ARL: Delayed boost pressure build-up again

Hello,
I'm still experiencing the problem where the turbocharger builds boost very slowly.
When accelerating, there's initially no response, and then it starts to pull (around 2200 RPM), but I think it used to be much more powerful. Even when suddenly flooring the accelerator, the engine takes 1-2 seconds before anything happens. The maximum speed is no longer reached (it's about 10 km/h lower).
The following items were checked:
- Vacuum system and LD control valve (replaced) - OK.
- LLK system. LLK and connections (no leaks, no oil seepage) - OK.
- Replaced the LMM (mass airflow sensor) with one from a Golf 5 that has two grilles (new air intake).
- VTG (Variable Transmission Gear), operates with noticeable resistance when adjusted manually, but functions without issues under vacuum (from minimum to maximum).
- New air filter.
- New fuel filter.
Specifically in the higher gears, the acceleration (at 100% load) noticeably decreases and then resumes.
The only possible causes that come to mind for me are the turbocharger (I still have the old 038 235 016D from the pre-production series), the fuel pump, the feed pump (which is MISSING so far), or the PDE elements.
Was ich noch erwähnen möchte, das ganze wurde in eine Golf 3 Verpflanzt, die Vorförderpumpe und der Dieselkühler wurden dabei nicht mit verbaut. Der Wagen hat aber mal gut funktionier (bis 200kmh etwa wie beim VR6)! Kann es auch daran liegen? Habe mir den Dieselkühker und eine Dieselpumpe aus eine Passat 130 PS TDI und einem Polo SDI Besorgt, aber noch nicht verbaut und werde diese Kombinierun und nachrüsten und sehen was passiert. Was sagt Ihr darzu (wie wird die tatsächlcihr Einspritzmenge erfasst, berechnet oder gemessen)? Messfahrten habe ich einige durchgeführt, der max. IST Ladedruck bertägt 2560 mbar, was für einen intakten Lader und intakten Kat spricht (das Taktverhältniss liegt bei max. 70%). Der LMM Wert ist zu gering (max. 1160, sollte bis 1249 gehen) aber warum? im Bereich bis 2200 RPM ist das Rußkennfeld aktiv (liegt also über der Drehmomentbegrenzung) warum? Kraftstofverbrauch ist normal, kein Ruß, kein nennenswerter Ölverbrauch. AGR ist per Stahplatte inaktiv. Im Steuergerät wird kein Fehler abgelegt, der Wagen fähr sich wie mit ca. 120 PS mit deftigem Turboloch, kein Chiptuning. BitI would appreciate your help; I can gladly provide measurement protocols if needed.
I'm looking for advice. The car feels "sluggish" and the engine is too weak for the performance and weight. Since there are many TDI experts here, I know this conversion is rare, but I hope you have some ideas on how to proceed. I think the turbo might be the issue; it's an engine from a VW test vehicle, and the only available turbocharger is the 038 253 016G (which comes in five different versions with slightly modified bearings). Please help me.

Here's the translation:

"First of all:"

Logs, logs, logs.

You seem to have some, so go ahead and share them (somewhere on a web space and link them here).
Because if you can completely do the log analysis yourself, then you no longer need us .

Quote:

In the range up to 2200 RPM, the soot map is active (and therefore above the torque limit)

.

"It shows, however, that you need us after all (which is perfectly okay)." Because this conclusion is incorrect.
Strictly speaking, the Russian character set is passive and resides in the EEPROM. Active can only be the current value. And "active" means that it's the limiting factor, and it's only a limiting factor when it's below other values.

Therefore:

Logs, logs, logs.

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Here are the compiled logs; let's see what we can learn from them.

Zak1976 wrote:

Here are the compiled logs; let's see what can be learned from them.

For me:
A lot of irrelevant data, but no suitable test for your specific problem.

Try shifting into a high gear (5th or 6th) while coming out of the low-rpm range, and floor it at a maximum of 1200 rpm, logging data from 3rd, 10th, and 11th gear to above 2000 rpm. This will allow us to closely examine the behavior in the lower RPM range across multiple data points.

"The tuning will be finalized and posted tomorrow, but even now, some things are noticeable. In my opinion, the maximum air mass value is too low, although the boost pressure (once it's regulated) seems to be okay. What's a bit strange is the significant overshooting up to 2.8 bar and the constant adjustment when I release the throttle. Also, the fact that the soot limit is used as the control variable in the lower RPM range surprises me. Could this be related to insufficient fuel supply, or can we rule that out? I'll send the new logs tomorrow."

"Hey everyone, here's the requested log data from the MBW 3-10-11, recorded in sixth gear while driving at a constant speed. During this test drive, I also noticed two instances of power loss, which I was able to reproduce."

Zak1976 wrote:

Here is the requested log of the MBW 3-10-11 from the RPM range at low speed in 6th gear.

Okay, but unfortunately, I made a mistake in the MWB: 008 should have been included with the limitations, which are 3, 8, and 11 .

Well, even like this, you can see that the boost pressure in the engine isn't too bad: it reaches the target value at around 1500 rpm, and that's still acceptable for an ARL, I think.

According to the data log, the measured air mass is exceeding the torque limit starting at approximately 1500 rpm. Therefore, even with a better mass airflow sensor (MAF), I don't expect to see a significant increase in power output.

However, a log from a similar vehicle (MWB with the same driving profile would provide more accurate information.

What do you think about the two instances of overboost (200 mbar is quite a lot, and improper adjustment can cause this), which I haven't seen before? Also, the overshoot from around 2100 rpm in the previous logs has disappeared. Where does that come from? This was also my first test run in the highest gear. It looks to me like the boost pressure control now has more time to adjust. My other logs were done in 4th gear, where the fluctuations are larger. Could this be related to a defect in the engine control unit (ECU)? I have some older logs where the maximum value of the mass airflow sensor (MAF) is 1249, which doesn't seem right.
Measurement data will be available tomorrow.

Zak1976 wrote:

What do you/do you all think about the 2 misfires (200mbar is quite a bit, and poor gas tuning would eliminate that), which I haven't had before? Also, the overshoot from the last logs at around 2100 is no longer present. Where does this come from?

IMO, the issue is either caused by a jammed VTG (Variable Transmission Gear), a "regulation offset" due to incorrect VTG rod length, and/or the duty cycle of the MSG (Main Signal Generator) is not compatible with the hardware of the LD (Load Detection) control system (which in turn could be due to hardware defects or the initial causes mentioned).

Dealing with something like that is often difficult.

What perfect weather for a dyno test! Here are the logs. Is it normal that the soot limit is being reached when the engine is running at low RPMs?

"Dehzahlkeller" is a term that doesn't have a direct translation without more context. It likely refers to a specific type of cellar or storage space. Without knowing what "Dehzahl" refers to, it's impossible to provide an accurate English equivalent. It could potentially be translated as something like:

* "Dehzahl-type cellar"
* "Cellar with Dehzahl features"
* "A specific type of storage cellar"

But these are just guesses.

The Russian border doesn't open until 2000!

That is definitely not correct!

The mass airflow sensor (MAF) is showing low readings. If you bypass the EGR valve (to prevent it from interfering) and replace the MAF sensor with a diode, you will experience the full potential power output.

But 850 mg/H for the ARL seems strange; what's left from the G3 in that case?
Beim ARL haette ich Wert ueber 1000 als Max. Expected.

My 1Z starts at 700 RPM, and when I turn the diesel injector on, it only injects 35mg.

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hi, that's exactly what I mean. Up to 2000 RPM, the fuel injection quantity is limited by the values of the soot map. Ulf explained in the previous topic that the "850" refers to the mass airflow sensor (MAF) value, which is a limit from the EGR map and is irrelevant at full throttle. The MAF values are definitely too low; about half a year ago, the actual values at 100% load were still around 1249. The MAF sensor is new, as is the boost control valve. The EGR system is deactivated, there's no more soot... I checked the VTG (variable turbine geometry); when I suck on the vacuum hose, it goes to its maximum position without making any noise. For some reason, the boost pressure builds up too slowly and unevenly. I notice a momentary loss of acceleration just before 2000 RPM and immediately after, which is also visible in the log. I suspect the turbocharger, the high-pressure pump/injector, or the fuel supply, possibly even the engine control unit (everything that Gled costs). Basically, only the body shell is from the Golf 3; everything else comes from the donor vehicle (the pre-lift pump and diesel cooler are the only parts that haven't been installed yet).
Also, I also got a mass airflow sensor (MAF) from what I believe is a Golf 5, as a replacement – the type with the two grilles because of the modified air intake and its supposed increased lifespan. However, it didn't make any difference in terms of performance or measured values.
"The professionals, you can probably say something about this."

Zak1976 wrote:

The LMM values are definitely too low; about half a year ago, the actual values at 100% load were still 1249. The LMM is new, as is the turbocharger control valve; the EGR is deactivated, there is no more soot... I have checked the VTG; when sucking on the vacuum hose, it goes to the maximum position (without sticking). For some reason, the boost pressure builds up too slowly and unevenly.

Well, here we have the classic "chicken or the egg" dilemma: which came first?
Is the blower stuck, which is why the air mass isn't rising in the basement, or is the mass airflow sensor (MAF) reporting too low a value, which is why the soot limit is being triggered for so long?

Given the extremely low LMM (lambda-by-mass) values even with full boost pressure, I would lean towards the latter explanation.

Just to be on the safe side, have you ever removed the hose at the compressor inlet and tried to see how easily the impeller spins?

If it's not due to the charger, then IMO (In My Opinion) should be considered.
-> Intake of "false air" between the mass airflow sensor (MAF) and the compressor.
-> Bottlenecks throughout the entire exhaust system (air filter clogged, catalytic converter blocked, intake manifold dirty, catalytic converter choked, muffler crushed, and everything else that could possibly go wrong).
-> The LMM is receiving insufficient supply voltage.
-> Oh yeah, and of course, the classic "LMM defect". Even almost new parts don't really offer protection against that .

Have fun continuing your search .

Okay, good. To test the LMM, I'll perform the diode test tomorrow.
"I've completely removed the turbocharger. I would say the play and smoothness of the shaft are okay, and visually there's nothing noticeable on the charger itself. The intake manifold had some minor deposits, but nothing major. During installation, all seals were replaced, and the EGR system was disabled."
Regarding "false air" intake, would I still be able to achieve full boost pressure?
The same question arises regarding the issue of bottlenecks.
The thing about the voltage at the mass flow meter sounds interesting, how high should it be?
How can I activate more professional mechanics besides Ulf (thank you again, Ulf, for everything so far)?

Zak1976 wrote:

Regarding vacuum leaks that allow "false air" to enter, would I still be able to achieve full boost pressure?

As long as the residual airflow measured by the mass airflow sensor (MAF) raises the soot threshold sufficiently so that the turbocharger receives enough boost -> yes.

Quote:

The thing about the voltage at the LMM sounds interesting, how high should it be?

Read articles on LMM technology.

Hello,
habe heute endlich Zeit gefunden den Diodentest durchzuführen. Ergebnis, der Wagen verhält sich so wie er soll, Ladedruckverlauf sieht sauber aus und in keinem Bereich ist die Rußgrenze die Regelgröße. Würde ja gerne so weiterfahren aber nach einer gewissen Zeit geht das Steuergerät in den Notlauf mit der Meldung "Ladedruckregelung - negative Abweichung", warum auch immer. Damit könnt es ja der LMM sein. Dieser ist neu und brachte genau die Werte von dem alten, was schon ein sehr großer Zufall ist. Nochmal an euch, mal angenommen zwischen Turbolader und Luftfilter befindet sich ein Leck könnte das doch genau zu diesem Verhalten führen oder? Dies könnte auch ein Beweis dafür sein das der Diodentest fehlerfrei verlief (wenn mann annimmt, das der LMM intakt ist). Duch den max. LMM Wert den die Diode vortäusch wird die max. Karaftstoffmenge eingespritzt, die Rußgrenze ist nicht die Regelgröße da genug Luft und Ladedruck vorhanden ist, die in dem jeweiligem Drehzahbereich mögliche Kraftstoffmenge Rußfrei zu verbrennen. Ein Leck im Ansaugbereich würde nicht auffallen, da der LMM Wert ja immer max (1249) ist. Wenn wir jetzt von einem Leck im Ansaugbereich ausgehen (bei intaktem LMM) würde (obgleich ja genug Luft da ist) der LMM eine zu kleine gemessene Luftmasse messen, dies verursacht dann eine Nachregelung, die zu träge ist und deshalb wird das Rußkennfeld das Regelkennfeld für die Einspitzmenge. Was What you mean.
Attached again is the log file with the diode information; it appears to be as expected.