Fixed Issue, New Problem Arises

Hi everyone!
I replaced the turbocharger boost control valve because the old one was rattling, and now it's working fine! But I think the AFN engine feels a bit sluggish from 3500 RPM until it reaches the 'rev limiter.' The EGR is deactivated, and the injectors have 251,000 km on them. The maximum speed I've reached recently is 170 km/h, and the oil consumption is about 1 liter per 10,000 km. Does anyone have any other suggestions? The VTG (variable turbine geometry) is working properly and reaches high boost very quickly below 3500 RPM!
Best regards,
Holger

Hi.

Your car seems to be one of those cases that make me think an LDA (Lean Deposit Additive) should be a standard feature for every TDI .

So, either build one (at least temporarily), or do some data logging with VAGCOM while driving at full throttle from approximately 2500 to 4000 rpm.

Then you can see further...

atzleh wrote:

...Nozzles with 251,000 km on them...

... they probably wouldn't produce a good spray pattern anymore...

Check the boost pressure while driving. If everything seems normal there, I would consider having a nozzle test performed.

Hi, thanks for the tips. It might be related to the compression, but if that were the case, wouldn't the problem be more noticeable 'down low'? Or maybe the turbocharger isn't building up boost quickly enough in the upper RPM range, as it takes a long time to shut off. - Holger

Ulf, Bertil, and I are telling you to check the boost pressure.

Okay, I'll do that for you...

Hi.

@Holger
In my opinion, poor compression is most noticeable during startup and at lower engine speeds.

@Bertill
Can worn nozzles lead to a situation where only power is lacking :in the higher RPM range?

Okay, I'll do it! Where do I connect the hose, and where can I get the pressure gauge (display)? I'm very inexperienced in this area. Thanks in advance, Holger.

A pressure gauge suitable for use with an acetylene welding apparatus is the Azetylen pressure regulator.

ulf wrote:

@Bertill Can worn nozzles cause a situation where onlypower is lacking

in the higher RPM range}?

Why not?
If the spray pattern is poor, "large" droplets can form, which, especially at high speeds, can hinder good and clean (fast) combustion.
Imagine this: At high RPMs, the VP (presumably a fuel injector) is known to deliver the highest pressures, and now the injector is spraying fuel, but due to a poor spray pattern (bad atomization), some of the diesel is hitting the wall of the combustion chamber. This fuel isn't being used for combustion, and therefore, you're losing power.
However, the engine should also exhibit other symptoms (knocking, misfiring, poor cold start, smoke, etc.).

With over 250,000 km on the engine, the injectors are likely not in the best condition anymore.
I suspect the problem lies more in the turbocharger boost pressure control system.

Peter 2 wrote:

A pressure gauge suitable for use with an acetylene welding machine is the Azetylen pressure regulator.

If that's still not something you can find, check the heating and plumbing section of the hardware store.
It goes up to 4 bar, but it doesn't really matter.

atzleh wrote:

Okay, I will do it! Where do I connect the hose, and where can I get the pressure gauge (display)? I am very ignorant in this area. Thanks in advance, Holger

Of course, there are also "genuine" LDAs (Load Detection Amplifiers) available in the accessory trade. For the AFN (presumably a specific device or application), a measuring range of 1.5 bar is sufficient.

The pressure can be conveniently accessed by connecting a T-piece to the hose leading to the intake manifold, then connecting it to the engine control unit.