AU Nozzle Experience: Big Nozzles Explained

Hello everyone.

Now that it seems certain that larger nozzles actually allow "a bit" more diesel into the cylinders, I wonder what happens with the emissions test (AU) as a result.

Even if the soot level is still acceptable, the excess fuel will increase the engine speed – to the point where the software will prescribe a correspondingly lower injection quantity, and the injection quantity and engine losses will balance each other out again.

So, who has relevant experience, or who would dare to try the AU test themselves (with the engine properly warmed up, then giving it full throttle for about 3 seconds while stationary until the RPM stops increasing)?

Of course, this statement is only meaningful if the EDC is otherwise in its original condition, i.e., in particular, if no chip tuning has been performed for the larger injectors.
So, we have 66kW motors with 81kW injectors, KW tuning injectors, or even the 216 um injectors from the 111kW T4 engine. Or 81kW motors with the 216 um injectors. Or other "secret" combinations .

Note: For the AFN engine, the maximum permissible engine speed for emissions testing is 5200 rpm. Those who achieve better results with larger injectors probably don't even need to go for an emissions test in the first place, as far as I know.
As a possible solution, I could try a VAGCOM adaptation via channel 1 (entering lower values), and if that's not enough, adjust the pump to be leaner (by shifting the control lever).

I will probably be offline until Easter. Nevertheless, I am looking forward to every reply - so until then...

Hello,

I have always assumed that the engine control unit monitors the engine's speed limit, and that the fuel injection amount is reduced when the speed limit is reached. Therefore, it shouldn't matter whether you have large or normal injectors.

Best regards,
Christian.

Hi Ulf.

"I have a question. Do you know for sure whether the injectors from the AFN engine will fit into the AGR engine? I'm not asking if they physically fit, I know they do. I'm asking if the spray pattern is the same. I'm about to buy some AFN injectors, and I really don't want to end up with melted pistons."

Best regards.

Tagessuppe wrote:

Do you now definitely know if the injectors from the AFN engine fit into the AGR engine? I mean, not whether they physically fit, because I know that, but whether the spray pattern is the same. I'm about to buy AFN injectors and I really don't want to end up with melted pistons.

Hi.

The most official information I have on that topic is the presentation of the AFN in the MTZ.
The text essentially states that the combustion chamber geometry was adopted unchanged from the 66 kW engine (originally 1Z / AHU).
However, the piston alloy is designed for higher temperatures.

The spray pattern of the AFN nozzles should therefore be compatible with the 1Z / AHU engines without any modifications.
Unfortunately, I don't know if the same applies to the AGR .