Problem: Cylinder failure in AKE

(Title changed / Ulf)

Hello everyone!

I have already posted about my problem, but I still need to bother you. I can't seem to find the solution to my problem.
I have an A6 Avant Quattro V6 TDI 180 hp AKE, manufactured in 4/2000, with 165,000 km on the odometer.

The car has been doing the following for (!) one year:

Once the engine is hot and I'm driving faster than about 160 km/h, it feels like the engine is only running on a few cylinders. About a year ago, I could at least drive at 200 km/h and faster. But the problem only occurred after a long, full-throttle run. Now the time intervals are getting shorter, and this is also occurring with much shorter travel times.
The engine initially starts up easily, but then gradually begins to emit a blue smoke, eventually cutting out. (I have only driven long distances on the highway, reaching 165,000 miles) After this, you need to let the engine run for a while before it starts to take fuel properly again.
I have already had x trips with VAG COM. The only thing that is noticeable is that the air mass sensor starts to 'jitter, vibrate' extremely when it happens. The boost pressure is perfect. No error codes. Almost no oil consumption.

I have exchanged the following so far:

LMM (Values not achieved)
all filters renewed
Temperature control unit on the diesel filter replaced (apparently a problem)
all nozzles (needle hub actuators were in fault memory, now OK)
Replace the incandescent bulbs (two were missing from the set)
'Here, camshaft inspection (which should be a problem, but was fine)'
VTG operates flawlessly.
Pump replaced (some VAG people said!)
AGR Valve Disconnected (with Sheet Metal)
Engine compartment ventilation renewed (was spotless)
Pumps in the tank checked (drawing verschandeln 6.0 A)
Probable replacement of control unit
Hoses between LMM and Turbo replaced (tip from Ingolstadt)

Audi says: We haven't experienced this before.

Do you have any other suggestions ?????? I'm open to any advice !!!! I'm completely at the end. It's no longer fun to drive the car at all. The car was in perfect condition until a year ago, and it used to run like a clock.

Best regards,
Knubbi

Do you mean that --Pumpe-- replaces the fuel injection pump?

What does the error log say now, after you've performed all the changes you described?

Have you ever checked the fuel pressure at the fuel pump when the error just occurred?

...with pump, I mean replace my fuel injector pump, yes.

The error memory is always empty.

Measure the pressure at the pump? What pressure? At the fuel injection pump? Where should I measure it and how big should it be?

The only thing that's noticeable is that the air mass starts to 'jitter' or 'tremble' violently when it happens. The boost pressure is like a single unit.

The boost pressure should not be as high as one, as the speed and other factors continuously influence the conditions.
I would like to review these measurement and regulatory elements.

I am a 2.8 C4 driver, and that's my only opinion.

@brunhilde

What do you think?

@knubbi

what do you think, what pressure does the ESP generate? 1 bar, 10 bar, 500 bar?

Although I am dependent on gasoline, the boost pressure is a measure of the air pressure between the turbocharger and the intake valves, and therefore has nothing to do with 'how much pressure the ESP generates?' because, as far as I know, 'ESP' is the fuel injection pump, which should be related to diesel and its injection pressure to the nozzles.

@brunhilde

@joergs:

how should I measure the fuel injection pressure? And especially on all 6 cylinders? Do you have an idea?

I also had another thought:

There is a contact in the fuel pump in the tank labeled 'Empty Tank', which instructs the control unit to shut down a cylinder bank to signal to the driver -> FILL UP, otherwise there is a problem!

Are there any other 'engine protection features' that interfere with cylinder operation? Perhaps, for example, gear protection? Does anyone know how to measure this type of procedure?????

so, the injection pressure should be around 1200 bar at the pump under full load.

if the nozzles and pump have been replaced, I don't think there's any defect.

with fuel pressure, I meant to check the pre-feed pressure at the ESP, i.e. the pressure that the pre-feeding pumps bring.

Performance loss and blue smoke at high load indicates fuel shortage...

Sometimes, this can actually be an intervention by the safety circuit for an empty tank. However, this can be relatively easily checked by simply setting the relevant switch to manual operation...

I would like to remove and inspect the tank pumps, and if necessary, verschandeln them. It is possible that one of the suction pumps is simply worn out.
also, the pipes to be blown out.

As with the VP37, the VP44 also has a wing-shaped pump that naturally delivers more fuel at higher speeds. This may then lead to problems in the fuel supply...

by the way:
If a cylinder bank fails or individual cylinders fail, the LMM value will naturally fluctuate, as there will be a massive loss of drive power for the turbocharger...

See you, Gremlin

@Gremlin

Thanks for your input!

I will now think about how I can measure the pressure before the filter. I estimate that the pressure will not be more than one or two bars. Disassembling the tank is probably an unpleasant task.

I measured the pump flow according to Elsa, but only when the pump was stationary. And it was exactly 6.0 A, as specified. (No mention of pressure)

Then I'll take a look further.

That must be found.

Question: If there is a fuel shortage, why is the peak start control not listed as an error in the fault memory?
I'm already starting to ignore the logic and just substitute.

Best regards,
Knubbi

Are you sure that a cylinder bank should be shut down in case of fuel shortage?

As far as I know, in the case of an URGENT fuel shortage (Warning 3), the engine completely shuts down to prevent air from entering the ESP and damaging it.

IF this happens, there will also be an error entry in the control unit (empty tank).

So, if the fuel level sensor is the culprit and the control unit is shutting off accordingly, there should at least be a corresponding entry in the fault memory.

What about air in fuel lines? That could be the case; a small leak that initially doesn't cause any problems, but which gradually increases over a year and eventually sucks in more and more air, becoming a bigger and bigger problem.
Subsequently, the ESP is receiving too little diesel, especially when the required injection volume is high, and the engine starts to stutter.

For me, this sounds logical.

Stefan.

Hello Stefan!

Apparently, the 'Tank empty' switch is activated before the actual fuel level reaches 'empty'. Subsequently, a bank will be shut down.

The thing with the air is just a bit dumb, because at 160 km/h, I can't see the line in the engine compartment.

Greetings

Knubbi

knubbi wrote:

The thing with the air is just a bit dumb, because at 160 km/h, I can't see the line in the engine compartment.

It works: I once installed a piece of clear hose directly into the return air duct and then ran it with a loop all the way to the windshield.

Hello thinkers!

My adventure with my A6 V6 TDI continues:

I managed to disrupt the fuel supply yesterday. New booster pump installed.

- The error still persists -

I'm really at the end. My last hope is that I can open my valve covers again and take a close look at the camshafts. Meanwhile, the engine replacement has also been a while ago.

How does NW wear affect the driving experience? Is it just a loss of performance?

Otherwise, does anyone else have any ideas???


SEUFZ!

Greetings

Knubbi

(This was probably my last TDI)

Hi,
have you already provided hints?
- Cylinder shutdown. You should find out where the contact is located. If it was replaced along with the pre-feeding pump, it will be missing. However, the connection to the control unit with its connections remains.
-Heat: Are there any heat bridges that shouldn't be there? For example, the exhaust pipe routing or something similar. Maybe also a test drive without all the body panels and under-the-engine components.
-All other cable connections, such as NBF-EDC etc.
-Power supply: Does the alternator actually work perfectly, or does it damage the on-board network under certain conditions? I recently fixed a major issue with an old Opel by replacing the regulator.