Leistungsmangel und ultrahoher Verbrauch beim AEL-Motor | Posts 16+

Hello,

Does the wastegate close properly?
If b) the air mass values are too low, and the engine is therefore constantly operating at the soot limit, the boost pressure will also remain unchanged because the turbocharger lacks the necessary drive power.

Best regards, Rainer.

hello,

That was the first thing I checked before installing the turbo.

The first two turbochargers completely burned out on the wastegate valve seat, resulting in a permanent bypass within the turbo. This also caused very low boost pressure, barely exceeding 0.6 bar of overpressure.
The pressure sensor is also working correctly; it's connected directly to the bypass line on the turbocharger, and then to the control unit with the pressure connection.

Krissi.

Hi Krissi,

I've been following your problems for quite some time now. A thought just occurred to me, and I don't recall if this has already been discussed:
Have you thoroughly checked all the connectors (ECU, MAF sensor, solenoid valve, pressure sensor, etc.)? It's possible that a contact inside one of these connectors has shifted inwards or, for some unknown reason, is bent in a way that prevents proper contact.
I once had an old 43 model 5T, and in that case, the problem was exactly at the connector of the cold start valve.

Unfortunately, I still don't have a VAG-COM, so I can't really help you further... especially when it comes to things like comparison values.

Best regards and good luck.
Wool.

Hi,
Are 2 chargers completely broken?
That's absolutely unusual!
It must be that the exhaust gas temperature is too high. Everything else about the boost pressure is irrelevant for now.
"I've already gone through 2 ESPs. I would continue troubleshooting without the chip for now. And first, I would check the return line under load for air bubbles."

hello,

@ Wool

hi, still alive, huh?

I've already checked the wiring connections, and in some cases, I've added new connector pins or run new original wires. The only other option would be to replace the entire wiring harness, but that's a huge undertaking! And you never know if it will actually solve the problem.
It's not so bad because of VAG-Com. Sharing experiences and thinking together is sometimes better than any amount of money exchanged for a VAG-Com device.

I hope we hear from each other again.
Best regards,
krissi


@christians

I'm not 100% sure what caused the first turbo to fail, but it had approximately 160,000 km on it. The second one (after about 22,000 km) failed due to two defective fuel injectors (new ones were installed!). This caused a dripping combustion process that reached the turbo. The exhaust manifold was also completely warped. The workshop strictly refused to honor the warranty or any goodwill, claiming that I supposedly tampered with it myself at the time.
The ESP units were all brand new and installed by VAG. I still haven't received a response to my question about what was supposedly wrong with them!

I've also checked the fuel line now (it's a nasty job because you end up smelling like fuel afterwards!).
Tested for pressure (1.5 bar), tested for vacuum (-800 mbar), and everything is leak-proof. No bubbles are present during operation/full load or idle. I installed a small air collection tank (a replica from the heating industry) in the line.
The fuel return lines (also known as the fuel injector return lines) are also all new.

The only thing that hasn't really been checked yet is the cat. I've read about cases where cats might have been involved, but I haven't personally experienced anything like that or heard of it happening.

I will also have another compression test done, or I might do it myself if I can find a suitable testing device. Ideally, I'd like to have both a dry and a wet compression test, each in both cold and warm conditions. Let's see if anyone is willing and able to perform these tests.
I haven't been able to find anyone who can perform a dynamic pressure test yet.


In this spirit.

Krissi.

The only thing that hasn't really been checked yet is the cat. I've read about it before that it might have been involved, but I haven't actually experienced it or heard about it happening in reality.

Well, something like that happened to a classmate recently. He brought a rabbit with him, and in the process, the ceramic casing came loose.

Best regards, WarLord.

Wasn't a new head gasket installed previously? Could it be too thin, for example, a gasket with only two holes instead of three? That might explain the melting nozzle and warped exhaust manifold. Have you also checked the camshaft?

hello,

@ T3Surfer

No, everything on the engine block and cylinder head is still original (except for the crankshaft and camshaft oil seals, which have been replaced).

The play and wear patterns on the camshaft are in very good condition due to the running-in process (do not confuse this with the camshaft problems found in the 6-cylinder engine!!! => because the camshafts have been properly broken in).

The injectors haven't melted, nor have the glow plugs, but the exhaust manifold is warped and has heat cracks. On the turbo, the sealing surface of the wastegate valve has completely burned away. The cause was two faulty injectors: one was no longer sealing properly, and the other was only producing a straight stream (instead of atomizing the fuel).



@ WarLord

The catalytic converter itself doesn't appear to be externally damaged, and there's nothing rattling inside. I've had a "crumbly cat" before in my 2.3L Audi (gasoline engine).
It was more about a clogged catalytic converter (due to oil and carbon buildup).



Okay, I've now set the box to the maximum "Early" setting. The cold start takes a bit longer than usual, and the engine sounds extremely rough; almost like a truck engine. In normal operation (with a gentle touch on the accelerator, not flooring it), it seems to produce less soot, but when you press the accelerator, it's like a dark night behind you! The power is unchanged, and I'll know the fuel consumption in 4-5 days.


I also checked the control characteristics (when the valve opens and when it closes) of the turbocharger wastegate valve and the EGR valve, and everything matches the specifications.

Next, all that remains is the temperature sensor... but I have no reference values to indicate how the components should behave in terms of temperature changes. Also, I don't have a direct comparison to a working component that I could use for reference.


Best regards,
krissi


PS: Now that it's getting colder and the auxiliary heater is sometimes running, the fuel consumption is at 13.71 liters.

=> Does anyone here have more to offer?

Hi Krissi,

The consumption is really extreme.

You wrote that you haven't checked the CAT yet.
I would definitely try that. With so much soot, the "self-cleaning" feature won't be able to cope with it, or hasn't been able to cope with it so far.
Install a replacement pipe during the troubleshooting process. This way, even if the catalytic converter is still functional, it won't continue to be affected by the problem.

Unfortunately, I haven't come up with anything new either.

Good luck and see you soon...

Wool.

hello,

I checked the cat... and there was nothing directly to complain about.

When blowing it out with compressed air, I was initially unsure , but on the inlet side, there were approximately 2-3% of residues (likely from the last turbo that was "burned out") attached. I removed the first layer, 1mm thick, and it was all clear.


Okay, the search continues... This time, I'll start with the fuel injectors and then move on to the turbo. I'm going to "borrow" some parts from somewhere and try them out.


Hi krissi

Hello,

After a somewhat longer period of inactivity on the forum, I wanted to give some feedback.

As of that date:

305,000 km and a new engine was installed four weeks ago because the old one would occasionally fail (the crankshaft main bearings 1 and 2 were completely destroyed, bearings 3 and 4 were cracked, and cylinder 5 had zero compression).

In addition to the above, the clutch was also replaced, and all sensors (oil temperature, water temperature, and pressure) were changed.

Despite restoring the original condition (without chips), a lack of performance is noticeable, coupled with a barely changed fuel consumption (maximum speed is only slightly above 190-195 km/h in real-world conditions, as measured by GPS). The fuel consumption at 95% highway driving at 150-170 km/h is approximately 11.5-12 liters.

The turbo and exhaust manifold have been replaced three times in the meantime (before the ATM; the last ones were completely burned out => photos available upon request via email).

"Boost pressure is present according to the display. I haven't yet performed any diagnostics using VAG-COM due to time constraints, but I will do so soon."

"Fuel injectors completely overhauled (new injector nozzle installed). The electric fuel pump has been replaced approximately 2 years ago, twice. However, I still suspect it's faulty due to the high fuel consumption. Unfortunately, the diagnostic readings on the VAG 1552 show all values within the VW/Audi specifications."
I will probably complain again, but I suspect I will encounter the same lack of responsiveness from Audi.

Vacuum pump replaced under warranty during engine replacement.


If there's any new information, I'll let you know!



PS: If anyone has any suggestions on how to regain control (in terms of performance and consumption), please feel free to pass them on to me!



Best,
krissi

Have you checked to see if the brake calipers are stuck?

Kristian wrote:

Despite restoring the original condition (without chips), a lack of performance is noticeable, coupled with a barely changed fuel consumption (maximum speed is only slightly above 190-195 km/h in real-world conditions, as measured by GPS). The fuel consumption at 95% highway driving at 150-170 km/h is approximately 11.5-12 liters. The turbo and exhaust manifold have been replaced three times in the meantime (before the ATM; the last ones were completely burned out => photos available upon request via email). PS: If anyone has any suggestions on how to regain control (in terms of performance and consumption), please feel free to pass them on to me!

What about the injection start regulation?

In my opinion, issues like soot formation, lack of power, high fuel consumption, and heat damage to the turbocharger can generally all be attributed to an injection timing that starts (much) too late.

While, on the other hand, an error message "Spritzbeginn Regeldifferenz" would then appear, I don't know what error amount and duration can still be tolerated without an entry .

Okay, please log this specific MWB (Material Waste Board) entry.

Hello,

Okay, so to summarize briefly:

Now that the engine has been replaced, the original condition has been restored (this is not a tuning modification!).

There is no visible soot or other smoke plumes (which is something to be happy about!).

"There are currently no visible thermal changes (beyond what is considered normal, such as a slight blue-gray discoloration on the turbo and exhaust manifold, etc.), but it's also not running at 100% continuously, and the chips are not yet installed."

According to the TDI graph, the injection start timing is set to "optimal." However, the value in control module 4, parameter 4 (ventilation control for injection start timing, N 108), should be between 4-40% according to the VAG manual, but it is usually between 57-80%. According to the VAG manual, this indicates a significantly delayed injection pump setting; the manual states: "Adjust injection pump/injection start timing!!"

But he's just really into being perfect.

In any case, I can't explain these contradictory values because they are both influenced by the same factors.

There are no error entries.


"The subjective driving experience is quite disappointing. A former colleague with an A6 with an AAT engine (115 hp) and a 6-speed conversion easily outpaces me in every situation, whether it's acceleration, mid-range power, or top speed. And let's not even talk about his fuel consumption, which ranges from 5.8 to 6.8 liters per 100 km (normal driving to very aggressive driving). I understand that this fuel consumption can't be directly applied to my A6, but realistically, a consumption of 7.5 to 8 liters per 100 km should be expected (which is what I also experienced when I first bought the car)."

The indicated injection volume does not allow for a conclusion about this enormous consumption (the displayed value of 6.8 to 7.2 mg per injection is normal, whereas the optimal range is 4-5).

Regarding boost pressure, the difference between the target and actual values doesn't show anything unusual. Initially, the actual boost pressure lags behind the target, but shortly before maximum torque, it starts to lead, eventually reaching a point of agreement.

The lambda values from the lambda sensor are all within the air excess range across the entire speed range.

I haven't yet performed any detailed analyses of the key performance indicators (KPIs), but I've done a brief, preliminary check of the most important ones. I will conduct a more thorough analysis when I have the time and opportunity (as it's important that the results are meaningful).





@ dcjf

The ease of movement and rolling resistance of the wheels and drives were checked (using a brake testing stand). Nothing unusual was found.



Best regards, Kristian.

Kristian wrote:

According to the TDI graph, the injection start timing is set to "optimal," but the only other issue is that in control module 4, value 4 (ventilation timing for injection start, N 108) should be between 4-40% according to the VAG manual, but it is usually between 57-80%. According to the VAG manual, this is a much too late setting for the injection pump; the manual states: "Adjust injection pump/injection start!!" But he's just really into being perfect. In any case, I can't explain these contradictory values because both are influenced by the same factors.

Despite this, during operation, the start of injection can be delayed due to a defect (e.g., the injection control valve is stuck, the return throttle is too large or missing...). Logging data provides clarity.

Hello Kristian!

Did you actually transfer all the sensors/transducers (speed sensor, etc.) from the old engine?

Um den Verstellweg des Kolbens der Spritzbeginnverstellung zu prüfen, brauchst Du eigentlich nur bei laufendem Motor das Ventil f. die Spritzbeginnverstellung abstecken u. beobachten (Vag-com) ob der 'früh-' Wert erreicht wird (Vollastwert lt. S(full value table)!

By the way: Is it possible to install the toothed wheel for the crankshaft sensor slightly misaligned in the AAT/AEL engine? It could potentially be a cause of incorrect fuel injection timing that cannot be detected with VCDS because the engine control unit is unaware of it, as it uses the pulses from the crankshaft sensor as a reference for the top dead center (TDC) of cylinder 'X'.

Greetings,
Andi.