TDI: A Sudden "Jerk" or "Surge"?

Hello,

I'm not sure if this is normal.

My TDI jerks or stutters after I release the accelerator pedal (for about 4 seconds) and then press it again.
It's not a strong pull, but it's noticeable.
And it's mechanical!
The engine is working fine.

I suspect it's the turbocharger boost pressure, which decreases when you keep your foot off the accelerator for a longer period and then quickly builds up again when you press the accelerator, causing that slight jerk.

Who knows?

Best regards and thank you in advance!

DJ.


Vehicle details: Volkswagen Golf III, GT TDI, engine code AFN, year of manufacture: 1997.

Hey TDI experts! Does anyone here know anything about this???



Regards,
DJ.

Remote diagnosis is difficult...

It could also be a problem with the drivetrain.

CU Gremlin.

Hi,

'However, this doesn't happen in the first or second gear.'

Regards,
DJ.

Okay, could you please describe that in more detail? If it only happens in certain gears, and Gremlin says to rule out the drivetrain, then it can't be a drivetrain issue. How strong is the jerkiness? Is it always there? What do you mean by "4 seconds"? Do you take your foot off the accelerator for four seconds, and then when you accelerate again, does it jerk? Could it be a sudden surge of turbo pressure (related to EGR problems), or does it jerk immediately?

Hmm, drivetrain - I can hardly believe it.
The car is from the year 1997, it's a first owner vehicle with 120,000 km, and it's like new !

Okay, so when I release the accelerator pedal (for at least 4 seconds) and then press it again, whether it's a light or full throttle, this jerk occurs.
It could be related to the turbocharger boost pressure, right?
Does it decrease when I release the accelerator?

What are AGR issues?

It's a slight jerk! Don't you experience that with your TDIs?

I just want to know if this is normal or if something might be wrong.


Thank you for your help!

Regards,
DJ.

To me, this sounds like a classic issue with the drivetrain. There's always some movement in the drivetrain, even in new cars (just think about how many rubber bushings there are!).

It could also be worn rubber bushings (suspension mounts, engine mounts), for example due to frequent driving on rough roads, or drive shafts (e.g., due to a damaged boot). However, this cannot be diagnosed remotely; you'll need to inspect it yourself.

Conclusion: As long as it's a gentle vibration, that's normal. If the vibration becomes stronger or you hear noises along with it, then you need to investigate (or have someone else investigate) where the problem is occurring.

Regards,
Private.

EDIT: I'm not familiar with the turbo building pressure so abruptly that it causes a noticeable 'jerk,' even with boost overshoots. That would be more of a clearly 'increasing thrust' rather than a 'jerk.'

dj1 wrote:

My TDI jerks after I take my foot off the gas (for about 4 seconds) and then put it back on the gas. It's not a strong pull, but it's noticeable.

My AXR also did that once. It didn't do it while the EGR was defective .
After that, I got a new engine control unit (ECU). The EGR parameters were set differently in the new ECU, and the engine no longer exhibited that jerking behavior.

Sorry, I'm new here?

What is AGR?


Regards,
DJ.

Sorry, I'm new here?

What is AGR?


Regards,
DJ

Dear DJ1, please be kind and use the search function. If you only read the last post of each thread, it's understandable why you might not fully understand what's going on. Thank you.

AGR = Exhaust Gas Recirculation (EGR)

But a silly question: When the engine switches to afterburner mode, does the air intake/bypass valve close? Or does the engine continue to draw in air even in afterburner mode?

Hi,

joegolf wrote:

But let me ask a silly question: When the engine switches to afterburner mode, does the air intake/bypass valve close?? Or does the engine continue to draw in air even in afterburner mode??

It probably depends on the engine (engine control unit).
The AGR (Abgasrückführung) valve in my AXR engine is partially open during operation. I can't tell you why.

Hello!

Can someone please tell me where the connector for the EGR valve is located?

I want to try removing it for testing purposes (I know, error entry), because mine is producing a lot of smoke.

Perhaps with a photo .

Good morning!

Okay: it's a TDI engine with the AHU code.

Hello,

"On my engine, there's a thin hose with a fabric covering connected to what I believe is a 'vacuum valve'. This valve is located on the back left side under the engine cover. Where this part connects, there's usually a rubber cap (which is missing on older TDI models, where you can see the valve directly)."
In a Volkswagen Golf, this component might be located in the rear right-hand side (since the engine is mounted transversely in the Golf).

To disable the AGR (Abgasrückführung), simply disconnect the hose mentioned above. Seal the hose with a suitable screw to prevent dust from entering the system. It's also advisable to seal the container.

Greetings.

Hello,

I have decommissioned the AGR.

Rucker is gone now. Hmm... well, I'm okay with that.


Regards,
DJ.

dj1 wrote:

Hello, I have decommissioned the AGR. Rucker is gone now. Hmm... well, I'm okay with that.

.... sounds so familiar to me? Where from, though?

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.
Okay, I understand. Please provide the German text you want me to translate into English. I will only provide the translation.