a reset after 2 years with the battery disconnected.
Back then, I was getting an intermittent engine warning light and limp mode, and my vw mechanic directed me to an auto elec when he had trouble getting vcds to complete and fault codes were appearing which should not have been there.
The 3 second stall problem somehow started with the auto elec...and after 2 weeks he gave up on it too.

I tried a short battery disconnect with no change.

I then disconnected the battery overnight and recharged it (it is an almost new battery).
The one thing different this morning, is the first time it ran for about 8 seconds before stalling. Then after that it was back to 3 seconds every time.
I have noticed this before over the last couple of weeks that I've had this problem.
But don't understand what it might be telling me?

I think what I need to do next is learn how to make vcds turn off the immobiliser.
If I can do this and it no longer cuts out, then I know it's the immobiliser.
If not then it could still be either the immobiliser or Liqui Moly.

Back to the Liqui Moly for a moment.
I believe I sprayed it in the right place.
The large hose I disconnected from the "throttle valve module" ("throttle body") must come from the air intake/turbo making it downstream of these and also of the "Air Flow Meter" (MAF sensor).
I followed the afore linked Liqui Moly video on the Supercheap Auto site and these product instructions.
"This should be positioned downstream of the air flow meter/turbocharger/charge air cooler, where possible directly in front of the intake manifold."

It is still possible the Liqui Moly has coated or damaged a sensor but I am not sure which one or what to do about it?
Perhaps a "Throttle Position" sensor and/or an "anti shudder control" sensor?
I would have expected others to be reporting this though...which I didn't find.
It's been suggested I use a "throttle body cleaner". But which one for a diesel?
I am especially cautious now about spraying anything more inside this engine that I don't understand well enough

And back to the immobiliser.
If it is this, then it is likely a false positive caused by a broken/corroded wire/connector. Apparently not uncommon with TDI's.
Earlier in the thread it was suggested I replace the engine bay wiring loom.
I've watched some videos of people diagnosing and repairing these problems with a a multimeter and soldering iron...I have both of these...but don't know how to use them properly yet.

Next step seems to be to learn how to use vcds to turn off the immobiliser.
EDIT - it seems like I got this option wrong - it's only possible on Immobilizer gen 1 or 2 - my T5.1 2010 must be gen 3 or 4 - and it seems this option is no longer available


A couple of other observations;

- when the engine cuts out...my "Moo" valve seems to have become louder and longer since I used the Liqui Moly. But I don't think its' related to the 3 second cut out problem?

- and also when the engine cuts out...there is a new high pitched sound I don't remember before.
Could it be this "...the TDI makes a high pitched whine for about 20 seconds and this is the shutdown flap remaining closed blocking air from entering the inlet...Its the electronic throttle body unit, it performs a post self test..."?
This is the area where I sprayed the Liqui Moly.
But again it would not seem to cause this 3 second cutout problem.