Intermittent power loss

Hello,

'I'm having a problem with my TDI, specifically the AFN engine. Sometimes it has full power, for example, when accelerating in 2nd gear. However, after shifting into 3rd gear, the power drops significantly. It feels like losing 20-30 horsepower. Then, the power remains at this low level. Sometimes, after driving for a longer period, the power returns, but it also disappears again. After the problem occurred, I drove to my former workplace (a VAG dealership) and let the engine run while performing a diagnostic scan to try and identify any intermittent errors. Unfortunately, it was unsuccessful; there were no error codes.' Any potential leaks can be virtually ruled out; I've already checked.
I know this could be about a thousand different things, but maybe someone here has encountered a similar problem before. I'm getting a diagnostic tool on Tuesday, but until then, I won't have access to one.


I would appreciate it if someone could respond. It seems like new users aren't exactly welcome here.


Best regards, Dr. Braun.


P.S. I've also read some specialized articles...

Hello,

As always in such cases: Calibration run (see technical article => target values).

Okay, I've searched the forum again and found something interesting: the variable geometry turbocharger often gets stuck on AFN engines. Are there any new findings or solutions to this problem now? Perhaps this is also the problem I'm experiencing.

Best regards, Dr. Braun.

Under "Tips and Tricks," you'll find the tried-and-true remedy:

/viewtopic.php?t=3004&highlight=stuck+vtg


(... for risks and side effects, ask your local mechanic)

Okay, so I checked the dispenser and the rod today, and it's working perfectly. Just to be sure, I tried the whole process about 50 times, and it didn't jam even once. So, is it actually due to something else? That's a shame. And unfortunately, I haven't gotten my laptop set up yet to use VAGCOM, which severely limits my ability to troubleshoot the problem.

It's probably the solenoid valve that's broken. Try holding it upside down. It shouldn't make any clicking sounds.

It would be best to use something else next time.

Hello,

What was initially a temporary issue has now become a persistent performance problem. I finally got around to using VAGCOM today and got the following readings:

Air mass at idle ~ 450 mg/stroke.
max. Air mass during acceleration: ~920 mg/stroke.

Are they okay?

Regarding boost pressure, things are different. When accelerating from approximately 1500 RPM, the target value rises to around 1950 mbar at approximately 2000 RPM and remains there. However, the actual boost pressure increases very slowly, only reaching the target value at around 4000 RPM. The difference between the target and actual values can temporarily reach 650 mbar. There can be no performance, and the driving pleasure is like that of the SDI .

'The hoses are all leak-free, and the VTG adjustment is working smoothly, so I should finally check the VTG control valve. But how is the best way to do it, and how can I be sure? Should I simply swap the connectors and hoses from the EGR and VTG valves?' Does VTG have a blue connector?

Sure, here's the translation:

'Best regards, Dr. B.'

'I replaced the solenoid valve today and noticed an improvement in performance. According to the VAGCOM readings, the boost pressure now builds up a bit faster. However, I only reach about 1.5-1.6 bar at around 2000 RPM, and it's not until around 3500-4000 RPM that I reach 1.85-1.95 bar.' I checked the hydraulic hoses, and I couldn't find any leaks. The loader doesn't have any play and isn't leaking any oil.
What I noticed tonight is that the engine runs much, much better when it's cold. Unfortunately, I didn't have a VAGCOM scanner with me to display the long-term fuel trim (LTFT). What could be the problem? I've read all the articles and used the search function, but unfortunately, I'm still no clearer.


Best regards, Dr. B.

Hello Dr. B:

Have you ever checked the LLK (low-loss coupling) and pressure hoses for leaks? It's not that the turbocharger isn't working hard, but excessive leakage prevents the pressure build-up!

Regards,
Alex.

'And how should I best check them? Unfortunately, I don't have a device for pressure testing or anything like that. I couldn't find any leaks in any of the hoses while the engine was running. So, what's the best way to check for leaks?'

Best regards, Dr. B.

Hi,

Leaks in the hoses and hydraulic lines manifest as oil seepage. Of course, the vacuum lines between the charge air cooler (intercooler) and the pressure sensor on the turbocharger can also leak, but you can simply apply suction to check them. The taste should, at the very least, not be a problem for smokers .

Okay, I found the problem. As I mentioned before, I replaced the solenoid valve, and just to be safe, I also replaced the diesel filter. The filter was regularly changed, and biodiesel was never used, but it turned out to be the cause of the problem. Now, according to VAGCOM, all the values are back to normal, and the 110 horsepower Ibiza is running properly again.

Sure, here's the translation:

'Best regards, Dr. B.'

I would appreciate it if someone could respond; it seems like new people aren't exactly welcome here.

Hello,

I haven't read through all the replies in the thread, but everyone...
Anyone who is willing to put in even a little effort to solve problems and shows a genuine interest in the topic is welcome. Please don't give me texts like that!