Schnorcheln/"Kaudern": bek. Fehler beim TDI AWX? | Posts 16+

There, at approximately 1900 RPM, it climbs the hill, and it 'pulls' the entire incline (for over 5 seconds).

'This is definitely not the same phenomenon as what I'm experiencing with my AXR.' And, personally, the prolonged resonance noises in the intake manifold when accelerating (if there are any) would give me cause for concern...

Regards,
Curtis.

I also hear that noise in my TDI.
Sometimes, when I'm driving in city traffic and quickly release the accelerator pedal under heavy load, I also hear that noise.
It sounds like a WRC car!

Bee wrote:

The noise only occurs when BOTH conditions are met: 1.) Speed approximately between 1800 and 2000 RPM. 2.) Accelerator pedal position set to a specific point (for me, it's somewhere around half-throttle).

Hmm, that might also be the sound of the turbocharger's pump.

I recall from my experience with AFN that, for example, when using approximately half throttle and climbing a hill, the boost pressure was definitely set higher than when using the flat ground setting.

Normally, when running the LDA at full throttle from the low RPM range in higher gears, you'll see two limiting marks where the pressure remains constant despite the increasing RPM.
The lower limit is up to just below 2000 rpm (which is likely the threshold to prevent pump cavitation), and after that, the pressure can continue to rise to its final value.

If the VTG (Variable Turbine Geometry) shaft is too short, it could potentially shift the operating point towards higher pressures in the low-speed range.
(The regulation doesn't work as a simple "should-be" versus "is" comparison, but rather uses reference values for the touch ratio, which are initially used, for example, during load changes.) Then, we briefly wait to see if the desired pressure is reached, and only then, if necessary, will we intervene to make a correction.

I would also like to try lengthening the VTG rod on Bee's vehicle.

Hi,

@Ulf: Doesn't increasing the engine's RPM reduce the maximum achievable boost pressure? Would you actually do that to a car with only 2808 kilometers on the odometer, or would you, with your extensive expertise, put pressure on a suitable workshop until the problem is resolved?
My dealer's suggestion: Wait and see if it gets louder. Then it can be easier to find .
Can anyone recommend a GOOD workshop in the Stuttgart/Leonberg area? Is there perhaps someone who could offer me expert advice on 'getting back on my feet'?

@Curtis: What do you mean by that?
'The presence of resonance noises in the intake manifold when accelerating (if there are any) would personally concern me...'

Regards,
Sure, here is the translation of the text from German to English:

'Micha'

Bee wrote:

@Ulf: By increasing the duration of the turbo spool-up, am I not reducing the maximum achievable boost pressure?

As long as you only adjust the "operating point" of the system, no - it just takes a little longer (fractions of a second) for the usual full pressure to be reached.

Quote:

Would you actually do that to a car that has only 2808 km on it, or would you, with your extensive expertise, put pressure on a corresponding workshop until the problem is resolved?

I would assemble it myself. If necessary, everything can be completely undone without a trace (except perhaps the torn piece of thread locker, but you can always buy more of that ).

It would probably take months for a (likely clueless) workshop to adjust the thing to exactly how I want it, if they would even agree to modify a "highly precise factory setting" in the first place...

@Ulf: To modify a 'highly precise factory setting'. :DWe share the same views on that.

What's the point of adjusting the operating point if the same operating condition is reached a few tenths of a second later?
(Sorry if this question is silly.) Unfortunately, I'm not an expert.

At the same time: On Monday, I'll use VAG-COM to take it for a short drive and see what the boost pressure is when the noise occurs. Perhaps this insight will be helpful.

Regards,
Sure, here is the translation of the text from German to English:

'Micha'

Bee wrote:

What's the point of adjusting the operating point if the same operating condition is reached a few tenths of a second later?

Perhaps a moment of calm before the "horse" .

Technically, the offset is shifted, which affects the behavior during the control process, and potentially even the final pressure achieved in certain operating conditions.

Just try it out - I think we've theorized enough .

Bee wrote:

Hi, I have an AXR model year 2005, and I'm experiencing a noise between 1800 and 2000 RPM during partial load operation. It sounds like a metal edge is vibrating and hitting something.

Recently, while replacing a headlight bulb on the front left side of my Golf, I removed the battery cover and discovered a noticeable abrasion mark!

The plastic cover had already become at least 2mm thinner on the left side, facing the direction of travel, because it constantly rubs against the air intake pipe of the air filter housing.
I stuck a thick strip of felt over it, and that was that for me!

I can imagine that it might be much more noticeable in a more extreme situation!
I think it's definitely worth checking out!

It is also possible that the underside of the transmission is rubbing against the lower engine cover!
The gearbox then comes into contact with these small plastic blocks located on the inside of the housing under certain load conditions.
The areas where the paint has been rubbed off should be clearly visible, but only on the transmission housing!

Simply cutting away the corresponding blocks, which presumably serve for noise insulation, is sufficient!

The problem affected the first 115 units of the PD model, and it was supposedly fixed afterward, but you never know!