1.9AFN Engine Problems: Common Issues & Fixes

Hello,

I had to install a new machine due to an engine failure.
During the initial test drive, I noticed that the engine runs very roughly when idling. Additionally, it doesn't really start to pull until around 3000 RPM.
No modifications, everything is stock.


What could that be?

Error log is empty. The pump is located in the corridor.

Loading pressure sometimes exceeding 2.5 bar!
Injection amount at idle: 4.3 mg.

I'm open to all suggestions!


Best regards from Hanover.

Over 2.5 bar of boost pressure ... How did you arrive at that value? Boost gauge reading, test drive? Actually, it should go into limp mode if it's above 1.5 bar for more than 5 seconds . Are you aware that the values in VAG Com are given in millibars...? So, subtract atmospheric pressure and you get your actual boost pressure .

Is the valve timing gear (VTG) easy to operate? Does the VTG shaft pull approximately 1 cm when starting?
I had a very similar problem with my car... the full boost pressure didn't kick in until 2800 RPM! The issue was the turbocharger wastegate control valve (solenoid valve).

Thank you for the quick response.
It was measured with VAG COM, and it indicated a value of 2470 mbar.
The shaft of the charger can only be moved back and forth about 1/2 cm with your hand.


Best regards.


Okay, Passat 3B, manufactured in 1999.

Is that the large pressure vessel at the top of the VTG rod?
Possibly the membrane is already too soft, and the can can no longer withstand the pressure.
I can also move the VTG relatively well manually. However, when I go into the actuator diagnostics in VAG-COM and activate the boost pressure control valve there, the vacuum pump often just makes a "pop" sound, and nothing moves.
Please check that. The engine must be running.

Regards,
macro

makrospex wrote:

If I go into the actuator diagnostics in VAG-COM and have the turbocharger control valve activated there, the diaphragm often only makes a "pop" sound, and nothing moves. Please check this. The engine must be running

.
Hmm?
I'm familiar with this from the G3 AFN, but it's different: When switching between VTG open and closed positions, the vacuum reservoir is activated each time, and this pulls the rod to its limit several times even when the engine is not running.
With further switching, the hub will gradually become smaller.

Yes, that's correct.

Apparently, the membrane in my pressure sensor (Passat MJ95) is already so soft that it no longer functions correctly even with slight resistance from the VTG mechanism.
The test with the disposable syringe confirms this as well: The variable geometry turbine (VTG) can still be moved manually, but it is stuck when attempting to move it using vacuum pressure.
You only hear a "plop" sound, but there's no visible movement of the VTG rod.

I found a junkyard about 40 km away, and I'll probably go there soon (after the clutch is replaced) to look for a larger pressure vessel.
As far as I can remember, you already had those installed, didn't you, Ulf?
I haven't heard anything bad about it so far...

Regards,
macro

Hey everyone,
I'll look into that VTG thing. But I think the engine damage might have completely seized up the turbocharger.



I'll try out the actuator diagnostics. Also, the rod for the VVT (variable valve timing) has been adjusted incorrectly.




Best regards.

makrospex wrote:

I found a junkyard about 40 km away, and I'll probably go there soon (after the troublesome clutch is fixed) to look for a larger pressure vessel. As far as I can remember, you already had those installed at your place, right, Ulf?

Yes, I used it in my old AFN (Air Filter Needle). That fixed the problem and the loader is working perfectly again.

Okay, so the actuator diagnosis... the VTG valve is responding normally... but my linkage is completely misadjusted and the turbocharger is probably full of carbon.


Does anyone know how I need to adjust the rod?



Best regards.

3BVari wrote:

Does anyone know how I need to adjust the rod?

Yes: the technical article about VTG loaders and their settings .

Hi there...

I've now removed my load because the VTG (vertical transport gripper) is hardly moving at all.
I'd like to try cleaning it now, but I can't seem to get the casing off. Does anyone know a trick for this?


Best regards.

3BVari wrote:

Hi... I'd like to try cleaning it now, but I can't seem to get the casing off. Does anyone know a trick for this?

Yes, make sure all the screws are loose and give it a gentle tap...

already tried it, but unfortunately nothing happened.
and I didn't want to be too harsh about it...
Thank you for the quick response!


Best regards.

"I have the VNT20 turbo, and on mine, the housing is only held in place by screws. I'm wondering if anyone else with a similar turbo can check to see if there's an additional locking mechanism (like a twist-lock, although I can't imagine that). If it's like mine, you'll need to insert a piece of wood and gently tap around the edges. The housing might be stuck due to rust and soot."

Did you also remove the screws from the pressure vessel?

Yes, all the screws are removed. I have a VNT15, and as can be seen in the pictures from the English manual, it shouldn't be additionally locked.
Is it advisable to avoid heating the enclosure?



Best regards.

I can't imagine that. Do you know how hot it gets from the exhaust fumes?