Golf IV 1.6 AKL - slight jerking/hesitation

I have a Golf that vibrates slightly between 1500 RPM and 2500 RPM. It doesn't matter if it's under light load or full load; the vibration stops above 2500 RPM. Error memory is empty.


I once disconnected the oxygen sensor, but the problem persisted. All sensors checked, values are OK.
I also don't see any fluctuations in the LMM reading, although the control unit is probably too slow for that. At full load, I get 380-400 mg per injection.
I also replaced the spark plug wires because three different types had already been installed.
Finally, I cleaned the throttle valve actuator. I deleted the learned values and re-initialized them. It didn't bring anything that was expected.


Now I have a second error that is also visible in the automatic scan.

If I leave the car running without the air conditioning, everything is fine. However, if I turn on the air conditioning and give it some gas, it starts to "stutter" or "hesitate" at idle. And it also contains the error code 00533.


I then tested the throttle position sensor.
Supply voltage of potentiometer: 4.9 V --> OK.
Resistor DK 6 Ohms --> OK.
Power supply LL switch 12V -> also OK.

I was also unable to detect any vacuum leaks.

After the DK (throttle body) learning process, this bit pattern 00000100 indicates that the throttle control unit is de-energized (powered off). Is that normal? Does the control unit then switch off the voltage?

Hey Chili!

With the div. Regarding error entries in the Autoscan related to the alternator/generator, I would initially investigate this area.
Still puzzled, that after reconnecting the alternator AND pressing the accelerator, it makes a sawing noise.
How did you turn the breast pump on/off? Belts off?
Does the charging indicator light up when the ignition is turned on, even without the engine running?

Although it sounds like a classic vacuum leak, I would check the D+ line.

Best regards from Munich!

If I turn off the climate control using the ECO button, the sawing noise stops.
If I disconnect the pressure switch and the compressor is off, it continues to make noise, only stopping when I press the ECON button.

And if I let it idle with the air conditioning on, there's no squealing, only when I first press the accelerator.

Okay, Dieselbear, read from the beginning again, about how I ended up in Lima, you idiot. It's "Klima," not "Lima."

Check out this topic:
Okay, I'm ready. Please provide the German text you want me to translate.

Best regards, Rainer.

The issue of the engine "sawing" after acceleration in climate mode has been resolved. The pressure switch for the power steering was always making contact.

"Previously, there were no issues, but after the DK cleaning, the saw started making noise in the living room. It can't be that the pressure switch failed at the same moment."

Tomorrow I'll do another test drive to see if the slight jerking is gone, but I highly doubt it.


I suspect that the error code 00533 - Idle speed control 19-00 - lower limit value set occurs when the system cannot regulate the idle speed.
After starting, it ran at 830 RPM. When the air conditioning turned on, it went up to 930-960 RPM, and when I gave it some gas, it reached around 1300 RPM.
The value in MWB 8/3 was -5% after starting, and when the speed increased, it went to -6%, at which point the error was triggered.

With the pressure switch disconnected, it now runs at 800 RPM, and when the air conditioning is activated, it goes up to 860 RPM. MWB 8/3 between -2% and -3%.

Quote:

I suspect that the error 00533 - Idle speed control 19-00 - lower limit value is being set when it cannot regulate the idle speed.

Correct

bloesch wrote:

Possible symptoms for VAG fault code 00533: - high fuel consumption Possible causes: - vacuum leak between the mass airflow sensor (MAF) and the engine. - faulty injector(s) - fuel pressure regulation faulty. - faulty throttle valve - air filter is dirty. possible solutions: - throttle valve basic adjustment - Check hoses/intake manifold for leaks (e.g., using brake cleaner). - Check the air filter. - Check fuel pressure / fuel pressure regulator. - Check the EGR valve. - check the injector(s)