TDI Shudder: Causes, Solutions & Troubleshooting

HI!

I found the following post in another forum; perhaps someone here has already seen it.
Since he describes the exact problem that I'm also experiencing with my 1Z, I wanted to ask you all what you think about it.
I particularly imagine it will be difficult to readjust the quantity control mechanism so that the motor runs normally again.

Okay, here's the post:
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Help, my Passat TDI, 90 hp, year 1994.
vibrates at constant speeds.
For example: 4th gear, 60 km/h, maintaining a constant speed.
The error memory does not indicate any faults.
Diesel filter and mass airflow sensor are okay/new.
The guys from the workshop can't do anything.
find/want to find the error by trial and error.
find. The problem: parts like needle lifter injectors, fuel injection pumps, turbochargers, or intercoolers.
They cost a lot of money.
I'd like to know what to expect beforehand.
Can someone help me?


Hello.
I've managed to solve the stuttering problem myself!
It was due to a problem with the metering unit of the fuel injection pump. Since replacing it (metering unit costing 600 euros plus installation, replacement fuel injection pump costing 700 euros plus installation = approximately 1000 euros) was too expensive for me, I decided to disassemble the metering unit myself. And sure enough, there was a significant amount of metal dust attached to the rotating magnet. I removed the dust, and the problem is no longer noticeable.

You can easily test this beforehand. Simply attach a strong magnet to the triangular screw where the gas cables enter --> the jerking will be reduced by 50%. Unfortunately, the magnet keeps falling off due to the vibrations and unevenness of the road, despite several attempts to glue it on. You can clearly feel when it's attached and when it's not.

To repair: Disconnect the cable, remove the cover, completely unscrew the fuel metering unit and place it on a table. Unscrew the contact cover, disconnect the cables from the gas (this requires breaking the spot welds of the contacts in the fuel metering unit - which can be re-soldered later), and loosen all the screws to remove the black plastic part. The magnet is located underneath. Remove any metal dust, reassemble everything, and the problem is solved!

Attention!!! Before disassembling, be sure to mark the exact position of all parts and reassemble them in the same way. The quantity control valve on the injection pump can be shifted a few millimeters to the left or right. This can result in the engine not starting or the idle speed being significantly too high. That's why all workshops say that nothing can be repaired on the injection pump and they want to replace it completely (for 1000 euros!).
It is absolutely essential to maintain absolute cleanliness; any dirt particles in the pump can be fatal!
To be able to loosen the setscrew, I used a Dremel multi-tool to cut a groove into it, and then I used a strong screwdriver to turn the screw out.

'Die Sonne scheint hell, und die Vögel zwitschern fröhlich. Ein leichter Wind weht durch die Bäume, und die Blätter rascheln leise. Es ist ein wunderschöner Tag, um draußen zu sein.'

So, it would be great if you could share your expertise on this.

Sure, here's the translation:

'By the way, what does he mean by 'triangular screw'?!'

Thank you.

BASTI!

Hello Basti,

The article sounds quite plausible. However, it would be important to find out where the metal shavings/dust in the fuel injection pump originated.
Because something has to dissolve in there, and I don't believe that a simple cleaning will be enough in the long run.
The metering unit is attached to the specified ESP with 3 Torx screws and one triangular screw. The triangular screw is presumably intended to prevent anyone from simply unscrewing it and looking inside.
The catch in that article: the marking of the position of the adjustable quantity setting using a pin or a "remember position" function is a joke. It doesn't work. In order for the EDC (Electronic Damping Control) to not detect an error during the control unit check AND for the car to drive properly again, the position (and therefore the quantity base setting) must be accurate to at least 0.1mm.
You can find instructions on how to regain that position in Ulf's article about a DIY solution for fixing the issue, which is available in the error database.
Alternatively, you can simply use a diagnostic tool to check the fuel injection quantity at idle, or the control valve actuator's starting positions during a start-up check, and then adjust the control accordingly.

Best regards, Rainer.

Rainer K. wrote:

... The dosing unit is attached to the specified ESP with 3 Torx screws.

Hello Rainer,

Older pumps may also have Allen screws (my 1Z did).

Otherwise, I have to agree with you. Saying you can just easily screw a VP37 on and off is a great joke.

Basti911 wrote:

One more thing: What does he mean by "triangular screw"?!?!

Hi,

Interesting thing . I built a tool for a triangular screw in 10 minutes, and here's how:

/viewtopic.php?t=1987&highlight=triangular_screw

Best regards, Christian.

Rainer K. wrote:

It would be important to find out where the metal shavings/dust in the injection pump are coming from. Because something has to dissolve in there, and sooner or later, I don't believe that a simple cleaning will be enough.

Hello everyone.

I think so too.

Before removing the MSW (main spindle unit), it's my opinion that you should first just remove the cover and manually check if the shaft is really difficult to turn (i.e., if it's jammed or sticking).

If that's the case, I would initially recommend following the DIY troubleshooting guide rather than disassembling the pump, which would require significant effort and carry a risk of errors.

It would be important to find out where the metal shavings/dust in the injection pump are coming from.
Because something has to dissolve in there, and I don't believe that a simple cleaning will be enough in the long run.


ei-jo....

It always depends on the operating hours. The first components to wear out are typically the feed pump, then the roller ring, the injection control valve, the high-pressure pump, and the metering unit with its sliding sleeve, etc.

'There will certainly be wear and tear, which will accumulate on the magnet of the turnout. Bosch also factors in a certain amount of wear over the operating life. This is clearly noticeable in the design guidelines regarding the initial amount [of material] .'

CU Gremlin.

I once tried messing around with a strong magnet near the cover of the fuel injection pump while the engine was running, because the car doesn't run smoothly even at idle (it has a kind of 'stuttering'; not always).

The problem is that the parts aren't particularly magnetic, which explains why the magnet didn't stick to that person.
It didn't really achieve much, although I'll test it again.

Could the problem also be caused by a faulty engine mount? I'm just confused because the car doesn't always run roughly at idle, but with a faulty engine mount, it should always be shaking.
The front bearing looks sealed.


Do you have any other TIPS?!?!??!


Thank you, BASTI!

Basti911 wrote:

I once tried messing around with a strong magnet on the cover of the fuel injection pump while the engine was running, because the car doesn't run smoothly even at idle (a kind of "thumping"; not always).

Hi Basti,

If it's an occasional "wrum wrum" sound, the fuel injection pump might be too rich (I experienced this with a 1Z engine) -> idle speed control problem. So, as Ulf mentioned above: use the search function: "diy-anti-vibration solution".

Best regards, Christian.

Does that also explain the jerking or stuttering at higher RPMs?

What do you think about the engine mount?

Hi, BASTI!

Basti911 wrote:

Does that also explain the jerking at higher RPMs???

Hi Basti,

It sounds more like a throttle body actuator! Mass airflow sensors can also sometimes cause these problems.

www.tdi-ruckeln.de

Basti911 wrote:

What do you think about the engine mount?

Okay, gently touch the gear shift lever and check if the transmission wobbles or moves excessively when shifting (e.g., when abruptly engaging the clutch). You might be able to detect faulty bearings this way!

Best regards, Christian.

I once tried using a magnet. However, it doesn't seem to do anything for me. The magnet (which is from an old hard drive }) does stick, but unfortunately, it doesn't fix the stuttering...

Well, I think he means a MAGNET and not a magnet .

The head motors from hard drives might seem impressive to a layperson, but I would probably opt for magnets for linear actuators (i.e., real ones). Monitor images distort from a distance of 90cm. They no longer detach from a smooth metal surface (nor do they detach from each other) and they crush fingers if you handle the carrier plates carelessly.

Unfortunately, it cannot and may not be sent by mail .

CU Gremlin.

Well, I think he means a MAGNET and not a magnet .



Thank you for the explanation. It's easy to understand. And I really thought they were already incredibly strong. I've also gotten quite injured by them before.
But if you take such a MEGA-MAGNET, doesn't it disrupt the entire system, instead of just attracting the metal shavings?

Considering their size, they are quite remarkable.

The problem with the pump, as usual, will be getting the correct size.

'However, I don't think a magnet from the head drive will be able to reach the quantity adjustment mechanism; its magnetic field orientation is simply too unfavorable for that.'

CU Gremlin.