1.9 TDI ASZ Misfire: Causes & Fixes

Hello, dear forum.

My current case: a Seat Leon 1.9 TDI with 96kW (ASZ engine).
The engine runs smoothly at idle and has full power.
Unfortunately, it vibrates the most at 1800 RPM, and the vibration increases at higher RPMs.
The speed will decrease. The load doesn't matter, whether it's in gliding mode, partial load, or full load.
It's stuttering. Even when the car is stationary, you can feel it when you increase the RPM to 1800.
a shaking.
The only notable feature in the measurement data is in the correction for running smoothness.
1. Cylinder -0.6
Cylinder 2: -0.7
3. Cylinder - 0.7
4. Cylinder + 2.0

I have done:
AGR cleaned and temporarily disabled for testing.
VTG rods inspected for functionality.
PD component wiring harness replaced.

What would you consider doing next?
But what about the PD element, cylinder 4?

Hi,

According to the idle speed control system, the PD element is supplying slightly too little fuel to cylinder number 4 at idle, but the value is still within the acceptable range.
Since you mentioned that the jerking also occurs in coasting mode (with zero fuel injection), I'm less inclined to suspect a problem with a common rail injector.

It's possible that the dual-mass flywheel is worn out. I would also check if all four fuel injectors are still securely seated in the cylinder head, as the cylinder head cover can be easily removed on this engine. Have you already performed a pressure test on the fuel supply line at the cylinder head?

A video (which can be uploaded here) might also be helpful.

Best regards, Rainer.

Hello Rainer,
Thank you for the quick response!
I also suspected a fuel supply problem, which is why I also checked the fuel filter.
Already switched.
A tandem pump system would also be another option.
Is there a practical solution for pressure drop testing?
I'm not entirely convinced by ZMS because it's completely independent of torque.
And as mentioned, even when stationary, it noticeably vibrates at 1800 RPM.

The PD elements are fixed. Yesterday, I removed the cover to rewire the cable harness of the PD elements.
"Push operation" might have been poorly phrased. A better description would be...
It also vibrates when driving downhill and you slightly press the accelerator.
When you let off the gas, there's no more hesitation.

I think the problem must be related to the engine, specifically something before the dual-mass flywheel (ZMS).
Best regards,

TDIMaster wrote:

The term "sliding operation" might have been poorly phrased. A better description would be... It also vibrates when driving downhill and you slightly press the accelerator. If you're running out of gas - no more jerking.

Push operation = no gas.

Okay, then it could be due to a PD element and probably not the dual-mass flywheel.

Could you please check the PD element number 4? The motor should also be running with 3 cylinders.
Then, if the engine control unit allows it (I haven't tried it myself yet), you might be able to give it a spin and see if it jerks.
The engine will run unevenly, but it shouldn't jerk or sputter.

Best regards, Rainer.

Hello forum,

To provide an update on the current status of the issue:

I strongly suspect that the problem is caused by a worn-out clutch master cylinder.
Over the weekend, the ZMS finally gave up and is now making a rattling noise as it runs.
The first week of January will see a conversion to a single-mass flywheel, and I...
I will provide an update on the case in the new year.

Hi,

Thank you for your feedback!

Best regards, Rainer.

Okay.
The Valeo retrofit kit was installed on the EMS (Engine Management System).
"I'm satisfied with it. The vibration/shaking is gone. When I drive with a very light load at 1800 RPM, I still notice a slight vibration coming from the motor, but it's now only transmitted to the drive system to a minimal extent."
If you don't know about it, you probably wouldn't notice. If you really wanted to do a good job, you could continue working on the PD element.

Best regards and a happy 2017 to you!
Sascha.