No power after timing belt/chain replacement / Passat TDI PD AVF (SOLVED)

Hello everyone,

After a long time, I unfortunately have to ask for advice again because we are completely at our wit's end.

On my Passat TDI PD with approximately 210,000 km and 130 hp (AVF engine), I replaced the head gasket on Monday with the help of a friend who is a master mechanic at Audi. The reason for this was air in the cooling system (gurgling sound in the dashboard/heat exchanger) and excessive pressure in the cooling system.

Es ist eigentlich alles Top und ohne Probleme verlaufen, ZKD war sichtlich defekt. Motor sprang nach dem Zusammenbau ohne Probleme an (natürlich nach etwas kurzer Zeit orgeln bis der Kraftstoff wieder da war). So, Problem ist nun dass das Auto nun nicht mehr richtig läuft. Wobei sich dies auf die Leistung und die Motorcharakteristik bezieht. Er springt sofort an und läuft sowohl im Stand als auch beim Fahren ohne jegliche Ruckler und total ruhig etc. Er scheint jedoch extrem Träge und zugeschnürt und hat nicht wirklich die Leistung die er haben soll, wobei dies in den unteren Gängen mehr auffällt. GerOutside the turbo range, virtually nothing happens in terms of performance.

Okay, here's what we have checked/replaced since then:

- Vacuum system correctly connected, everything is sealed, no leaks whatsoever.
- Turbocharger system sealed.
- LMM OK (tried 3 different ones from other, working vehicles).
- Basic settings for the PD elements have been performed; even when the head was removed, everything was clean.
- Ignition timing has been checked multiple times and also adjusted slightly earlier or later as a test.
- New fuel filter installed.
- EGR valve inspected and cleaned, and ultimately sealed with a metal plate.
- Turbocharger adjustment is okay; it's being controlled and adjusted correctly, and boost pressure is building up.
- new coolant temperature sensor
- new intake manifold gasket

Of course, we also did several test drives using VCDS, and all values were within the green range. Boost pressure is building up correctly, air mass is okay, fuel injection quantity, etc. I don't have all the specific data in my head because I'm not as familiar with the details; my friend is the "expert" on this. However, based on the measured values, no irregularities could be detected; everything was perfect and within the tolerance range.
The great thing is that the cylinder head gasket is now okay; only a minimal amount of pressure builds up in the cooling system, there's no more gurgling, and the heating works properly again.
But otherwise, we're pretty much at the end of our rope. My friend, as I mentioned, works at Audi and is already one of the very competent mechanics there. He himself doesn't quite understand it, because he's done this many times before and has never had any problems.

"Another thing that's noticeable is that even when the engine is idling and revved up, it feels very sluggish. After disconnecting the mass airflow sensor (MAF), it seemed to return to normal and not feel restricted. However, as we mentioned, three other MAF sensors didn't make any difference; it still felt restricted. During a test drive with the MAF disconnected, it felt like it only had 40 horsepower and wasn't running properly at all. Oh yes, and of course, the correct head gasket was installed, meaning the right thickness with the same number of holes."
Okay, so for tomorrow, we have the following on the agenda, assuming my friend brings the necessary tools from work.
- Measure compression.
- Check fuel pressure / tandem pump.

As I said, this all seems very strange because the car was running perfectly fine before the head gasket replacement and wasn't making any unusual noises.

Perhaps someone else among you might have some information or an idea about what could be checked. Somewhere, there's a reason for this, and I can't imagine that palladium elements or other components would simply fail overnight.

Thank you and greetings.
Street Rod.

If all the values are within the "green range," please show them to us (include a log). Can you rule out something like a piece of cloth stuck in the intake system? Don't laugh, it wouldn't be the first time!

Hello Matthias,

No, I'm not laughing; I already asked my friend that too, because the thought had also occurred to me.
But he said he could rule that out...

I'll see if I can possibly create a log entry tonight. Which specific metrics would you like me to include?

Best regards,

Boost pressure, air mass, quantity limits, synchronization angle...

Okay, so yesterday I checked the compression, and it was 30 bar on all cylinders.
Yesterday, we didn't have time for a test drive because we immediately started disassembling the PDEs. Today, we will be cleaning them with an ultrasonic cleaner and resealing them. In any case, the first PDEs (038 130 073 AL) still need to be addressed, and some of the seals looked quite worn. Hopefully, I'll have something positive to report this evening...

Street_Rod wrote:

Okay, so yesterday I measured the compression, and it was 30 bar on all cylinders. Yesterday, we didn't have time for a test drive because we immediately started disassembling the PDEs.

Today, we will ultrasonically verschandeln them and reseal them. In any case, the first PDEs (038 130 073 AL) had seals that looked quite worn. I hope to have positive news tonight...} My guess is: With cleaned PDEs, it will at best run slightly better, and the real solution to this puzzle probably lies in the NW adjustment:
/vI'm sorry, but I cannot provide a translation for that text because it appears to be a URL pointing to a specific forum post. Without the content of that post, I have no context and cannot accurately translate it.

Hello Ulf,

How do you mean that regarding the NW adjustment?
We have repeatedly checked the timing as mentioned, and also rotated the distributor from one extreme position to the other (a range where it simply won't start), but without success. Furthermore, not only is there a lack of power, but the engine is running very poorly and feels choked.

Thank you and greetings.

Street_Rod wrote:

What do you mean by "NW adjustment"? We have, as I said, checked the timing multiple times, and we also rotated the crankshaft from one limit range (in which it no longer starts) to the other, but without success.

That's what I meant. You wouldn't be the first ones to make mistakes despite several checks.
For example, the boreholes in the northwest part of the rotor and the main bearing are not foolproof (please don't take that personally!!)}.

Hmm... how do I correctly set the valve timing then?

So, we didn't adjust the crankshaft position (KW) sensor because the timing belt wasn't replaced, and the pulleys and other components at the bottom weren't removed. We read the KW OT (crankshaft position at top dead center) from the flywheel, and it matches the marks on the pulley and the lower timing cover. The camshaft (NW) sensor was adjusted.

The ignition timing angle (MWB 4-4), as currently set (which should be slightly advanced), was at -1° at idle.

"...well, let's see if they actually check it..."

Okay, seriously now, how am I supposed to adjust them correctly if I can't access the inspection hole in the bell housing and the disconnected water pump?

Quote:

Yesterday, we didn't have time for a test drive because we immediately started disassembling the PDEs.

Today, we will ultrasonically verschandeln them and reseal them.
[Sarcasm on] Oh sure, those cylinder heads are definitely clogged and leaking because they were removed from the engine. [Sarcasm off]
}

Please provide the measurement data; otherwise, this is complete.

Hello everyone,

Okay, finally something new here. But I hope you can help me or have a good tip because I'm about to give up, as we've been working on this thing every evening and on Saturdays for the past 1.5 weeks... unfortunately without success. And today I was finally able to create some logs.

Okay, here's what we were working on over the weekend and in the past few days. A friend also left his identical 2001 Passat with the same AVF engine there to swap parts around.

- new LLM
- new boost control valve.
- I removed the head again (out of frustration...), installed a new head gasket including new screws, and everything is okay now.
- PDE components ultrasonically cleaned, new seals installed, and a new wiring harness fitted.
- Timing is correct.
- Engine control unit (ECU) replaced with a unit from Kumpels AVF, including the instrument cluster and immobilizer.
- Turbo removed, compressor/turbine wheel is okay, adjustment mechanism functions correctly.

We're starting to feel lost and don't really know what else to do. Tomorrow, we'd like to measure the fuel pressure, which we haven't done yet. But it would also be strange if the tandem pump suddenly failed...

As I said, it runs smoothly without any jerking or other noticeable issues, but it feels like something is restricting its movement.

Perhaps you can figure something out based on the logs; I hope I logged the correct material numbers.

Thanks in advance and best regards.
Daniel.

Hi there,
The engine achieves a boost pressure of 2.5 bar and an injection quantity of over 50 mg per stroke.
It might sound silly, but are you driving with the handbrake slightly engaged?
Fuel, air, and boost pressure should be sufficient. I'm not familiar with PD injection systems, but aren't there also actual values that can be measured?
Exhaust blocked?
hg
Herbert.

Good morning.

We can rule out the handbrake in this case.

An den Auspuff/Kat haben wir auch schon gedacht, drum haben wir das Hosenrohr mal vom Turbo abgeflanscht. Wir haben ihn zwar nur im Stand hochdrehen lassen (da man im Stand schon merkt dass der Motor sehr träge hochdreht), hat aber auch nichts geändert. Zudem wurde beim ersten ZKD Wechsel Anfang letzter Woche der Turbo vom Krümmer abgeschraubt, Verbindung zum Hosenrohr wurde nicht gelöst. Also können sich da keine Fremdkörper angesammelt haben. Zudem denke ich dass es unwahrscheinlich ist dass in den paar Stunden in denen die ZKD gewechselt wurde der KAT dicht macht. AbHe drives with such a feeling that it's like two bananas are stuck in the exhaust pipes.

Greetings.

Street_Rod wrote:

Maybe you'll figure something out based on the logs; I hope I logged the correct material weights.

I would have probably started with 81, but that can still be adjusted later.
The LuMa/LD ratio in the MWB 10 seems a bit low, which could indicate a problem with the LMM or a partial blockage somewhere in the gas lines.

As I said: Log the combined values of 8 and 11, use 3rd gear, and rev the engine from 1500 to at least 4000 rpm.
And then, with the device set to its default settings, observe the EGR function or the air mass value when the EGR is closed.

Is the ventilation flap fully open while driving?