Boost Curve for ALH 66kW Engine

Hey fellow mechanics,

I am looking for a boost pressure curve for a 66kW ALH engine in a Volkswagen Golf 4.

I drive a vehicle like that and I'm having problems with the boost pressure control.
When I'm driving in 4th gear at 2500 RPM and then give it full throttle, the boost pressure suddenly jumps to 1.4 bar and stays there for about 1.5 - 2 seconds. Then it drops sharply to 0.5 bar (the acceleration noticeably decreases), and only when the engine reaches over 3000 RPM after several seconds does the boost pressure slowly increase to 0.9 bar.
It's likely that something is not working correctly or is stuck with the VTG (Variable Turbine Geometry) adjustment. Since the vehicle is still under warranty, I don't want to tamper with it myself and I need a reference boost pressure curve of a correctly functioning boost pressure control system to be able to demonstrate the fault to the workshop.

It would be great if someone among you could provide me with something like that.

Regards,

Eike.

Perhaps this will help you.

http://www.ralfhandel.de/ladedruck.jpg
http://www.ralfhandel.de/ladedruck2.jpg
http://www.ralfhandel.de/ladedruck3.jpg

Skoda Octavia Estate/Wagon 1.9 TDI Automatic 66kW (ALH)


I would say it's either a stuck actuator or a faulty control valve. Focus on the actuator. You can easily try moving it manually or applying vacuum pressure to it with a large syringe.

Click on the corresponding link in the menu here as well.

CU Gremlin.

eike wrote:

When I'm driving in 4th gear at 2500 RPM, and then I give it full throttle, the boost pressure suddenly jumps to 1.4 bar and stays there for about 1.5 - 2 seconds. Then, it abruptly drops to 0.5 bar (the acceleration noticeably decreases), and only after the engine reaches over 3000 RPM after several seconds, does the boost pressure slowly increase to 0.9 bar.

Hi.

I assume you have an LDA installed, or are you doing your own measurements using VAGCOM?

For the latter, simply displaying the measured values might be sufficient. As far as I know, the test condition is full throttle from 50 km/h in 3rd gear, and at 3000 rpm, the measured values should be saved or printed.

1.4 or 0.5 bar are so far outside the normal range that the workshop (in reality) must do something about it.
What that is, shouldn't actually matter to you because of the warranty.

Hello Gremlin and Ulf,

The characteristics of the links are not bad, but the disadvantage is that no values can be read from them.
I installed a mechanical LDA with a pressure gauge (measuring range up to 1.6 bar). I simply connected the pressure hose to a cannula and inserted it through the thick rubber connector in front of the EGR/bypass valve system. I secured everything in place, and it was done. It works really well. I used a 30mm pressure gauge, which ideally fits perfectly into the plastic compartment above the radio.
I already downloaded VAG-Com as a demo version from the internet, but I haven't put it into operation yet because the adapter plug is not ready.

'On my old Golf 3, I also had an LDA (turbocharger). It also had overboost when accelerating, but the boost pressure stabilized immediately at about 0.95 bar, without dropping as much as it does on my new one.'

As I mentioned, if someone could provide me with a characteristic curve with values, that would be really helpful.

Thank you and best regards.

Eike.

PS: How can I actually insert images here?

Please.

http://www.ralfhandel.de/ladedruck2.CSV
http://www.ralfhandel.de/ladedruck3.CSV
http://www.ralfhandel.de/autobahn.CSV


CU Gremlin.