2006 MK5 Golf 2.0 TDI (BKD Engine) - Possible Misfiring

[Gangerman]

Hello to one an all,

I have a MK5 2.0 TDI VW Golf BKD Engine that is giving me some grief.

Mileage: 236,xxx Km

I will attempt to keep this description concise and as brief as possible.

It all started out perhaps 6 months ago, occasionally when pulling off the car would feel like it wanted to stall - shudder a little but never actually did cut out on me, this was I guess a slight nuisance if that, and never really occurred with such regularity that I felt like digging deeper into the problem.

Perhaps a month to 6 weeks after that, the first occurrence of what is the major/consistent issue that I have happened which is: car operating/driving normally without any known trigger on my part and it will start to shudder/judder particularly when the accelerator is applied, this can get very heavy and violent if the accelerator is continued to be pressed to the extent that I have always had to back off the pedal. After this occurred once or twice I probably by fluke found out by turning off and on the ignition this issue could be reset, and the car would immediately go back to driving fine until the issue would occur again. As time has progressed the time between resetting the fault and the fault re-occurring has decreased and decreased to the point where it could happen every quarter of a mile.

I have had the opportunity to plug the car into VCDS, the reoccurring faults are P1263,1267,1269 PD Injector Unit Implausible Signal these tend to occur at any one time for 3 cylinders, never all 4 cylinders together but it can be any combination of the 4 cyclinders (no cylinder is immune so to speak), the fault doesn't occur when the car is cold, it is always at least warm when the fault occurs, as mentioned the fault can always be reset by turning off and on the ignition and even on one occasion whilst I had VCDS up I was able to 'Clear codes' via VCDS and this reset the fault until it happened again.

Attempts to rectify So-Far:

- Replaced injector/glow plug wiring loom under rocker cover (Genuine VW Replacement)
- ECU has been swapped (Step taken by local Auto Electrician)
- Resistance/Continuity Check of wiring between injectors and ECU
- Checked lift pump in tank for any blockage
- Checked wiring looms around the engine bay to check for any chaffing of cables but none to be found

Where should I go next?

Fuel Supply - Tandem Pump? Am I correct in saying there is no way to check fuel pressure with VCDS for this engine?

Help greatly appreciated,

Thanks in advance.

[Crasher]

Was the fuel in the tank black? There is no fuel pressure sensor on the BKD, just temperature.

[Gangerman]

Hi Crasher,

Yes, at the time I had recently put a fuel additive in (Redex if I recall correctly) and had put the discolouration down to that?

That tank of fuel would be gone out of system now, is it worth removing the fuel filter cover to check for discolouration there now?

Thanks

[Crasher]

Yes, that is the next step, I expect the fuel in the filter will be very oily.

[Gangerman]

Ok, I have checked the fuel filter/fuel filter housing, some pictures attached below, thought it might show signs of more oil?

IMG_003.jpg
IMG_002.jpg
IMG_001.jpg
IMG_004.jpg

[Gangerman]

Would this be leading towards a Tandem Pump issue?

[Gangerman]

Healthy_Condition_01.jpgHealthy_Condition_02.jpg
Fault_Condition_04.jpgFault_Condition_01.jpgFault_Condition_02.jpgFault_Condition_03.jpg
Just adding some VCDS data in non-fault and fault conditions might help someone shed some light on this:

First 2 pictures show healthy condition
Next 4 pictures show various fault conditions, just a side note all 4 'INJECTOR STATUS' were reading 128.0 when fault first occurred this pictures was taken shortly after when I had pulled the car over to side of road.

[Crasher]

Fit a clear piece of fuel line in the return from the fuel temperature sender.