Nice of you... | Posts 16+

Hi.

... that you keep us informed .

These kinds of errors are actually quite rare (at least in terms of encountering them), and you can definitely learn something from them.

"@Rainer: This seems like a case for the error database – perhaps in a slightly more general form?"

Hello Ulf,

Yes, effects like that should be included in the error database. However, for time-saving reasons, I would simply include the entire thread.

Best regards, Rainer.

Hi Ulf, Hi Rainer.
For simplicity's sake, I would also like to create a shortened version for the error database to save other users the trouble of searching.


By the way, I had the opportunity to drive a few kilometers on the highway this afternoon.
Unfortunately, the issue where performance drops off around 3000 RPM and only partially recovers by adjusting the throttle is still present.

What is not quite as urgent to clarify at the moment...


I'm going to prepare a post for the error database now...

... so it's definitely the throttle position sensor...

The immobilizer has nothing to do with this. It's only checked once when the ignition is turned on, and then never again.

The idle speed of 1300 RPM also suggests this, which is typical when the sensor fails. The increased idle speed is a way to keep the engine running, even if it's not performing optimally.

CU Gremlin.

Hi Rainer, Hi Gremlin, Hi Ulf, and hi to everyone else who has read this far.

To date, there have been no further instances of accelerator or engine malfunctions since the repair to the warranty seal.
I suspect there's a connection between the instability and the stability of the motor control system.

This morning, Uwe finally had the time and opportunity to take a test drive with a vehicle from Volkswagen, specifically a model from 1951.
While doing so (I was driving, he was operating the device), he queried various values on the display.
His observation: the LMM should have a value of 1000 (or something around that, he definitely mentioned something close to 1000) at 3000 RPM, but according to the diagnostic reading, it only has a value of 700 something. Since I was driving, these numbers are just approximations; it doesn't mean that he couldn't read it, but rather that I didn't remember it as accurately.

@Rainer
Oh yes, the turbo is probably okay. He said that no abnormal value is displayed there. Your concern (PM) seems not to be justified... Fortunately!

Uwe is now getting me a language model (LLM) that I can test for a few days.
I will keep you updated.
Best regards.
Sure, here is the translation of the text from German to English:

'Micha' translates to 'Michael' in English.

micha_passat wrote:

...To this day, there have been no more instances of the accelerator or engine cutting out after the repair to the WFS (Window Film System) lock. I suspect a connection between the instability and the stability of the motor control system.

Hello, well that's okay then .

Best regards, Rainer.

Hi Rainer.
It would have been so nice.
So, we installed the mass airflow sensor on Thursday, and of course, I immediately took it for a test drive.
Unfortunately, there was no change to my problem.
It starts to limit power at 2900 RPM in the 5th gear.
When you release the gas and then reapply it, the reading goes up to 3100.
Then I'm roughly at 140. (with the 215/40/17 tires, the speedometer is no longer that accurate)
Please provide the German text you would like me to translate into English.
But we wanted to go to my parents' place, and we had no other option.
So, I'm taking the train and driving about 300 kilometers (to the Ruhr area).
The speed was consistently around 140 km/h, but usually a bit less than that.
After approximately 250 kilometers, a first glimmer of hope appeared.
The car was slowly accelerating on a straight road to 160 km/h.
Unfortunately, traffic got heavier again, and I had to slow down to 100 [km/h].
After that, there was no more speeding.
On the return trip, I started experiencing that same effect again after about 70 kilometers, and it intensified, causing my speed to reach up to 170 km/h by the end.
Since I still received the error message 'Intermittent difference in intake manifold pressure regulation' (from Uwe) on Friday morning, I suspect there's a faulty turbocharger solenoid valve ('Russ') in the system, as described in the error database under 'Sticking VTG / frequent limp mode, intermittent difference in intake manifold pressure regulation.'

Now, according to a conversation on Friday morning, the KD master at VW doesn't even know if my car has a VTG (Variable Turbine Geometry). Where can I find this information out again?
There should be a can somewhere on the turbo, right?
(okay, I have a much better understanding of PCs .
I will take some time tomorrow or sometime like that to open the hood in daylight and take a close look.
I'll keep you updated.
best regards, Micha

Hi Micha,

You have a 1Z engine, so it's a wastegate instead of a VTG (Variable Turbine Geometry). But that doesn't matter, it can still get stuck. I also have a 35i. Let me tell you: it's really difficult to access (especially in a hobby workshop without a lift). You need to remove the plastic undertray (noise insulation or something) – it's held on by 6 screws, attached at the front of the bumper. Then you can see the turbocharger and the pressure regulator behind the engine block. I couldn't adjust the linkage by hand. Unfortunately, I don't know if that's normal!
I then detached the hose from the can and blew air into it. Then I looked something like this . Otherwise, nothing else happened. With compressed air from the compressor, the part then moved.
It would be interesting to know how easily or stiffly your pole moves.

Unfortunately, when the hood is open on the 35i, you can't see anything because the pipes for the coolant, EGR valve, and intake manifold are in the way.

Best regards.
David.

Hello doctor.
Thank you for the information!
Okay, so I'll take some time in the next few days to examine my car from underneath.
I'll keep you updated...

Hello everyone. Recently, I've noticed the same problem on my TDI from 3/1997 with 90 horsepower .

At a higher speed of 140 km/h and 3000 RPM, the engine runs out of breath. I swapped the mass airflow sensor with my brother, and now I can't even reach 140 km/h (the road slightly slopes uphill and then levels out through a tunnel). Even on the flat section inside the tunnel, the speedometer doesn't go any higher.
Otherwise, the engine runs normally and no significant issues can be detected.

Hi.

Can you at least perform a measurement run with data logging (air mass, boost pressure, engine speed, fuel injection volume)?

No, not like that, the way you're doing it.
I would have to go to a workshop for that.


Could it be that the boost pressure limiting valve is defective, as it's making a ticking sound?

Hi.

There have been several discussions here about the turbocharger wastegate solenoid valve on the 1Z engine, often related to its susceptibility to wear and tear or age-related issues, which typically manifests as a loss of power.
Swapping things around usually fixed the problem.

Of course, there's no guarantee that it will be the same with your car...

Hello everyone.
Finally, on Friday, I had the opportunity to go for a test drive with Uwe again. We took along a VAG 51xx diagnostic tool (I don't remember the exact model now) and headed onto the highway.
Surprisingly, he initially only reached the aforementioned speed of 140 km/h.
After only 2-3 minutes, he reached 170 km/h again (using the same trick of releasing and then pressing the accelerator).
I think that the wastegate might have been 'burned out' because I haven't been shifting as early as usual lately...
Uwe definitely compared the expected values with the actual values.
The LMM now has the exact target values. Therefore, the replacement was obviously worthwhile, but of course also expensive...
According to Uwe's statement, the turbocharger values are also okay.
and the other values related to fuel injection were probably also okay.
Uwe once went through the menus of the tester, looking for anomalies, but he didn't find anything.
So far, so good.

The search continues, because the next day, the effect was again present at both 2900 and 3100.
Now that we've received quite positive feedback about Mr. Müller (regarding OBD-2 diagnostics), we've considered purchasing the diagnostic software along with the cable in order to become independent from Volkswagen.
Does anyone know if error entries become immediately visible during long-term measurements when they occur?

I would be very grateful for any information.

But at least he's driving a bit faster now...

Hello,

micha_passat wrote:

...Anyway, Uwe then compared the desired values with the actual values. The LMM is now at the exact target values. Therefore, the replacement was obviously worthwhile, but of course also expensive... According to Uwe's statement, the turbocharger values are also okay. and the other values related to fuel injection were probably also okay. Uwe once went through the menus of the tester, looking for anomalies, but he didn't find anything. So far, so good. The search continues, because the next day, the effect was again present at both 2900 and 3100.

Does that mean your car simply stops accelerating at 140/170 km/h, and there are no error codes stored?
If there's nothing in the text, you should:
- Check how long the diesel filter has been in use / replace it if necessary.
- Check the fuel tank vent (if necessary, take a test drive without the gas cap, stuffing verschandeln rags into the opening).
- Disconnect the hose between the diesel filter and the fuel injection pump, and try to draw diesel through it using a brake bleeding device or a vacuum pump.
- Check the hose between the diesel filter and the fuel injection pump for air bubbles or foam while the engine is running.
It's not just that something is clogged in the injection system.

Best regards, Rainer.

Hi Rainer,
Okay. The upward momentum simply 'flattens out' at both 2900 and 3100.
The error memory is clear. (or: There are no more errors in the error memory.)
The diesel filter is about 1 year old, and I didn't see any air bubbles when I last took a close look.
And the story about the fuel vent , sorry Rainer, would only be a relevant point if I couldn't reduce the effect after a while when driving at full throttle on the track , right?
On the other hand, it might be an indication that the ventilation somehow opens through the so-called 'sog' .

I suspect it's more likely related to the wastegate mentioned by DocSnydor, because the effect disappears after a while when driving at full throttle, or becomes less pronounced. And repeatedly lifting off and reapplying the accelerator causes me to exceed those speed limits again and again.
Perhaps the flap is indeed affected by the amount of soot.
I'm continuing to test it, and in the next few days, I'll finally take a look at the underside of the car... I just have a lot of driving to do right now.

I'll keep you updated.