V6 TDI BDH: Slight vibration after DK change.

Hi everyone, this is my first post here today. Hoping for active participation

Vehicle: VW Passat 4motion, 2.5 V6, 6-speed, 132KW, 02/2004, km 349'973, Sales description 3B6 398, FIN: WVWZZZ3BZ4E27****

Here's the translation:

Problem: Approximately 4 weeks ago, the ML (presumably a vehicle model) started acting up, and the engine would rev like a kangaroo when accelerating. It was diagnosed and the AGR (presumably an emissions control system component) was replaced. The error was cleared, and the vehicle was driven for about 2 days. The problem then reappeared, and the DK (presumably a component related to intake valve control) was replaced (exact specification: intake valve drive). The error was cleared, and the vehicle was driven... but the problem returned, and everything was fine. However, something is now particularly bothering me. The engine is now jerking in every speed range and every gear, but only when the accelerator is held down or a constant speed is maintained. My initial suspicion was the electronic accelerator pedal, but even after activating the GRA (presumably a related system), the jerking persisted. It's very weak, but noticeable.
Before the replacement of AGR and DK, it wasn't there, but I suspect that the completely faulty DK somehow compensated, so that the shaking wasn't noticeable. The engine performance was also previously rather modest.
The advantage of these two repairs is this:
1.) The accelerator pedal doesn't need to be pressed as far as before.
2.) Very spontaneous throttle response and strong power output from 1200 RPM.
3.) Fuel consumption has decreased by 1.0 liter to 6.8, even during brisk driving.

Yesterday, I used the VCDS to check the measuring blocks and the differences in fuel injection amounts. They are not okay and range from -0.16 to mg/H. Is it now due to the nozzles or maybe the VP44?

Then I replaced the LF and KF, and measured again. Now a slightly different picture emerged. The values were now only between -0.08 and +0.93 mg/H.

However, during the test drive, it only remained a slight vibration. Nothing has changed. It is particularly annoying during city and/or country road driving. On the highway, I also notice it, but the faster I drive, the less noticeable it becomes.

Has anyone of you got any ideas, or have you experienced this problem before yourselves??

Info's would be appreciated.


Thank you for reading.

Hello,

If the vehicle only experiences jolting when maintaining speed in a straight line, but not when accelerating gently, there may be play in the engine mounts or drivetrain.

Best regards, Rainer

The injection quantity deviations (= idle speed control) only apply to the idle, not to load conditions. The values are only meaningful when the engine is warm. The measured values are fine.
Was wurde richtig entlüftet (nach dem Filterwechsel)?
hg
Herbert

Hi Rainer,

I also thought about this, but it wasn't there before the change. The engine also has a slight idle, and it's not constant either. It fluctuates between 719 and 696 RPM... According to the specified value, it should have an idle of at least 740 RPM. But this has nothing to do with the jerking. If I'm driving on a flat road with cruise control, for example, at 80 km/h, the drivetrain is under tension. If the engine pulls with constant power, it can't jerk, even if there's play in the drivetrain, because that would resolve as long as the engine pulls with the same power. In my opinion, it can only jerk due to throttle changes, and he probably has those, but internally, somewhere in the engine. Electronic faults probably don't exist; the fault memory is empty. I also cleaned the LMM yesterday, but there was no change. I also checked that all the clips were in the correct position and that the closures on the hoses were secure. Do you have any other suggestions? Or someone here on the forum?

Best regards,
Michi

Hello Herbert,

The engine has been sputtering in the same way before and after the filter changes. I performed the filter changes simply to rule out potential sources of error, just like I did with the air filter change. The diesel filter had not been replaced for approximately 70,000 km (previous owner).
First, fill the new filter with diesel, then use hose clamps to disconnect the inlet to the VP and the inlet from the tank. Then, disconnect the return line from the filter with the fuse. Remove the plastic part. Remove the old filter and install the new one, first put the plastic part back in, then insert the fuse, connect the inlet from the tank, and finally connect the inlet to the pump. Tighten everything securely and fix the filter in its holder. Start the engine and leave the bleed screw open until only verschandeln diesel comes out. Tighten the screw again. Can we also vent it electronically?

Best regards,
Michi

Is there a drain screw on the VP44? I thought that with that type of pump, you have to vent at the return using a helper pump, or with the feed pump (if there is one)?
hg
Herbert

No, the VP44 does not have a vent.

amishorty wrote:

The following problem: Approximately 4 weeks ago, the ML (presumably a motorcycle or vehicle) started making a noise, similar to a kangaroo revving its engine. Extracted and AGR replaced.

Hi,

what exactly was stored in memory, i.e. a) before replacing the AGR and b) before replacing the DK unit?

Hi Roger,

so bei b) weiß ich es noch genau: "Saugrohr valve control without function". This is probably not a surprise, as the part was replaced one year after the original date of manufacture, i.e. in 2005, and had therefore covered 250,000 km. Accordingly, it also appeared.
In part a), I am no longer entirely sure. At any rate, I had extracted the measurement blocks and performed a log-forward, unfortunately without saving. The deviations between the AGR target and actual values were enormous in every speed range. Because of this, I replaced the AGR valve. However, I had already performed a check with a wrench on the AGR valve before that.
However, there is something new regarding the shaking: This morning, I went shopping and discovered that the engine does not shake when it is cold or during the warm-up phase. Only when it has reached its proper operating temperature, i.e., after a short highway drive of over 20km, does it start to jerk slightly again when accelerating and also with the GRA.
I guess I'll have to keep looking around. Somewhere, there's just one small thing that's not okay.
If I have acquired new knowledge, I will contact you again.

Thank you all for your help.

Best regards,
Michi

Hello,

my assumption: due to the new components, he now has the ARF rate that he should have according to the characteristic curve. After the rest of the hardware has worn down accordingly (nozzles, pump, etc.), the jerking occurs.

Try running the ARF with a metal plate, or almost a full plate, and see if it still jerks.

Were the camshafts ever completely checked for wear?
So, nicht nur durch das Loch im Ventildeckel.
With worn camshafts, it also doesn't read the correct values anymore.

The camshafts have not yet been checked for wear. I will check them soon, as there is also a clicking noise on the left cylinder bank (driver's side), although only at idle (sometimes louder, sometimes quieter) and under partial load. However, there is no clicking noise when accelerating moderately, but only at full throttle. Suspect a faulty hydraulic valve that only builds up full pressure under full load.

What is the ARF rate exactly??? And can I read it out with the VCDS-Plus?

Thank you and best regards.

Michi

The wear and tear on the bearings is no longer an issue with this engine. If then the cams break.

Also, I also had issues with my AKN. As a countermeasure, I inserted a kind of restriction in the vacuum line. First, I used a long, pointed screw. Later, I also used a similarly pointed spark valve. This allowed the AGR to close normally, but open in a reduced capacity.

Hello,

vwSchrauber wrote:

Let's try running the ARF with a metal plate, or almost a full plate, and see if it still jerks.

Not a good idea. If the ARF is closed, the LMM indicates too much fresh air, and the DK closes. Then the engine gets neither fresh air nor exhaust gases and has difficulty breathing. One can hear this in the form of loud clicking due to the increased ignition delay.

Best regards, Uli

Quote:

This is not a good idea. If the ARF is closed, the LMM signals too much fresh air, and the DK shuts down. Then the engine neither gets fresh air nor exhaust gases and has difficulty breathing. One can hear this in the form of loud clicking due to the increased ignition delay.

He should not. Because the required fresh air mass according to He still gets the field, but the rest isn't being filled with exhaust.
The gas density in the cylinder will be slightly lower, because the inert gas is missing, but at least the lambda-dependent ignition delay does not fluctuate.

I once had a similar issue on a Touran that I borrowed from a friend's dealership for troubleshooting.
Approximately 150,000 km, used car warranty, and the customer is extremely angry because the mill rattled/squeaked so much, especially under load and at low speeds, that it even stalled sometimes.
They had already unsuccessfully replaced the engine control unit, throttle valve, ARF valve, and cylinder head wiring harness up to that point.

I've slightly adjusted the air mass in the critical range, and it's been running since then.

vwSchrauber wrote:

He should not. Because the required fresh air mass according to He still gets the field, but the rest isn't being filled with exhaust. The gas density in the cylinder will be slightly lower, because the inert gas is missing, but at least the lambda-dependent ignition delay does not fluctuate.

You are probably right, sorry. I confused it with that time I bridged the LMM with the famous diode on an AKN to get out of intersections somewhat safely using a company car. Then it sees "air mass too high" and closes the fresh air intake to achieve the AGR rate (I then just disconnected the DK linkage, and it ran properly ). Or does it still detect the high AGR because the air mass is also higher than it expects?! I don't know, just speculation. Fortunately, our AFNs don't care, so I can't verify it

Quote:

once had a similar issue on a Touran that I got from a friend's mechanic for troubleshooting. Approximately 150,000 km, used car warranty, and the customer is extremely angry because the mill rattled/squeaked so much, especially under load and at low speeds, that it even stalled sometimes. They had already unsuccessfully replaced the engine control unit, throttle valve, ARF valve, and cylinder head wiring harness up to that point. I've slightly adjusted the air mass in the critical range, and since then

has been running smoothly.



Best regards, Uli