VCDS and OBD diagnostic device in the On-Board Diagnostics Shop
Diesel, Engine Technology and Vehicle Technology. Repair, Maintenance and Diagnostics (OBD).

AAT Injection Start Regulation

 
New Topic Reply 🔗 ⭐ 🖨 Dieselschrauber - Index » Diesel Engine Technology
Author Message
Andi aus dem Ösiland
Guest




 


Free account, no CAN development support

Post23-02-2004, 16:35    Subject: AAT Injection Start Regulation Quote

Hello!

Okay, here's a silly question: Is there any operating condition where the injection timing is later than it is at idle? I think the injection quantity will never be lower than at idle, or will it? (Except maybe with cylinder deactivation, but in that case, the injection timing doesn't really matter anyway, does it?)

Here's the translation:

'The reason for my question is that my static injection start timing is adjusted so that, at idle, the control system doesn't quite have to fully adjust to achieve the injection start timing desired by the engine control unit (ECU) at low load! It should actually be okay, right?'

I've read a lot of articles about pump settings, but they don't mention anything about idle values.

Greetings.
Andi.


Translated on 08-10-2026, 11:50.
Back to top
christians
Profi-Schrauber
Profi-Schrauber


Joined: 09/05/2002
Posts: 2105
Karma: +17 / -0   Thank you, like it!
Location: Sauerland

Premium Support

Post23-02-2004, 17:36    Subject: AAT Injection Start Regulation Quote

Hi,
It never idles lower than it should, or at least it has never noticeably tried to. Under load, it tends to advance the timing slightly, around 9 volts at the fuel injection control.
With an injection start timing that was slightly delayed even at idle, my AAT (presumably an engine type) was not starting well. However, it's also possible that my fuel pump is not working at 100% efficiency.
Gruß Christian
A6 BPP, Ex-A6 AKN (Gurke), Ex-Audi100 92 AAT (5Zyl.)


Translated on 08-10-2026, 11:52.
Back to top Profile PM
dieselmartin
Profi-Schrauber
Profi-Schrauber
Avatar-dieselmartin

Joined: 03/13/2003
Posts: 10121
Karma: +29 / -0   Thank you, like it!
Location: in der Werkstatt
2007 Volkswagen Passat
Premium Support

Post23-02-2004, 18:57    Subject: AAT Injection Start Regulation Quote

Um hm, a quick question:

"-3.1 degrees" in VAGCOM means 3.1 degrees AFTER TDC (Top Dead Center), which implies a maximum late ignition timing.

Because under load, it reaches 9 degrees.

I had previously asked about the somewhat inaccurate start time of my first injection, and I just realized that I obviously mixed up the early and late times.
/viewtopic.php?t=5071&highlight=



Thank you for the clarification.
m;


Translated on 08-10-2026, 11:53.
Back to top Profile PM Garage
Andi aus dem Ösiland
Guest




 


Free account, no CAN development support

Post24-02-2004, 12:59    Subject: AAT Injection Start Regulation Quote

While I can't provide definitive answers since I'm not familiar with VAG-COM, a multimeter and oscilloscope can reveal almost everything!

If it goes to '9' under load, then positive numbers should indicate an earlier injection start (which, for me personally, seems illogical icon_confused.gif).

Given your uncertainty, I would suggest connecting a VAG-COM diagnostic tool, checking the injection timing, and then disconnecting the solenoid valve for injection timing control. The value displayed then will represent an earlier injection timing (and the engine knocking should also be audible!).


Translated on 08-10-2026, 11:54.
Back to top
New Topic Reply 🔗 ⭐ 🖨 Dieselschrauber - Index » Diesel Engine Technology
Similar articles and topics
Topic Forum
No new posts EDS Regulation flawed! Found the mistake! Faults & Documentation (Audi, VW, Seat/Cupra, Skoda)
No new posts Passat AVG: Injection Start Control Error 17656 On-Board Diagnostics (OBD)
No new posts ALH Load Disconnect Control System On-Board Diagnostics (OBD)
No new posts Bi-Turbo Regelung Upload
No new posts How can the VTG regulation be verified? Diesel Engine Technology
Jump to:  
You cannot post new topics in this forum.