Fuel injectors V6 2.5 TDI

Hello.

I've been working with a friend for a while now, trying to diagnose starting problems with a V6 AKE engine. Everything seems to be in order, including the fuel injection timing and there's no sign of air leaks.
"In the spring, he replaced the injectors. Since he still had the old ones, I took a look at the numbers and noticed that the last letter doesn't match the original injectors that were installed. Apparently, they were supposed to be for a "BAU" engine. I strongly suspect that the starting problems are related to this. These problems supposedly started after the replacement. Can anyone give me some advice on whether this is likely to be the cause?"

In principle, no. If they need to open slightly later due to potential other pressure requirements, it would help to adjust the pump to start a little earlier, even if it then runs idle or... The control system is operating at partial load and is reaching its limit.

It's best to post the part numbers at this point. Then we can say more.

Hello,

Okay, so originally the 059 130 201 F catalytic converters were installed... and I inquired whether they are compliant with Euro 3 emissions standards.
The new numbers are 059 130 201 G......... and they are EURO 4 compliant!

Okay, so the difference is between EURO 3 and EURO 4 standards. Could that be causing the starting problems, because perhaps the software for the pump isn't calibrated for these injectors?
Please help.
Sincerely,

As I mentioned before, the differences aren't significant, and Rainer might know more about the specific details. That doesn't make the cabbage fat.
The problem likely lies elsewhere. In the worst-case scenario, the pump may have been damaged during the bleeding process.

There are significant differences regarding the size of the holes. It's possible that when it starts, just a little less goes in.
What does the TDI timing checker say?

Best regards, Rainer.

Can't you increase the starting values using VAG-COM for testing purposes?

Hello,

The TDI timing is almost exactly aligned with the blue target line. I've already checked this.
I still don't know the reason for the starting problem. The only thing I've tried, and which seemed to help a little, was disconnecting everything and reconnecting it, and then skipping the basic setting with the 2° BTDC. It starts a bit better now when it's cold, but not dramatically. Maybe you know something more about it?

Okay, why don't you do a test run with Block 4? As long as you're not approaching the late injection point, you can definitely adjust the timing towards earlier. Even if you're easily able to reach the late injection point, not much will happen because that only occurs under extreme partial load conditions. At some point, an error should be recorded.