Injection Start Control, Difference Regulation. MKB: AKN Automatic

Hello.

'My father's car has been experiencing a problem since today. It's an Audi A6 Avant quattro with the AKN V6 TDI engine. Until yesterday, when it was parked in the garage, the engine ran without any noticeable issues. This morning, he tried to start the car, but it wouldn't turn over. After several attempts, the engine finally started, but with a lot of smoke and very rough idling. He still drove it, covering about 2 km, before the engine stalled. He restarted it, and it ran again, but still very roughly, with loud knocking and clattering noises. I then read the error codes, and one code appeared: 00550, 'Injection timing control,' with the fault code 17-00, 'Control difference.' This error reappears immediately after clearing it.'
Okay, the timing belt looks good and is properly tensioned, and the fuel tank wasn't run empty. What's strange is that it happened so suddenly.
Sure, I suspect the fuel injection pump, but how can I check it more precisely? I can see air bubbles in the fuel hose leading to the ESP (Electronic Stability Program). Is that normal? The filter was replaced during the last inspection (15,000 km ago).
Can anyone help? I've also read several times about lifter arms that simply fall off! I would be very grateful for any tips.

Regards,
Frank.

It's likely that a seal in the diesel supply line has failed. Please check if everything is okay with the distributor (often called a "knackfrosch") and the diesel filter. If necessary, simply replace the hoses and clamps there.

Thank you for the quick response. Wow, that sounds very simple and cost-effective. It's almost too good to be true. I'll continue troubleshooting tomorrow; I also suspect the fuel pump might have failed.

Regards,
Frank.

Check if you hear a hissing sound when you open the fuel cap after a longer drive.
Perhaps the ventilation in the lid is faulty. If the pump then cannot generate enough fuel pressure, it could also lead to hydraulic pressure problems with the fuel injector adjuster.

The problem was actually with our AKN. A small cause, a big effect.

frank_24 wrote:

Thank you for the quick response. Man, that would be very simple and cost-effective. It's almost too good to be true. Tomorrow I will continue troubleshooting; I also suspect that the fuel pump may have failed. Regards, Frank

.
For the tenth time: The vehicle does not have a pre-lift pump; the pump in the tank only fills the surge chamber. When the tank is full, its function becomes irrelevant.

Okay, so yesterday I spent a few more hours working on the engine, but with no result. According to VAG-COM, the injection timing is fluctuating wildly between 2° before and 2° after TDC, sometimes even more. This fluctuation can't be right, can it? Also, there's no more air in the fuel line, so everything seems okay there.
Right when starting, you can hear a hard knocking sound that's best described as 'clunk, clunk, clunk.' Once the engine is running, you don't hear it anymore. However, even then, the engine runs roughly and unevenly.

Tomorrow, the car is going to Audi so they can take a look at it.

Have a nice day.

Regards,
Frank.

Hello again,

I've done some research in various forums. Could worn camshafts and consequently detached lifters be the cause of the problem? After all, the engine now has 265,000 km (approximately 165,000 miles) on it and has never been opened before. It might also explain the loud 'clunking' sound.

Regards,
Frank.

Hello again,

I've done some research in various forums. Could worn camshafts and consequently detached lifters be the cause of the problem? After all, the engine now has 265,000 km on it and has never been opened before. It might also explain the loud 'clunking' sound.

Regards,
Frank.


Sure. It's to the point where the rocker arms are falling into the head. A visual inspection can help. It's best to remove the valve covers .

Hello,

The car was in the workshop today and is running again. It turned out that the timing belt for the fuel injection pump was defective. Almost half of the teeth were missing. Of course, an engine can't run properly like that. Fortunately, nothing more serious happened. From the top, the belt looked brand new. That's how you can be deceived.

Regards,
Frank.

Thank you for the feedback!

Do you know how old the belt was and what the Big One looked like?

Regards,
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It can also be used as a verb, meaning "to gust."

Hello,

Okay, the belts have probably been on for over 140,000 km. So, it's more likely due to driver negligence and inadequate maintenance. The larger belt hasn't been replaced yet because it needs to be checked first to see if anything else might be broken. If so, that will also be replaced. The smaller belt is relatively easy to replace without having to remove the front of the car.

Regards,
Frank.