Problems with the BSU engine (VW Caddy)

Old car, new problem: VW Caddy, 1.9 liter engine, 75 horsepower, engine code BSU, 120,000 km mileage.
Specifically, when I let it idle (without any electrical loads), it runs perfectly. However, when I turn on the electrical components, the engine speed fluctuates wildly (from 600 to 900 RPM) and it almost stalls. It's the same when driving between 1000-2000 RPM; if I stay in that range for a longer time, it starts to stutter noticeably. I'm now worried about a potential transmission problem (error memory is empty).
Checked/renewed: NW (water pump, replaced), MAF sensor (replaced), EGR valve (replaced), all pressures checked (boost pressure, tandem pump pressure). Engine control unit reset.
The "Friendly" is also at a loss now.
Can VCDS be used to adjust the idle speed, fuel injection curve, or EGR valve control? I've tried everything with the program, but I've completely failed.
Best regards,
Hanni

Quote:

Can the VCDS be used to adjust the idle speed, fuel injection curve, or the control of the EGR valve?

That can't be diagnosed using the car's diagnostic system.

You could post a VCDS Autoscan and the engine control unit's measuring block 13, both with and without load. "In addition, I would like to know the fuel injection quantity (MWB 1) at idle, with the engine at operating temperature, both under load and without load."

Best regards, Rainer.

I will drive to the friendly store tomorrow, save the mwb (presumably a product code or identifier), and post it here.
Thank you very much.

Then there will be no support, what's the point of having your diagnostic system?

I'll bring my laptop, plug it in, and retrieve the data.
What do I need a diagnostic system for? I have a 6VW and I handle the service and maintenance myself, so it's always a good thing to be able to postpone service intervals and read and clear error codes.

Hi Hanni!

Rainer means that you should connect your VCDS device, take a log of the following control modules (OBD data): 13.1, 18, 23, and also control module 1, and then upload the log file here.
...you don't need a workshop for that, because they can only give you instantaneous readings, not a log, and those readings are often useless.

"Another question: Is this the same Caddy with the worn camshaft?"

Best regards from Munich!

Okay, that was obvious to me. They often stand in front of them like Teletubbies and always assume they are police officers. Yes, that's the same one with the worn camshaft (pictures are already online).
Best regards, Hanni.

Okay, let's go: Create logs and upload them!

Okay, I will.
Okay, let me rephrase the question: When the engine is idling, does the engine control unit (ECU) activate the EGR valve in the millisecond range (as measured with an oscilloscope)? If it's open, shouldn't the EGR valve be constantly powered, providing a consistent 12V signal during idle?
Best regards, hanni.

Just do it.
Actions speak louder than words.

Best regards from Munich!

So, today I was planning to go to the friendly mechanic to get the measurements, but I received a call saying they found an error: the mass airflow sensor (MAF) is defective. They had a comparable vehicle available and swapped out the mass airflow sensor (MAF). Sure enough, it worked. They then installed the MAF sensor from my engine into the comparable vehicle, and the same problem occurred.
Okay, so the VW Caddy with the BSU engine is not running smoothly at idle and is shaking up to 2000 RPM. Check the mass airflow sensor (MAF) and possibly replace it, but not with aftermarket parts (I learned that the hard way; it was 60 euros cheaper, but the quality was not good). It's better to spend a few more euros and use original parts.
Best regards, Hanni.

Hello,

I don't want to offend you, but replacing the mass airflow sensor (MAF) based on the suspicion of "running poorly at idle and misfiring," especially when you have VCDS and could simply check the air mass values, isn't very smart.

There are still plenty of other possible causes for this type of error, so there's really nothing to remember.

Best regards, Rainer.

Yes, that's certainly possible. It could also be a worn camshaft, faulty piezo injectors, or something else.
However, if you've replaced your mass airflow sensor with a cheap, low-quality one and it's not working correctly, you shouldn't be surprised.
Best regards,
Hanni