Turbo Problems: Solutions & Troubleshooting

I'm new here, and I have to say, the entrance test was quite challenging... but now I'm in, and I can finally share my thoughts.

First, I've already searched through almost everything here, but I don't think my [item] is here.

A4 Avant, manufactured in 04/1996, engine code AFN, 1.9 TDI, 81 kW, 97,000 km, AGR valve closed.

My turbo doesn't kick in until around 3100 RPM, but then it does so dramatically. On the way to that point, the boost pressure remains constant (according to VAG1551).

I've already checked the vacuum hoses, and they seem to be airtight. The VTG adjustment seems to be working correctly, as far as I can tell.

The mechanic at VW said today that it's a turbocharger issue, but I'm having a hard time believing that, because it should be working fully at 3000 RPM.

ps: I had the intake manifold pressure/control differential values cleared again (as I always do when I'm working on a VAG vehicle).

I hope you can help me with this.

Sure, here's the translation:

'Thank you in advance.'

andy

Hello Andy,

Quote:

ps: I had the intake manifold pressure/control differential values cleared again (as I always do when I'm working on a VAG vehicle).

Does that mean this is a permanent error?

andyy wrote:

My turbo

doesn't engage until approximately 3100 RPM, but then it kicks in strongly. On the way to that point, the boost pressure is always constant (according to VAG1551). }

Hi Andy,

I assume that "constant" here means 1 bar absolute pressure, which is equivalent to zero boost pressure?

The symptoms remind me somewhat of my previous attempts with a VTG (Variable Turbine Geometry) setting that was too long. Eventually, at full throttle, noticeable pressure would build up, but only in the area around 3000 rpm.

I initially suspect that the VTG (Variable Transmission Gear) is not coming out of its resting position, or is doing so very little.

Test: Observe the VTG (Variable Turbine Geometry) and start the engine. Immediately after the engine starts, the rod must be pushed into the membrane chamber by approximately 1 cm.
If that's the case, then the charger is probably broken. (--> Remove the intake pipe and manually turn the turbine to see if it's grinding or if it spins freely.)

If the VTG (Variable Turbine Geometry) is not moving, check everything there (e.g., injector test, solenoid valve...).

Yesterday, I had a breakthrough. With the engine running, I removed the vacuum hose from the valve. The valve travel (VTG) moved down about 1/2 cm. When I put the hose back on, the VTG moved back up 1/2 cm. I then used a screwdriver to gently pry on the VTG, and I saw that the rod moved another approximately 1/2 cm further into the valve body!

'Then I used the vacuum pump on the can, but the pressure gauge only went up to the first mark. If you help it along, it goes all the way up.'

If I do this 100 times... will it get better?
I read about a larger can in a post. Would that help? I think it has more power, if I remember correctly.

Hello andyy,

Having looked at several 110PS TDI engines, I believe the issue isn't so much the VTG mechanism itself, but rather the vacuum pump used to control it.
It can also get stuck or seize. Of course, the cartridge itself is much cheaper and easier to replace than the entire turbocharger.
My tip for you: Loosen the two M10 mounting screws on the vacuum sensor at the bracket on the loader.
If the VTG adjustment lever and the associated pressure sensor can be moved very easily and smoothly, without any resistance, then it is highly likely that only the vacuum sensor is defective.

Best regards, Rainer.

Thanks for the tip... I'll try it out this afternoon.

...hopefully, that's it!

Thank you very much for your help!!!

'On Saturday, I unscrewed the vacuum hose and noticed that the VTG linkage was getting stuck after about 3mm of movement... and then things started. Moving it up and down 100 times definitely wasn't enough. After half an hour, I thought it wasn't going to work (it felt like trying to pull two magnets apart). Then we continued at around 4000 RPM, and after another quarter of an hour, the problem was solved; the linkage no longer had any resistance.'

Get on the highway and really put your foot down... 200 km/h... what a joy!!!

... so, thank you again. If I hadn't looked into this, I would have had to have VAG install a new turbocharger for me...

Great, that's something .

Good luck, and hopefully it won't get stuck again.

Best regards, Rainer.

Rainer K. wrote:

Good luck that it doesn't get stuck again.

Hello.

If Andy is as lucky as I am, the theater will be up and running again in just a few weeks .

He can, just to be on the safe side, inquire about the current prices for a large battery pack .
--> Murphy's Law: when you are optimally prepared, the expected or feared event does not occur .

Okay, I'm ready. Please provide the German text you want me to translate.

Murphy's Law is probably more like, 'No matter what you prepare for, something unexpected is sure to happen.' So, it's the opposite of what you said. From my experience, it's like this: When you prepare, something still happens despite .