Keine Leistung nach ZKD Wechsel / Passat TDI PD AVF (GELÖST) | Posts 16+

Hello Ulf,

Okay, thanks for the info. I'll log 81 again tonight.

We can definitely rule out the LMM (lambda measuring module) because we still have a new one for testing, and it didn't seem to make any difference. I'll also take another look at the shut-off valve and check the air intake paths.

Danke u. Regards,
Daniel.

Street_Rod wrote:

We can definitely rule out a faulty mass airflow sensor (MAF) because we still have a new one for testing. It didn't seem to make any difference at all. I will also re-examine the shut-off valve and check the air intake paths.

Low MAF values can also be caused by vacuum leaks between the MAF sensor and the compressor: Double-check this area carefully for loose hoses, cracks in the intake manifold, etc.

Okay, today I checked the fuel pressure again, according to the specifications at 4000 RPM and 85°C water temperature. It reached 7 bar, which is at the lower limit, but I can't imagine that it's responsible for the problem. I ran the logs in MWB 8-11 twice and did a basic setting adjustment in MWB 3.

We then managed to assemble the car as far as possible and took it home because we weren't sure what else to do, and my friend has a lot of work to catch up on since he had postponed quite a bit.

Interestingly, for whatever reason, it ran better today than after the head gasket change (although, as mentioned, we only checked the fuel pressure today), but still not nearly as smoothly responsive as usual. However, I was able to detect a distinct "thumping" sound under pressure today; no direct misfire, but a slight... well, I'm calling it a "thump."

I was thinking of draining and flushing the engine oil cooler on Friday. It probably wouldn't hurt after 213,000 km, what do you think?

Danke u. Regards,
Daniel.

Hello.

I am very interested in this thread.
Habe an einem 3L Lupo MKB ANY mal den Motorblock wegen lagerschaden erneuert und habe seitem genau dasselbe Problem wie du. Motor lief trotz Lagerschaden mit voller Leistung und jetz mit neuem Rumpf plötzlich nur noch 50% Leistung. Ich habe genau wie du wirklich ALLES geprüft ausgetauscht und nochmal und nochmal kontrolliert und messfahrten und LOGS gemacht. NW einstellungen , Steuerzeiten, PDE, Kraftstoffdruck, LMM 3x neu, Ladedrucksensor, Turbo, Magnetventile, Filter, Drücke, Kompression, Kat und und und. Wagen Rußt kein bisschen also ist die Einspritzmenge zu gering. NSure, why not...?
I haven't found a solution yet, and I'm at my wit's end. I even submitted the MSG for review and received confirmation that it was okay.

I'm rooting for you to find the error. Don't give up, even if it's difficult. Sometimes you can't see the forest for the trees. Good luck, and please keep us updated.

Street_Rod wrote:

I've done the logs in MWB 8-11 twice and have a basic setting in MWB 3.

Although the EGR is defective, it certainly has nothing to do with the WOT (Wide Open Throttle) problem.

MWB 8 + 11 confirm my suspicion that something is wrong with the gas pathways: consistent with the slightly low lambda value, the engine starts very hard right at the edge of misfire, without the usual margin for error typically seen in the OEM setup.
It also seems that, with the LD-TV system, the VTG (variable geometry turbine) needs to remain more closed than usual, towards its maximum power setting, in order to maintain the desired LD (load demand).
A universal explanation that might fit could be something like a piece of fabric stuck somewhere in the air intake or even in the exhaust system.

Quote:

I thought I'd drain and flush the engine oil cooler this Friday; it probably wouldn't hurt after 213,000 km, or what do you think?

But it won't make much difference anyway – unless that speculative piece of fabric has been pushed all the way into the engine oil cooler.

Good morning.

Quote:

The EGR valve is definitely broken, but that probably has nothing to do with the WOT (Wide Open Throttle) problem icon_wink.gif

What does that mean, or what is WOT?

Okay, this weekend I'm going to completely disassemble the intercooler system again, starting from the turbocharger, along the crossbeam, and down to the intake manifold. I'll carefully inspect everything and give it a good cleaning. I'll also flush and blow out the intercooler itself.

I really have to cling to every last bit of hope that's left.
"There shouldn't be anything in the exhaust manifold, because when we replaced the head gasket the first time, we didn't actually detach the turbocharger from the downpipe; we only loosened it at the manifold. My friend also said he didn't put any rags anywhere, but everyone can make mistakes, so I'll take everything apart at the front this weekend."
If the car had been disassembled and left standing overnight, I would have said that perhaps a mouse or other rodents had crawled into the intercooler system and were now sitting in front of the intercooler .
"A little fun is necessary, otherwise I think I'm really going to crack up soon... Thank you, wingmaster, for the encouraging words; I can really use them right now. "

I will definitely keep you updated, and I hope to be able to share some good news with you soon.
What's really puzzling me is why the car actually ran much better yesterday than it did in the days before, even though we didn't change anything about the timing or anywhere else.

Greetings from Bavaria.
Daniel.

Street_Rod wrote:

What does that mean, or what is WOT?

Wide Open Throttle = full throttle.

EDIT

Quote:

So, I'm going to take the time this weekend to remove the intercooler system from the turbocharger down, through the charge air cooler (IC), and up to the intake manifold again. I'll carefully inspect everything and also give it a good cleaning. Additionally, I'll flush and blow out the IC. I really have to cling to every last straw that's left...

Can you rule out the possibility that the problem is caused by a piece of debris lodged behind the "air intake," such as a small cloth stuck in one of the separate suction channels leading to the inlet valves?

"Yep, we had to remove the intake manifold twice because I didn't install a new gasket the first time. Since it wasn't running properly then, we installed a new one there, even though the old one didn't look completely worn out. We did this to rule out that as a potential problem."

Best regards,

What does the soot pattern look like for the rear cylinder when accelerating at full throttle? It's possible that even a slight haze could be visible in the opacity, indicating a potential issue – IF the amount of fuel being injected is as high as the logs suggest.
However, if a simple test using a piece of paper reveals absolutely no soot even when the engine is running at full throttle, then something is likely wrong with the diesel fuel supply – in addition to the already strange readings regarding boost pressure and air intake.

Good morning.

I'm not entirely sure, but I thought that when you briefly accelerate and rev the engine while the car is stationary, there should be a small amount of black smoke emitted? That wasn't the case this time, but I'll check again today. I haven't driven it myself yet. The only exception was recently at night when my wife was driving, but I wasn't paying attention then.

I'll definitely take another look before I expand the LLK (likely referring to a liquid cooling system). As mentioned, I want to do this today and also thoroughly clean, flush, and let the LLK dry overnight, as well as inspect the traverse for any foreign objects. Although I highly doubt I'll find anything there.

I've also been thinking about the fuel supply issue.
"The pre-injection pump starts when the ignition is on - the tandem pump builds pressure (although at the lower limit). The diesel filter is new. Where could there be a blockage between the diesel filter and the injectors? I really don't want to replace the injectors because they are very expensive. Besides, they were working fine before; we only made basic adjustments and cleaned them with ultrasound."

"Where could the bottleneck be, or what might have gone wrong, especially concerning the head gasket replacement? Oh, and my wife mentioned that according to the display, it's currently not possible to get the fuel consumption below 10 liters per [unit of distance]."

Danke u. Greetings.
Daniel.

Before disassembling the intercooler system, check for any leaks (e.g., a clamp that isn't properly tightened or is only on one side, a crack in the connection, oil mist, etc.).

Street_Rod wrote:

The tandem pump is generating pressure (although at the lower limit) -

Did you remove it from the ZK (rotary vane compressor)? (-> Could there be a misassembly during reinstallation?)

Quote:

New diesel filter. Where else could there be a blockage between the diesel filter and the injectors? Where could the bottleneck be located, or what might have gone wrong, especially in relation to the head gasket replacement?

Could any hoses between the fuel filter and the tandem pump be incorrectly connected? Is the diesel sensor installed in the supply line instead of the return line?

Quote:

Oh yes, and my wife mentioned that according to the advertisement, it's currently not possible to get it for less than 10L.

matthiasTDI96 wrote:

If the nighttime fuel consumption is significantly lower than the average reading since the engine overhaul, you have a supply problem somewhere.

Before disassembling the charge air path, check if there is any leak anywhere (clamp not properly tightened or unevenly applied, crack in the connection...oil mist...etc.). The MWB10 log seems to indicate quite the opposite: low mass airflow/charge pressure doesn't suggest a leak in the pressure area, but rather a restriction.}

You are absolutely right, Ulf.

However, when disassembling it, you can still check to see if everything is okay. I mentioned quite early on that a blockage couldn't be ruled out.

My answer might have been described incorrectly.

I wanted to refer to:

Quote:

Where could the bottleneck be located, or what might have gone wrong, especially concerning the head gasket replacement? Oh, and my wife mentioned that according to the display, it's currently not possible to get it below 10 liters

.

And don't rephrase it in a similar way to your explanation.

Hello everyone,

Okay, I'd like to share some updates on the latest, and sometimes mysterious, findings...

Yesterday, I disassembled the charge air system, removed the intercooler, and cleaned it. I also inspected the crossbeam for foreign objects, but found nothing. I steamed out the intercooler and then blew it out with compressed air, letting it dry a bit. Again, no significant contamination was visible. The connections at the tandem pump are all correctly routed and connected (temperature sensor in the return line ).
Today, we pressure-tested the intercooler system; it's completely sealed and without any leaks. We also blew out the diesel lines with compressed air to ensure that any dirt or debris is removed. Finally, we installed a used but fully functional, identical turbocharger that my friend had in stock.

None of the measures we implemented in recent days resulted in a noticeable improvement or had a significant impact, however, there was some improvement with the new trailer. It seems to be working slightly better than the old one.

Was jedoch im Allgemeinen komisch ist, dass das Auto anscheinend von Fahrt zu Fahrt besser läuft. Meine Frau war am DO und FR mal einkaufen, und ich hab gestern nachdem ich den LLK wieder eingebaut habe, ne Probefahrt gemacht. Heut bin ich auch nochmal ca. 40-50km gefahren. Am ehesten hat man wie gesagt noch den anderen Turbolader gemerkt, und ich muss sagen dass er fast schon wieder so wie vorher läuft. Es fehlt ihm jedoch noch etwas an Biss und Spritzigkeit und wirkt obenraus noch etwas träge. Z"However, it still exhibits a slight shaking or vibration under load, particularly in the boost pressure range."

My suspicion is that one of the power steering electric pumps (PDE) might have a defect, which could possibly explain the slight jerking/vibration. In the MWB13 data, one PDE deviates slightly from the others. Three are at approximately -0.5 mg/stroke (I hope I'm using the correct "unit" here...), while the other is at approximately mg/stroke. Although it's still within the tolerance range according to VCDS, it's definitely a measurable deviation.

Was ich auch noch etwas komisch finde ist der Förderbeginn im MWB4. Dieser liegt bei 1,2° n. OT und ändert sich auch keineswegs wenn man die Nockenwelle etwas nach früh oder spät verstellt. An meinem Kumpel seinem AVF liegt dieser Wert bei 4° v. OT.
I unfortunately didn't have a USB stick with me today, otherwise I would have logged data again during the ride at points 8, 10, 11, etc. I was curious to see if you could detect any difference, but I will try that again next week.

As I said, it is currently drivable and has acceptable performance again, even though it's not perfect yet. Unfortunately, I can't explain why... I will let you know if anything new happens. Of course, I appreciate any further tips!

Thank you for listening/paying attention .
Best regards,
Daniel.Unfortunately, I didn't have a USB stick with me today, otherwise I could have logged data at points 8, 10, 11, etc., during the trip. I was curious to see if you would be able to detect any differences. However, I will try again next week.So, as I said, it's currently drivable and has acceptable performance again, even though it's not perfect yet. Unfortunately, I can't explain why... I'll let you know if anything new happens. I would definitely appreciate any further tips!Thank you for your open ears/eyes }.Regards,

Street_Rod wrote:

What I also find a bit strange is the start of injection in the MWB4. This is at 1.2° before top dead center (BTDC) and doesn't change at all when you adjust the camshaft slightly earlier or later. On my friend's AVF engine, this value is 4° BTDC.

I don't know what you consider to be the start of injection.
The actual start of boost is speed and load dependent, and varies depending on the engine and data status, typically within the range of 0 - 20° vOT (crankshaft angle before top dead center), regardless of the NOx adjustment.

The synchronization angle (target range: -3° to +3°) changes only minimally between idle and maximum power, and it is the diagnostic parameter for adjusting the camshaft timing.

Please create a PD log with the following parameters: 13-18-23, in the LL (likely referring to a specific location or system).