Help, I'm desperate! My Audi A4 won't start. (Weblog Flor)

Last edited on 17-08-2016, 21:01, edited 2 times in total.

Dear community,
Hello, my name is Flo, I'm 30 years old, and I'm from Burgenland, a sunny region.
"I've been reading here more frequently over the past 2 months because I'm having problems with my car. I enjoy tinkering with cars myself, but sometimes I run out of ideas, so I signed up to connect with like-minded people."

I'm sorry for barging in like this, but I'm new here and I'm not really sure where to go or what to do. I could really use some help!

I drive an Audi A4 Avant 2.0 TDI B7, manufactured in 2005; the engine code is BPW.
For about a month now, I've been troubleshooting a problem with my car, but I haven't made any progress. Initially, the car started very poorly, requiring at least three attempts, each lasting about 20 seconds. However, once it started, it ran well (normally). If I turned it off and started it again within the next 3-4 hours, it would start immediately. But if it sat overnight, I would have the same problem the next day: it wouldn't start right away, and I would have to crank it for a long time.
"After that, my mechanic installed a check valve in the fuel line before the tandem pump and another one after the tandem pump, and told me to see if it would improve.

Unfortunately, that wasn't the case; I had to take it back to the workshop after a week. The mechanic said there was a fuel pump relay error in the diagnostic system, which he replaced. I got in, excited to drive home, but it didn't start, not even after trying to start it for the usual 3 x 20 seconds. What's very suspicious is that when I turn the ignition on, and it checks the individual systems, the lights go out in sequence (the instrument cluster says everything is okay) except for the check engine light, which only goes out once the engine is running. When I try to start it further..." Turning the key to start the engine, the glow plug light flashes on and off almost in sync with the engine, but the car doesn't start.
No errors found in the error memory.
The incandescent lamp lights up as usual when turned on and then turns off. But why does it keep turning on and off during the starting process?
Please help urgently.

Best,
Flo

24-08-2016, 12:33 Subject: Help, I'm desperate! My Audi A4 won't start.

The community section is intended for introductions, vehicle descriptions, etc.
For questions, please use the regular forum sections. Therefore, please repost your question there.

The intermittent pre-glow check could be an indication of a reboot of the engine control unit (ECU). Possible causes include issues with the power supply or the ECU itself. That could also be the reason for the absence of error codes in the error memory.

Does the diagnostic connection remain stable even during a startup process (e.g., to monitor engine speed)? If so: what speed is reached during startup?
Does diesel come from the return line?

Greetings.
Guste.