Hubraumvergrößerung bei BDH Motor möglich? | Posts 48+

Hi,

The expansion of Erwin (siehe Fehlerdatenbank) happens automatically, because the question of how to get in touch with him has been asked approximately 1 million times.

Best regards, Rainer.

Hello everyone,

First of all, a HAPPY NEW YEAR 2017 to everyone, and I hope that this forum continues to be just as engaging and entertaining as it was in 2016.

Now, let's move on to the topic.

At the end of the year, I performed a pressure loss test to assess the overall health of the entire crank mechanism.
Result:
Everything is fine below the cylinder head gaskets.
The pressure losses are all below 0%, and this is despite the high operating hours.
I also had the fuel injectors refurbished before Christmas, which, according to the official service manual, is supposedly not possible.
According to the documentation, these are two-nozzle injectors that inject in two stages. They are supposedly non-adjustable and non-serviceable, and therefore must be replaced. However, that's simply not true. I find it really outrageous to spread such falsehoods through the documentation.
The copper rings were replaced, as were the U-shaped steel rings on which the nozzle tensioner is mounted and then secured with two M6 nuts. The torque for the nuts is 10 Nm.

What can I say, I am very satisfied with the performance that is currently available.
What I'm not satisfied with is the variation in fuel injection amounts between the cylinders, the poor starting performance when the engine is lukewarm (around 25-40°C), and the cold start performance. An explanation will follow.

Prior to the replacement of the injectors, all values were in the positive range, between +0.35 and +2.75 ml/cycle. Now, after replacing the injectors and recalibrating the timing of the D-pump to exactly 2° after top dead center (TDC), all values are in the negative range, between -0.8 and up to -5.70 ml/cycle.

When the engine is slightly warm, it starts after about 5-8 seconds and emits a large, white cloud from the exhaust, which smells wonderfully like diesel.

The same thing happens when the engine is cold, but with the difference that it starts immediately, runs roughly for about 2 seconds, and emits a small white puff of smoke from the rear.
After that, everything was fine, a beautiful run. In a warm state, it also provided a beautiful run and very good performance.


Okay, here are my questions:

Do I need to adjust anything on the pump's basic settings now that the injectors have been replaced, or can I use VCDS to adjust something differently to improve the starting performance?
Does the fuel pump remember the last injected amount and adjust it accordingly into the negative range for new injectors?

Do I need to remove the pump and have it inspected, and possibly adjusted?
Or revise it, because it's currently the weakest link in the chain and hasn't been checked yet. I also don't know if the previous owner, or someone else, might have already tightened the central nut on the pump.

Thank you for reading.
Active participation would be great.
HG
Michi.

Hi Michi,

First, the injection amounts are not measured in ml/stroke, but in mg/stroke. Second, the statement that the injectors on the 2.5L V6 TDIs are not adjustable is not an insult, but rather corresponds to the truth for the majority of inexperienced individuals who have no idea what they are doing.

Your post demonstrates that you neither disassembled a nozzle holder assembly nor understand the functions of the parts within it. Therefore, I strongly advise you to refrain from making any provocative statements on this topic.

The nozzle holder combinations are adjustable, but unfortunately very complicated, as changing the corresponding adjustment washers is difficult to impossible, and definitely not worthwhile.

You can tell that you messed up your injector nozzle combination by the smoke when starting the engine and the fuel injection quantity corrections, which were worn but better before your modification, but unfortunately, after the modification, they are completely out of order.
The question of whether anything more should be "tinkered" with the engine when the "injectors are as good as new" is utterly pointless and demonstrates a complete lack of understanding; it's infuriating. No, the pump doesn't remember anything.

And this question has nothing to do with increasing engine displacement, so I'm posting it here.

Despite everything, happy New Year 2017.

Best regards, Rainer.