Boost pressure fluctuates at partial load, according to LDA

Hello everyone, again.

Yesterday, I noticed that my boost pressure (at approximately 100 km/h in 5th gear at 2000 rpm) fluctuates between 0.35 and 0.45 bar. How should I describe this...? Hmm.

So, it goes up to 0.45 bar, then it drops down to 0.35 bar approximately 2-3 times per second. Road is level, no wind, no acceleration due to driver (cruise control).

It's something I've never noticed before.

What can still be heard lately...
'When I'm driving in a high-revving range, I hear a 'chirping' sound somewhere between 2000 and 1200 rpm.'
It's like I have a bird in my exhaust pipe...

Thank you in advance for your responses...

Best regards from Graz, Michael.

Where did you connect the pressure gauge? If it's connected to the branch leading to the N75 valve, it's understandable that it fluctuates, as air is constantly being drawn from there for control adjustments. This causes the pressure to drop repeatedly.

The wastegate cannot open until it reaches a pressure of 0.45 bar. It should only start stirring at 0.6 bar.

I find it hard to believe that the actual boost pressure fluctuates so rapidly, as the boost pressure control system would be too slow to cause that (especially with a turbocharger equipped with a wastegate).

when I drive in a high-revving range, I hear a 'chirping' sound in the 2000-1200 rpm range.
It's like I have a bird in my exhaust pipe...


It could be several things. It might be the blower fan, so try selecting a different setting if it's making a chirping sound. Otherwise, you might also encounter issues like a sticking brake, worn slip rings on the alternator, etc.

I'm taking the boost pressure reading from the front of the intake manifold (charge pipe), where the hose connects to the interior towards the mass airflow sensor (MAF).
I simply installed a T-connector and used a 2-hose system to run it inside.
'I can hear a noise, and it definitely seems to be coming from the exhaust (manifold, turbo) or something like that. My ventilation is always set to 0.'
I noticed the fluctuations for the first time yesterday, and I've been using LDA for a while now.

My suspicion is that I have a leak somewhere in the LD system, because the LD is building up much too slowly. I only reach full LD at 2500 rpm.
'Speaking of the Gal (presumably a car model), if you drive one with a 70 horsepower naturally aspirated diesel engine up to 2200 RPM, you'll feel like someone is hitting you from behind with a giant sledgehammer. (I've been experiencing this problem for a while, and it's only getting worse).'

Best regards,
Michi.

Hi Michi,

Have you ever done a 3-8-11 log?

My 1Z also has a turbo, but it kicks in at 1600-1700 RPM.
If I drive without the LMM (lambda-controlled catalytic converter) but with a diode, the power is significantly reduced.

If your LMM is even more broken than mine, it might push the hammer to higher RPMs.

Does the turbo still engage when driving with a limited mass airflow sensor (MAF)? (Of course, the overall power output will be lower in that case.)

m;

Hi Michi,

Have you ever done a 3-8-11 log?

My 1Z also has a turbo, but it kicks in at 1600-1700 RPM.
If I drive without the LMM (lambda-controlled catalytic converter) but with a diode, the power is significantly reduced.

If your LMM is even more broken than mine, it might push the hammer to higher RPMs.

Does the turbo still engage when driving with a limited mass airflow sensor (MAF)? (Of course, the overall power output will be lower in that case.)

m;

The LLM seems okay. According to the logs, the initial value I set was 841 mg, so the target value should be correct. I haven't tried anything related to the diode.

Okay, I'll log in today, and then post something tomorrow.

Best regards,
Michi.

Perhaps have someone gently tap the mass airflow sensor (MAF) with the handle of a screwdriver, or have them manipulate the wiring. While doing this, log the engine's low-speed performance or observe whether there are any fluctuations. Possibly, the AGR valve is malfunctioning and venting exhaust gases (but this is less likely) - seal it with a metal plate.

hello

When I drive in a high-revving range, I hear a 'chirping' sound in the 2000-1200 rpm range.

You might have a small crack in the vacuum hose, or...
'There's a slight leak at a connection point, which is why your LDA...'
also these pressure fluctuations are displayed to you inside the vehicle...

greetings

hb2000

Perhaps you have a small crack in the vacuum hose or...
The connection point isn't completely sealed, which is why your LDA...
also these pressure fluctuations are displayed to you inside the vehicle


The 1Z/AHU has overpressure regulation, and the whistling occurs during acceleration - but the hose to the LDA could be the culprit, or the manometer itself. What kind of damper is installed before the LDA? Could that be it? Having problems?

A measurement with VAG COM could quickly reveal information about the turbocharger boost behavior - perhaps someone near you has one; For me (near Vienna), it would be quite a distance .

Okay, now I have a small log.
See for yourselves.

Either my Excel or yours is malfunctioning.

I have a large number of date values because everything is being converted from a format like "5.04" to a more descriptive format like "May 2004".
I believe that's the Excel program that created the file (i.e., yours), when it interprets the CSV.

"Furthermore, it would be great if you could create a preliminary graphic." If you want to know more precisely, you can always take another look at the data.

m;

Unfortunately, my Excel is acting up... I'm about to throw the whole thing away... Now I'm stuck here and can't get any of the graphics to work... ahhhhhhhhhhh.

It works with a different XLS file...


I hope I get it right this time...

Somewhere within the text converter, you need to configure it so that "period" and not "comma" is used as the decimal separator.

Here's the table and the chart again.

Nope, that was also a sentence containing the letter "X".

- Spaces in filenames are unnecessary and disrupt the download process.
- A CSV file cannot contain a chart, so there is none included .

m

Your N75 is desperately trying to boost the turbo pressure.

35.2% keystroke rate, but the turbo function doesn't do anything.
0.2 bar of boost pressure instead of the desired 0.8 bar (at 14.67 seconds).

Is your turbo stuck?
Does the shaft rotate easily with almost no play?
Does the wastegate close properly?

Yesterday, I was holding a turbocharger, and the wastegate (the cover on the arm) was rattling. Maybe something is stuck in yours. The pump rarely reaches its target pressure.

You should have kept the throttle open longer during the measurement; you never see the typical wave pattern of the turbocharger pressure regulation.

m;

I've replaced the file...