Power loss 2.0 TDI 125 kW BMN

Hello everyone, and a happy New Year 2017.

I created a post some time ago about a power loss issue I was experiencing with my Seat Leon 2.0 TDI. However, it was missing a support key, which I have now obtained.

The cylinder head was removed from the vehicle due to a persistent overpressure issue in the radiator.
It was planned and completely overhauled. The cylinder head was overhauled, and valve guide inserts were replaced, among other things.
The intake manifold was also replaced because a valve was broken, and the exhaust manifold was resurfaced because it was slightly warped. In the process, the timing belt, water pump, and tensioner were also replaced. Glow plugs were replaced, and the injector nozzles were cleaned in an ultrasonic bath. The nozzles were replaced once during a recall campaign at approximately 120,000 km. The repair was performed at a mileage of approximately 155,000 kilometers.

Since then, I've gotten the impression that it's not as lively as it used to be, and it struggles to reach its top speed. However, I find the fuel consumption (approximately 4-5 liters per 100 kilometers at 60 km/h in fourth gear) to be sensational. He wasn't that small even at the beginning.

VCDS is available, and I have previously recorded data logs for the lambda sensor, mass airflow sensor, and boost pressure, which I can share if needed. The synchronization angle was slightly adjusted by me and is now approximately 0° (previously 1.7° before TDC) at idle.

The workshop that performed the repair says that everything should be okay.

I also need to mention that Bosch service took over the cleaning of the PPDEs, but the nozzles weren't installed until about 5 weeks later.
The lambda values are between 3500-3800 rpm at 1.35-1.37 under full load, which I find a bit too low for cleaned injectors.
However, the boost pressure is approximately 100 mbar below the target value.

I hope I can get some tips or an approach to troubleshooting.

Attached are pictures of the cylinder head and intake manifold.


Sure, here's the translation:

"Best regards."

Flo.

Hi,

PPD components with coking issues should be cleaned starting from a lambda value of 1.40, and yours are only slightly below that.
In the affected engines with PPD components, the injector nozzles become clogged, which prevents sufficient fuel from reaching the cylinders during injection.

The lambda value describes the ratio of air to fuel compared to a combustion-stoichiometric mixture (where all fuel molecules are completely burned with the oxygen in the combustion air).
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

If the lambda value is high, it means there is a low amount of fuel relative to the amount of combustion air.
The values found for your engine are approximately 1.28 to 1.35 at full load in 4th gear. It would be best if you explored the topic yourself by clicking around or using the search function, as there's likely more information available.

If your average lambda value is 1.36, and "new/clean" values are 1.32, then you already have a performance loss of around 3%, which translates to approximately 5 horsepower with 170 horsepower.
Unfortunately, at higher speeds, smaller or clogged nozzle holes have a more significant effect than at lower speeds, which makes a reduced final speed a plausible explanation.

In addition to the PPD elements themselves, proper alignment is also crucial.
/viewtopic.php?t=5408&highlight=pdelemente+einstellen

Quote:

Loosen the lock nut of the actuated PDE and screw the adjustment screw as far as possible into the pivot lever until you feel a noticeable resistance: the PDE is at the lower limit. From this position, turn the adjustment screw counterclockwise by 225° (half a turn plus one-eighth of a turn). Tighten the lock nut to 30 Nm or until it reaches the marking (Appendix 2, Figure 4). (More recent VAG instructions specify that the adjustment screw should only be turned out by 180° instead of 225°. This applies to all PD engines, even if a previous adjustment value of 225° was specified for the same engine.) The reasons behind this change are not known here.)

While this is specifically for the 1.9 PD-TDI engine, it can generally be used for your engine code as well. Use a 180° setting.

Of course, the engine also needs to receive enough fuel, meaning the tandem pump on the cylinder head must deliver enough fuel with sufficient pressure (perform a pressure test!), the diesel filter must be clean, there must be no leaks allowing air to be sucked into the fuel lines, etc.

Make sure the exhaust temperature sensor is securely attached and that there are no exhaust leaks between the cylinder head and the exhaust manifold/turbocharger.
Otherwise, power is lost that would normally be used to drive the turbocharger, which reduces its efficiency and makes the vehicle feel sluggish.
"Also, check for leaks in the charge air system. These leaks often manifest as engine oil/seepage at the leak points. If you have insufficient intake air due to a leak in the charge air system, certain readings will be skewed. You'll see lower lambda values when measured with a lambda sensor, and higher values when calculated using the mass airflow sensor."

Best regards, Rainer.

Hello.

Thank you very much for the quick response!

So, the injectors were adjusted with a 180-degree reverse setting, so it's correct.

I believe the exhaust temperature sensor was also replaced. I will check those, as well as the exhaust manifold and the intercooler system.

I would also like to add that my car barely started this morning, and the temperature was -10 degrees Celsius. The battery is only 3 months old. It took about 20 seconds of cranking before it started.

Sure, here's the translation:

"Best regards," or "Sincerely,"

FloFrtdi wrote:

I would also like to add that my car barely started this morning, and the temperature was -10 degrees Celsius. The battery is only 3 months old. I had to crank it for about 20 seconds before it started.

Then either the coolant temperature sensor is faulty, or you have an air leak in the diesel lines... and the glow plugs are probably new, are they working properly?

Best regards, Rainer.

I will measure the current draw of the glow plugs using a clamp meter and compare all temperatures when the vehicle is cold using VCDS. In this context, I will also check the fuel system for pressure and leaks. However, it should be noted that even after only about 2 minutes of engine running time, the starting process works perfectly! Greetings.

Here's a quick update on the starting issue. My starter motor was only reaching a maximum speed of 190 revolutions per minute. I believe the engine management system only allows the engine to start around 300 RPM. I installed a new starter motor, and now it starts like it's brand new. The glow plugs were drawing full power. The temperature sensor also fits.

FloFrtdi wrote:

Short update on the starting behavior: My starter motor had a maximum speed of 190 revolutions per minute. I believe the starting management system only allows the engine to start around 300 RPM. I installed a new starter motor, and now it starts like it did on the first day. The glow plugs were drawing full power. Temperature sensor also fits.

Great, thanks for the feedback! For the engines I'm familiar with, the minimum speed requirement only applies to starting the engine when it's warm. Of course, a very cold engine that's rotating too slowly will also be difficult to start.

Best regards, Rainer.

Sure, you're welcome. I could hardly believe it myself, but 190 rpm is probably too slow.

Regarding the 100mBar pressure difference, I found a slightly leaky hose at the inlet. I replaced it, and now the pressure is back to where it should be! Now, let's continue with the injectors...

Sure, here's the translation:

"Best regards," or "Sincerely,"