Fuel Filter Problems: Engine Jerking & Hesitation

Hi!

Today, I took my Passat 1Z, which now has 330,000 km, to an independent repair shop because of the known jerking/shaking problem.
The expert believed that the cause of this problem was likely due to a dirty fuel filter in 80% of cases, as there were also visible air bubbles in the fuel hose leading to the ESP (Electronic Stability Program).

I suspect that the ESP (or the setpoint controller) is misconfigured, or is what this master technician was suggesting actually correct?

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Would you recommend bidding on and installing an ESP (with a new timing belt) from eBay, given the mileage, or is the risk of other mechanical failures too high, making the whole thing a waste of money?


Thank you.
Best regards, BASTI!

Hi,
Is that just a single bubble that isn't sucked away when idling, or is air being continuously drawn in?

Basti911 wrote:

Today, I took my Passat 1Z, which now has 330,000 km, to an independent repair shop because of the known jerking/shaking problem. The expert believed that the cause of this problem was 80 percent due to a clogged fuel filter, as air bubbles were also visible in the fuel hose leading to the ESP.

Hi Basti,

Good fuel efficiency . What exactly was replaced in the engine area? Please describe your jerking problem in more detail! Jerking in 5th gear at 50 km/h sounds like a large amount of switching. Sudden misfires at 3000 rpm after the needle lift valve. Please use the search function or check here: www.tdi-ruckeln.de

This is a typical example of partial load rocking (e.g., when driving at a constant load of 30 km/h in 2nd gear, or 85 km/h in 4th gear, etc.).
Even when idling, the engine makes a rumbling noise (a rhythmic 'wrum-wrum-wrumm').

If I'm not mistaken, are there constantly visible air bubbles?

I suspect it's the fuel injection pump, but if it were just the filter, that would be great .

Best regards, BASTI!

Basti911 wrote:

(like that rhythmic: wrumm-wrumm-wrumm)

Hi Basti,

"Ah, that sounds suspiciously like a rich ESP setting. Does the tachometer also fluctuate a bit with the tones? Due to the (too) rich pump setting, the tendency to stutter and jerkiness increases in the low-RPM and partial-load range."

It is possible to reduce the fuel injection amount without making mechanical changes to the ESP (electronic fuel pump) within certain limits using VAG-COM. Try using the search function and entering "diy-ruckelabhilfe" (DIY anti-misfire solution). It describes how to mechanically reduce the fuel injection amount. However, I strongly advise you to only perform the mechanical adjustment of the ESP setting (i.e., moving the pump's upper part) with VAG-COM as a verification.

I just stopped by the VW dealership for a short visit, and they even took the car for a test drive.

I won't comment here on their expertise regarding issues like juddering, but I did ask them how much it would cost to have them install their 'DIY judder fix' using their VAGCOM system.
The expert said it would take at least half an hour (which would cost approximately 80 euros).

How do you do that? Can't you just obtain the software and connect the car to a laptop, or is it cheaper to use the Bosch service?


It would be great if you could share your experiences with this, as I'm now almost 100% sure that the shaking I'm experiencing is related to a misadjusted fuel flow meter, and I don't want to spend much more money on my car (which has 340,000 km).


Thank you, Basti!

Basti911 wrote:

How do you do that? Can't you just get the software and connect the car to a laptop

?
Yes, of course, the software is available as shareware (which is sufficient for that purpose) and can even be downloaded for free.
Then you'll also need an adapter - see, for example, a technical article on diagnostics.

Quote:

because I am now almost 100% certain that the jerking I am experiencing is related to a misadjusted fuel metering unit, and I don't want to invest much more money in my car (340,000 km)!!!

Your problems sound like they stem from an MSW that was modified for tuning purposes. In that case, the adjustment range may not be sufficient to "fix" it.

The car has not been tuned using a chip, a tuning box, or manual adjustments on the engine control unit (ECU).

Do you think that an adjustment via an interface could at least partially correct a quantity setting that has shifted over time?
The VAG employee was quite certain that it should be possible.

I faintly recall that during the last diagnostic check, the fuel injection amounts were within the normal range (even though it was already jerking), or are other parameters being adjusted?

Is the structure of this shareware program the same as the original VAG program?
Is setting up and using your own 'VAGCOM' system a major undertaking?


Thank you, BASTI!

Hi,

With my 0.81 VAG-Com, no adaptation was possible in the shareware version. I don't know how that is with newer versions.

Best regards, Rainer.

Rainer K. wrote:

With my 0.81 VAG-Com, the shareware version did not include any adaptation options.

I'm not sure how that is with newer versions.
Hi Rainer,

That will probably be the same .

However, even with shareware, it's possible to check whether the apparent amount of LL (likely referring to a specific quantity or value) is too high.