1.9 TDI ASZ Manual Transmission - Slight Idle Jerk

Hello,
Our Seat Ibiza ASZ TDI with 280,000 km has a slight hesitation when idling.
When the clutch is depressed, the jerking almost completely disappears. It's probably due to the electrical coupling switch.
"It sends a signal to the MSG and apparently changes something about the injection process without altering the engine speed?"
AGR LMM sensors were newly installed about a year ago (all original parts).

Okay, so if the alternator has to provide more power at idle (e.g., for the rear window heater or an electric auxiliary heater), it tends to fluctuate or vibrate a bit more.

Could it also be due to the Lima free-running feature?
I replaced this one 10 years ago because it was making noises.

At my daughter's allergy center, the underlying cause was identified as ZMS.

Thank you, Rüdi. I had it replaced by Seat at approximately 240,000 km.

Hi,
One possibility would be one or more faulty fuel injectors. Therefore, check the idle speed control or the individual cylinder corrections. You should specifically look at the effects related to load changes.
You've already mentioned the second one, which is the alternator's free-running mode.
hg
Herbert.

Thank you, Herbert.
Can the free-running clutch be checked effectively?
He hasn't made any noise so far.
All the PDE elements, etc., are still original.
If that were the case, you would definitely need to overhaul the cylinder head, including the camshafts and related components.

I'll start by looking at the idle speed control.

Quote:

Is it possible to meaningfully check the freewheel?

Remove the belt and check the pulley by hand (rotate it against the rotor). In one direction, it must be able to rotate freely.
hg
Herbert.

Then I'll remove the belt and let the engine idle without the alternator.
I'll let you know tonight what the results are.

Possibly, the PD cable harness is also the cause.

The wiring harness is still original. Since the slight hesitation only occurs when idling, I would rule that out for now.

Herbert, the idle speed control shows readings of -0.00 to -0.12 for cylinders 1-3, while cylinder 4 fluctuates between +0.19 and +0.26.
Unfortunately, it's barely shaking today.

The belt came off without any modifications, and the freewheel mechanism is working.

Can the idle speed be easily increased?

What happens without an alternator when you add a load? Light, climate control, rear window, fan, ...
What does the LLR indicate?
hg
Herbert.

kiter wrote:

Thank you, Rüdi. I had it replaced by Seat at approximately 240,000 km.

"Mine only lasted 18,000 km after the replacement. Audi had to replace it with a new one at their own expense after 9 months." I have no idea what mistakes they made during the installation.

Herbert Riemen is at it again .
Do belt-driven e-bikes offer any advantages?
I increased the idle speed from 903 to 924 RPM.
For the past 20 years, the car has consistently been fueled with Aral gasoline.
Does it make any difference to use Ultimate gasoline or to add fuel injector cleaner to the tank?

Wouldn't it be a good idea to have the common rail injectors (check/replace) resealed and have the injector control cables replaced at 280,000 km?
Unfortunately, the driving profile has been mostly short distances for the past 7 years (twice 20 km).
The Ibiza is rust-free and in excellent condition with regards to maintenance.

kiter wrote:

Herbert Riemen is at it again . Do belt-driven e-bikes offer any advantages? I increased the idle speed from 903 to 924 RPM. For the past 20 years, the car has consistently been fueled with Aral gasoline. Does it make any difference to add Ultimate gasoline or fuel injector cleaner to the tank?

"Stuttering" is very subjective; could you make a video where we can hear it?

Misfires can also occur if the EGR rate is too high, which can happen if the mass airflow sensor (MAF) measures too much air. Does changing the specified LMM (likely referring to a Mass Air Flow sensor) affect the engine's performance?

Best regards, Rainer.

kiter wrote:

Does it make any difference to add Ultimate gasoline or fuel injector cleaner to the tank?

I had two cars for 16 years. Here's the translation:

"We have one car that's a real gas guzzler, driven about 40,000-60,000 km per year on the highway, and family cars that are used 70% of the time for short trips with the kids, covering approximately 15,000 km per year."

I have a feeling that the latter have greatly benefited from me adding half a can of "LIQUI MOLY Pro-Line Diesel System Cleaner" twice a year.

By the way, my 3.0 TDI that I bought used also has the same problem.

Hello Rainer,
I replaced the LMM (lambda sensor) and AGR (exhaust gas recirculation) valve 2-3 years ago (always with original parts).
I will unplug the LMM connector tonight and report back.
The shaking is almost impossible to capture on video because it's only barely noticeable. I'm still trying.

The vehicle always starts perfectly and immediately, even after two weeks of inactivity.
The intake manifold has never been cleaned, and the EGR system is fully functional, just like it was from the factory.