Boost Pressure Difference VW Golf III

Hello,

'For the past few weeks, I've been having a problem with my Golf III TDI, 90 horsepower, manufactured in 1996, while driving on the highway.'

'Specifically, it sometimes switches to the emergency mode during longer trips, and then reduces power accordingly. You can barely reach speeds above 140 km/h, and uphill it's limited to a maximum of 90 km/h. If I turn the engine off and on again, it runs normally for a while, until it starts doing this again.'

I then borrowed a diagnostic connector and VAG-COM and identified the error.

00575 - Intake Manifold Pressure
17-10 - Control Difference - Intermittent

'I found it. I then measured the mass airflow sensor while driving (that's usually the first thing you check), but it doesn't seem to be the problem. However, when I maintain a constant throttle position for a while, the boost pressure is significantly lower than the target value, and the solenoid valve seems to be trying to adjust it, but apparently without much success. The maximum pressure is good, around 2000 mbar, when I give it full throttle.'

I once took two pictures using VAG-SCOPE.

http://129.13.103.40/smaus/images/bild1.gif

http://129.13.103.40/smaus/images/bild2.gif

Green indicates the actual pressure, turquoise indicates the target pressure, and blue represents the control range of the solenoid valve.

I suppose it's somewhere related to the turbocharger, solenoid valve, or pressure regulator. But how do I figure out exactly what's causing it?

Has anyone else perhaps experienced a similar problem?

Sure, no problem.

Steffen.

Hello Steffen,

Quote:

Has anyone perhaps ever had a similar problem?

If you had followed the tips after registering, you would have come across hundreds of search results on that topic.
Sure, please provide the text you would like me to translate.
- Commonality of the boost pressure control system in turbochargers.
- Install a new solenoid valve for testing the boost pressure regulation (it's not that expensive, and if it's intermittently malfunctioning, you'll drive yourself crazy trying to find the problem, so it's best to replace it or test a new one).

What is your engine code, 1Z?

I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

/viewtopic.php?t=3128

Best regards, Rainer.

Hello Rainer,

I had already read those articles, but they mostly refer to VTG turbochargers. I only have one with a wastegate, so I couldn't make any progress with that information.

I've searched for 'checking the wastegate' and similar terms, but I haven't found anything that explains how to determine which specific part is causing the problem.

I'm almost starting to doubt that the problem is with the valve. I mean, VAG-Com shows that it's regulating, but the boost pressure isn't responding to it. And the pressure is consistently too low when I accelerate smoothly, which makes sense.



Best regards, and thank you in advance.

Steffen.

Quote:

I mean, VAG-Com shows that it's regulating,

WRONG!!

VAG-COM indicates that it is being activated. However, VAG-COM cannot determine whether it is actually doing anything.

If it's broken, the COM still shows 34.2% (or something like that), but the device itself shows 100% or 0%, depending on its position.

Is it still audible and noticeable?

m

Quote:

VAG-COM indicates that it is being activated.

It's not always easy to determine whether the solenoid valve is stuck internally or simply malfunctioning intermittently.

Is your wastegate actuator common and not partially rusted?

Best regards, Rainer.

You're right, I hadn't thought of that. It could also be that the values are incorrect. I'll definitely try testing the valve tonight to see if it's working.

How can I check if the wastegate is functioning correctly? It's controlled by overpressure, so simply blowing air into a hose probably won't be enough, right?



Best regards,

Steffen.

You can only generate a maximum of 0.2 bar of pressure with your mouth!

I also could hardly believe it until I recently blew into my LDA.

And the wastegate should have a regulation pressure of 0.6 bar.

Take a pump.

m

I will do it .

I just found another page with a lot of information on how to check various parts.

http://www.msi-motor-service.com/pierburg/dt/produkte/pi.asp?kz=SI

Hi,

A large syringe is recommended... that should do the trick.

During the testing of my LDA, I used a 100 ml syringe. With that, I usually managed to reach 1 bar of pressure before the hose (which was loosely attached for testing purposes) burst.

1 bar is actually a lot of pressure when you generate it "manually."

Best regards,

Jan.

By the way, the solenoid valve costs 30 euros.

So, not quite the whole world .

m;

Hello Martin,

Quote:

WRONG !! VAG-COM indicates that it is being activated. However, VAG-COM cannot determine whether it is actually functioning correctly.

It's not entirely wrong because: It's a regulation, not a control (one of the nice quiz questions ). If it hangs, the system attempts to readjust based on the control variable (duty cycle). This continues until a certain point, at which the control unit detects that something is wrong > error entry.
Just like he did at the beginning, he's still pushing.
An implausible key press ratio would therefore already be an indication.


However, that doesn't change the possible causes, which are still the valve or the wastegate, so okay.

best regards
Albrecht.

Okay.

But I'm having trouble deciphering this Spartan VAG-SCOPE diagram right now.

"Furthermore, I don't know the target values for the duty cycle (and certainly not the typical behavior in relation to speed/load)."

I just bought the Rep guide yesterday and I've never looked at the keyboard shortcuts because the boost pressure has always been just right. (unlike the air mass).

Perhaps my 90-minute reference ride will help.

http://www.luxus-wg.de/~martin/auto_bilder/LOG-01-007-003-011.zip

Ah yes. Thank you for the tips and the diagram, that has already been helpful. In my case, the duty cycle is always at its maximum, and that's in the direction where the EDC is trying to increase (or control? That's a gray area, I would say ). And when I compare that to Martin's diagram, it looks quite different.

In the VAG-Scope images I posted, the top row represents group 003, and the bottom row represents group 011.


Best regards,

Steffen.

@stef42

I'm experiencing a similar problem, but in the opposite direction, I think. I drive until a certain point, then there's a jerk, and the car refuses to accelerate any further. I suspect the wastegate is stuck in my case. I'll need to check it out when I have vacation time (which won't be this year).

Best regards, WarLord.

Hello,

'Yesterday, I finally got around to checking everything out. It was indeed the solenoid valve, and to make matters worse, the hose to the pressure sensor was also cracked. But now it's working again. Thanks to everyone for their help.'



Best regards,

Steffen.

Great, thanks for the feedback!