Audi TDI AEL: Starting Problems & Troubleshooting

Hi.
I know this topic has been discussed here many times before, but I couldn't find anything relevant in my search.

'I have to crank the engine for a very long time whenever it's been sitting for a while. When it finally starts, it smokes quite a lot at first. The injection timing is set early ---> according to the workshop. However, I'll have it checked again this week and get the values written down or printed out.'
What other possibilities might there be? It's quite warm outside . Or, how could I test these relatively easily and inexpensively?
Last year, new or refurbished diesel injectors were installed.
greetings

Hi,

"to stand for a long time" or "to stand for extended periods"
Is the diesel filter or its supply line leaking, causing it to slowly drain towards the fuel tank and requiring it to be bled again before starting?
You could try parking downhill and then see if it works.

Best regards from Berlin.
Olli.

'Lange stehen' means standing for a long time, either from evening until morning, or from the start of work in the morning until the end of the workday in the evening.
Unfortunately, I can't stay still for very long when going downhill.
greetings

Hi,
Then, when checking the organ, take a look at the hoses connected to and from the diesel filter, especially if they are transparent. (Ideally, someone else should start the engine). If you see a lot of air bubbles, you can assume there is air in the system. New hose clamps often work wonders. Mine had the same problem, and I replaced the standard pinch clamps with screw-type clamps, and everything was fine.
Best regards from Berlin.
Olli.

Hi,
Then, check the hoses connected to and from the diesel filter, especially if they are transparent. (Ideally, someone else should start the engine). If you see a lot of air bubbles, it's likely there's air in the system. New hose clamps often work wonders. Mine had the same problem, and I replaced the standard pinch clamps with screw-type clamps, and everything was fine.
Best regards from Berlin.
Olli

Hi.
Okay, finally found a second man or woman . Air bubbles have appeared in the transparent tube. What possibilities are there to limit the 'air intake'? Could it really only be due to the hoses, or are there other causes?
Okay, so if it's running, I turn it off and then start it again, and it starts up. It seems like that's the apparent cause.
greetings

Okay, then it's a good idea to check all hose connections, including the fuel lines and fuel filter, all the way to the tank.

Hello.
I just had the values read out: the first value is 48, and the second value is 28. It seems to be in the lowest range, which suggests a problem is being detected.
However, the error log indicated a 'fluctuating signal' from the needle lift sensor.
I'm working on the connections. It will probably be something that happens over the weekend. I hope to finally pinpoint or solve the problem by then.
Greetings.

Hey, any progress on your issue? Did you replace the hoses/clamps? Did it get any better?

Hi, has anything changed with your problem? Have you replaced the hoses/clamps, has it gotten any better?
Hello.
I was on vacation . Unfortunately, no . I think it's getting worse. So, I checked all the hoses/clamps and either inspected them or replaced them.

The problem persists: It takes a long time for the engine to start, and it runs roughly afterwards. If I turn it off as soon as it starts running smoothly and then restart it a few minutes later, the engine starts misfiring again, for some reason. However, if I drive a few kilometers, everything works fine.
Does anyone have any other suggestions? It's always embarrassing when the car doesn't start for what seems like 'hours.'
Greetings.

Hello.

The problem is still there and it's annoying . So, I replaced the diesel filter, and I even installed a check valve between the filter line and the pump, but it didn't solve anything. My workshop foreman still thinks it's the pump itself, hmm... Before I install a new one for a lot of money or have it disassembled, what else can I do?

By the way, does anyone know about batteries from the company Optima, specifically the red and yellow ones?

Greetings.

Have you managed to remove those air bubbles from the diesel line yet? If not, start there. For testing, add more clear sections of tubing (before/after the diesel filter, before and after the return line, near the tank, etc.). Then you can see from which point the air bubbles increase, and you can pinpoint the leak.

Without knowing the exact source of the air itself, no one here will be able to help you.

Regards,
Guste.

Have you at least managed to remove the air bubbles in the diesel line yet? If not, start there. For testing, insert more clear hoses (before/after the diesel filter, and before and after the return line, near the tank, etc.). Then you can see from which point the air bubbles increase, and you can find the leak in that way.

Without knowing the exact source of the air itself, no one here will be able to help you.

Regards,
Guste.

Return line?? Hmm, I just thought the supply line was important. Then I'll have a little fun.

greetings

Honk wrote:

Return pipe?? Hmm, I just thought the supply pipe was important.

Wrong guess .

When the engine is cold, the return line is short-circuited with the supply line (using a device often called a "Knackfrosch" on the diesel filter) to allow the diesel fuel in the small circuit to warm up faster near the pump. Try searching online; you'll find a lot of information on this topic (keywords: "Knackfrosch," "KGR," "diesel circuit," etc.).

SUper, now I'm stranded . It suddenly stopped working, and there's air in the line between the filter and the ESP . I was planning to replace or inspect all the seals, etc., on the return line this weekend. Great. I've been having the starting problem for a while now, and the question is, why did it shut off while I was driving ? Last weekend, I 'only' installed the filter and a check valve between the filter and the ESP. The filter was an aftermarket part, hmmm.
Can someone tell me what torque (in Nm) I should use to tighten the hollow screw on the filter?
What do you think, is the 'dirt' a filter or just random noise?

Greetings.
Bernd.

Hello.
The issue with the filter is resolved; it was my mistake . However, the starting problem hasn't changed . And no more air bubbles are coming through the hose.

There must be another possible reason for this, right?!!

Greetings.

Hi! I suspect that the distributor body of your injection pump has already failed. Unfortunately, it's a wear part. The starting speed is significantly lower than the idle speed. This means that the leakage between the pump cylinder and the plunger is greater. This could mean that the starting amount is not sufficient to start the engine. The AEL engine has definitely exceeded 200,000 km.

Best regards, Rudi.