ASZ Full Load Adjustments: 1700-3000 U/min

Hello,

It's about a 2003 Volkswagen Golf 4 with a 1.9-liter ASZ engine producing 130 horsepower, and it has 384,000 kilometers on the odometer.

The ZR (tensioner), water pump, and tension/idler pulley were replaced on the vehicle. The synchronization angle is -1.7°. (I hope there is no connection between this and the fault.)

"Now, under full load within the specified speed range, there is a significant jerking/hesitation. It feels like the right wheel is slipping, causing it to bounce up and down/thump. It's noticeable from 3rd gear onwards, and in 5th and 6th gear, it's so severe that it barely accelerates even on a flat surface."

Approximately half a year ago, the fuel injectors were resealed because the engine was only starting after a long cranking process when the fuel tank was less than half full. This issue was resolved.

The AGR valve has now been cleaned. The mass airflow sensor has been temporarily replaced with a new one from Pierburg, and the piping in the cylinder head is also new. Oh, and I also replaced the thermostat and coolant temperature sensor, along with the water pump, at the same time. The diesel filter is only about 1000 km old. The hydraulic lifters and camshaft look "like new"...

The idle speed control is specified in mg/H.

Zyl1: -0.6
Zyl2: 1.0
Zyl3: -0.8
Zyl4: 0.3

Greetings from the Upper Palatinate.

Hello,

The LLR is unremarkable, the synchronization angle isn't ideal, but it's unlikely to be the cause.
Check if the diagnostic functions also stop working when logging data. If so, there is likely a problem with the power supply to the engine control unit or with the engine control unit itself.
Also, here's the translation:

"Also, also check the PD cable harness in the ZK!"

Best regards, Rainer.

The wiring harness for the pressure sensors in the cylinder head is new. When reading the diagnostic data blocks while driving, there were no communication interruptions.

During the initial test drives, I noticed that when the engine jerks, the air mass drops by up to 200mg/H for a fraction of a second. However, the error memory remains empty, no matter how long I provoke this jerking.

Nash wrote:

What I noticed during the initial test drives is that the air mass dropped by up to 200mg/H for a fraction of a second when the engine was misfiring.

But the error memory remains empty, no matter how long I provoke this misfiring.
If I remember correctly, we had a similar issue with a broken wiring harness on the mass airflow sensor (MAF) in the forum, which caused the same effect. In your engine, the maximum possible fuel injection amount is only released when the mass airflow rate is sufficient.
Log whether the actual boost pressure drops first, and then the air mass, or vice versa.
It also makes sense to check the wiring of the mass airflow sensor (MAF) while monitoring the MAF values.

Best regards, Rainer.

Please also log MWB 18 and 23.
Are the hydro mounts and engine mounts definitely okay? It's often hard to tell when they're bad. I once had a Golf V with a similar issue, it was shaking, but not as severely as yours. There were no error codes or issues with the engine control unit (ECU). In that case, a hydro mount was broken, and I had to remove it in several pieces.

I'll take another look at the broken cable on the mass airflow sensor later, but right now the warehouse is full.

I have to say upfront that I've never really created any logs before... She operated the laptop, and I handled the gas pedal.

The first values are MWB 18 and 23. The 555 and 666 represent the full-load acceleration values with air mass and boost pressure.

Thank you in advance.

Is the actual boost pressure too high for this vehicle? Has a tuning box or chip tuning been installed?

dieselschrauber wrote:

For an AFN engine, the actual boost pressure is much too high. Is a tuning box or chip tuning installed?

Um, no. It's about an ASZ from a Golf 4 .

Okay, I thought it was related to the signature, but it's still too high for the ASZ.

Is the LMM an original part? The values are relatively high, even considering the excessively high boost pressure...
How did the error occur?

Best regards, Rainer.

I had a Bosch LMM (mass airflow sensor) originally, and for testing, I installed one from Pierburg. It provided the same readings...

Just finished a phone call with a customer. He mentioned that when he bought the car in 2006, with approximately 80,000 km on the odometer, he had it tuned up to 160 horsepower.

The error appeared "suddenly" after the alternator replacement. I had only disconnected the generator and moved it aside to get better access to the thermostat. During the test drive, it was raining, so I initially thought that perhaps a wheel was slipping.

Quote:

The error appeared "suddenly" after the timing belt replacement. I had only removed the generator and placed it aside to get better access to the thermostat. During the test drive, it was raining, so I initially thought that perhaps a wheel was slipping...

So, you changed the timing belt, and then the problem "appeared"? Well, I don't know...
It's strange that I can't detect any glitches in the log, which might be because the higher sampling rate isn't enabled when logging (there's a switch for that in the relevant screen).
"Relay 109" - has the issue been checked? Are there still no starting problems?

Best regards, Rainer.

dieselschrauber wrote:

So, you changed the ZR and then the error was "there"? Well, I don't know... "Relay 109" - has the issue been checked? Are there still no starting problems? Best regards, Rainer

Yep, right after changing the timing belt. That's the only thing I've done. I've been staring at the engine bay and going over all the steps again and again, but that's it.

The starting problems are gone; it now starts on the first turn.

I've created another log, this time only including air mass and boost pressure.

Hi,

Why didn't you group the measurements in the log to improve the temporal resolution? The speed (RPM) would also have been helpful.

"When I look at the boost pressure in the log, the actual boost pressure increases to over 2620 mbar. That's quite high for 160 horsepower. The largely identical BPX engine achieves the standard 160 horsepower with less boost pressure."

"Please finally create a proper log with grouped measurements, including engine speed, current fuel injection amount, target boost pressure, and actual boost pressure."

See:
I am unable to access external URLs, so I cannot translate the text from the provided link. Please provide the text directly, and I will be happy to translate it for you.

It's possible that the tuning file is suboptimal, and the engine would, with too high actual boost pressure, a) trigger an error and b) enter a limp mode, drastically reducing performance.
If a clever person a) turns something off, b) it might still happen anyway...

Please provide an additional vehicle scan.

Best regards, Rainer.