Subject: Erratic idle speed | Posts 16+

Bertil wrote:

Warm up the engine, then come to a stop. Shift the transmission into neutral and release the clutch; the engine will shake like an old tractor. Now, depress the clutch pedal and keep it pressed down (without engaging a gear). After a short moment, the engine will run very smoothly! For me, it looks more like there are problems with the clutch. When the clutch is disengaged, there is no vibration, but when the clutch is engaged, the problem occurs. It could also be due to software issues with the EDC.

Hi Bertil.

if you could try both options and had access to VAGCOM .

Try plugging in a laptop and logging the idle power management settings... maybe that will help us track down the cause of this issue.

I know this should have been handled internally within Volkswagen a long time ago. But after my experience with the small and large intercoolers on the AFN engine, I'm not really convinced anymore.
I'll send you a (at least possible) solution via email, presented on a silver platter (small container out, large container in, adjust the VTG rod, and that's it), and the response will be something like:
"Please be aware that this technical modification, among other things, will void our product liability coverage..."

Hello Bertil,

das ist sehr interessant. Vor allem deshalb, weil sich immer mehr zeigt, das es ne Menge Leute (nicht nur 96kW, auch 74kW UND 150 PS TDI) gibt, die diese Probleme haben. Wenn es aber nicht PD ist, sondern die Getriebe/Kupplung zB, ist die Frage, ob das dasselbe Problem bei den Motoren ist, denn der 100PS hat nicht dasselbe. Trotzdem ist es wichtig, diese Spuren peinlich genau zu verfolgen, um eben das festzustellen, ob es ein PD / Getriebe / Qualitäts oder sonst ein Problem ist. Klar scheint nur zu sein, daß VW wie immer die Motoren in diesem Zustand einfach verkauft. Das kennen wir auch schon. Mein AHF hatte ein ähnliches Problem, das aber nach Schwungradtausch weg war. Das ist ja dann ärgerlich aber ok. IcI would laugh my head off if there were any problems with pimples.They try their best, but they just can't manage it.
Ich hatte auch schon einmal die wohl etwas weit hergeholte Theorie, daß VW die Problemautos für den ausländischen Markt aussortiert (meiner ist ein Reimport), da ich bisher mit mehr Leuten Kontakt hatte, die eben iin England, Portugal etc wohnen, und hier in D gibts scheinbar entweder weniger Probleme, weniger Leute die es zugeben, oder weniger Leute die es merken. Ich gebe aber zu, das das etwas weit hergeholt ist. Vielleicht wird sich das noch zeigen. I definitely won't give up...

I'm looking forward to hearing what else you have to say.

Regards,
Thomas.

Hi Thomas,
Hi Ulf,

I left the VAG workshop this evening with a huge grin on my face: A customer actually came in complaining about "idling vibrations" on his PD TDI (I have no idea which car it was). I had to hide in the showroom so I wouldn't burst out laughing. The senior service advisor said to me, "Two of those in one day is a bit much..."
Laut seinen Aussagen gibt es von VW einen Lösungsansatz. Aber Hoffnung auf Besserung wollte er mir nicht machen!!! Die PD Elemente (Hersteller Bosch) haben scheinbar zu große Fertigungstoleranzen und die EDC schon eine ganze Menge ausregelt aber eben nicht alles (so die Erklärung in Kurzform). In ca. 10 Tagen sind die neuen PD Element da und die werden dann in mein Auto eingebaut. Ich gehe davon aus das es sich dabei um selektierte und aufeinander abgestimmte PD Elemente handelt (10 Tage ET Beschaffung ist für VW ungewöhnlich). MiThe EDC needs to be changed!

Unfortunately (or perhaps fortunately), I'm a new customer at this workshop, and the mechanics aren't as forthcoming as they were at other dealerships I've visited before. As a result, some technical details are being missed because they haven't been explained to me.

I will, if my laptop decides to cooperate again, take some measurements of the idle stabilization process.

Hello everyone!

I drive a 96 kW TDI engine in an A6 (engine code 'AWX') and haven't noticed any idle vibrations so far.
I'm noticing some jerking when accelerating. I might have more to say about it tomorrow.

My father has a Golf TDI with 74 kW that he's owned since March 2002, and it hasn't experienced any idling vibrations either.

Best regards, D., who is still following your issue with great interest.

Hello,

Is there anyone nearby (in 26871 Papenburg) who can use their computer and software to adjust the adaptation channels for me? I would be very grateful.

Thank you very much.

Best regards, Thomas.

Hello,

Yesterday, I took some measurements of the idle stabilization system. During this process, I noticed that it doesn't look anything like the one found in the 1Z engine.
When the engine is warm, it vibrates and the measured values fluctuate wildly. With the 1Z model, the values were almost constant.

There is a repair kit (4 PD elements, part number 038 198 073 A). Originally, PD elements with the ending "AN" were used, but now PD elements with the ending "AR" are being installed (according to my VAG dealer from the parts catalog!).
On November 11th, the new PD elements will be installed (Helau!!).


@Ulf:
This replacement part with AT PD elements costs €1606.60 (including VAT) and not €2200.

Bertil wrote:

When the car is warm, the engine shakes, and the readings fluctuate wildly. With the 1Z, the values were almost constant.

Hi Bertil.

"In my opinion, this supports the assumption that the idle speed control system is becoming unstable."

In my estimation, this issue could potentially be resolved by adjusting the software design to be less strict – essentially, by implementing a more lenient control logic – without needing to replace the power drive (PD) components.
Only, that would probably require a new engine control unit per car - the question then is whether that would be cheaper than a set of new injectors .

Quote:

This replacement unit with AT PD elements costs 1606.60 EUR (including VAT) and not 2200.00 EUR

.

Wow, what a progress .
Are those replacement parts?

ulf wrote:

... "In my opinion, this supports the assumption that the idle speed control system is becoming unstable." ...

I believe that too.

Quote:

... In my estimation, this issue could potentially be resolved by adjusting the software design to be less strict – essentially, by implementing a more lenient control logic – without needing to replace the power drive (PD) components. Only, that would probably require a new engine control unit per car - the question then is whether that would be cheaper than a set of new injectors . ...

According to the VAG uncle, the (excessive) manufacturing tolerances in the PD elements are supposedly responsible for this.
So, I don't care whether it's PD elements or EDC (which, by the way, should also be replaced ).

Quote:

... Wow, what a progress . Sind das dann Austauschteile?

AT = Exchange parts

I have the same vehicle, but I can't detect any unstable idle speed.
If you ever happen to be in Karlsruhe, we can compare notes! Best regards, Bernd.

Hi,
Okay, I work at Mercedes, and when I replace a fuel pump (on an Actros), I have to enter a number that's printed on the pump.
It might not work with every control unit, but it works wonders!
This input of the number should compensate for manufacturing tolerances and protect individual cylinders from overstressing.
Is there something similar at Volkswagen?
Best regards,
Kalle

Hi Kalle,

This means that the pump injectors in the Actros are subject to certain tolerances, which are grouped together, and the control unit is calibrated for these injectors.
This adjustment will then result in a better overall balance. However, this requires the corresponding software to be present in the control unit (ECU), and I don't know if that's possible with the VW ECU.

"Helau" is a traditional carnival greeting in some parts of Germany. There isn't a direct English translation that captures the same cultural meaning. You could say:

"Happy Carnival!"
"Greetings from Carnival season!"
"Cheers!" (in a festive context)
"Hello!" (if you just want a general greeting)

Today, the VAG mechanics replaced the PD elements!

Result:
It idles a bit smoother now, but it's still not as smooth as my 1Z!

Die Motorcharakteristik hat sich erheblich geändert. Das Drehmomentloch (und somit auch die Anfahrschäche) was vorher da war gibt es nicht mehr. Das langsame einregeln der Leistung (nach dem Schalten) auf einen maximalen Wert gibt es nicht mehr. Es ist jetzt alles fast wie beim 1Z. Gefühlsmäßig geht er schlechter wie vorher, aber an meinem Messberg war ich schneller (!!!!) und die Endgeschindikeit wird schneller erreicht. Das schwarze Wölkchen was ich nach dem Kaltstart immer hatte (und beim PD normal sein soll) ist nicht mehr aufgetreten. The combustion noise has become slightly more aggressive (similar to what was observed in the 1Z after the nozzle replacement).

Let's see how it goes from here...

Bertil wrote:

Today, the VAG mechanics replaced the PD elements! Result: Er läuft im Leerlauf etwas ruhiger aber immer noch nicht so rund wie mein 1Z!

Hi Bertil,

At the moment, it would still be interesting to know if you can intentionally disrupt the idle speed control under certain operating conditions, just like before.
Would you do another data logging sometime?

ulf wrote:

... At the moment, it would still be interesting to know if you can intentionally disrupt the idle speed control under certain operating conditions, as before. Macht Du bei Gelegenheit nochmal ein Datalogging?

Hi Ulf,

What do you mean by "Betriebszusände"?

The idle speed control is only active when the accelerator pedal is at 0% and the thrust cutoff function is disabled.

The values are jumping and fluctuating wildly.

Hello Bertil,

Has your ECU (Engine Control Unit) been replaced as well?

Hello Michael,

It should be replaced. However, the expert only talked about the PD elements.
I'm going to try and find out tonight if the ECU (Engine Control Unit) has been replaced.

What ECU (Engine Control Unit) number should I expect to find (stock/modified), or is there even any information available about modifications?