T4 Syncro - 2.5 TDI ACV: Leistungsmangel | Posts 16+

06-08-2010, 11:51 Subject:

Octavia_4x4 wrote:

The problem likely lies in the fact that neither the LD valve nor the EGR valve are being activated, but they are technically okay.

Where do you know that from?

06-08-2010, 20:18 Subject:

because a brand new valve was tested in each socket, and neither of them is being activated.

Furthermore, as I mentioned earlier, it has been checked:

- Error memory >> Empty.
- Valve disconnected >> Error entry.

Since the valves are mass-controlled, I assume the mass airflow sensor (MAF) is working correctly, but there's no positive voltage supply. I haven't measured the voltage yet, but I will.

Based on the above facts, I conclude that the problem must be related to the positive voltage supply; according to the wiring diagram, both the AGR and the N75 are connected to the same positive voltage circuit.

06-08-2010, 20:50 Subject:

"What is your idle air mass reading? If it's not being metered, that means the EGR is off, which would be around 500mg per stroke."

14-08-2010, 18:00 Subject:

Okay,

"I was on vacation, so a friend of mine who runs a workshop checked the car. The valve timing etc. is now all correct, but it seems the wastegate on the turbo is broken, so it's likely a turbo failure... Well, it's not uncommon after 290,000 km, but it's annoying. I doubt it will be repaired on such an old car."

14-08-2010, 18:03 Subject:

Octavia_4x4 wrote:

...and I don't think it will be fixed anymore, with that old car.

Hm, are you seriously going to scrap a 1999 T4 because of 500€ worth of damage?

14-08-2010, 18:35 Subject:

No, nonsense.

It's not mine... it works perfectly fine, just with a little less power... I'll send you a private message right away

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15-08-2010, 12:04 Subject:

Hi, the ACV (automatic clutch valve) can last for over 290,000 km. Secure the bracket for the vacuum sensor on the turbocharger, replace the screws for the bracket, and check if the bracket is bent.

15-08-2010, 15:55 Subject:

Hmm, that's an interesting idea...

I'll take a picture this week, and then you can tell me if it looks normal.

Plan B is still the DPF, but hopefully that's not the problem...

15-08-2010, 16:29 Subject:

Octavia_4x4 wrote:

Plan B is also still the DPF, not that it's the problem...

As I said before: Try taking it out!

15-08-2010, 21:14 Subject:

Okay, I understand. Please provide the text you would like me to translate from German to English.

This is the current plan, and I'm also going to take another look at the wastegate valve... it's also producing a lot of black smoke, which means it's probably not getting enough air.

It could be due to a faulty charger or the cork, because if that's the case, the turbo won't be able to operate properly. Everything else has already been checked.

Ah, yes, the boost pressure is 0.2 bar below the target.

15-08-2010, 21:35 Subject:

Quote:

Oh yeah, the boost pressure is 0.2 bar below the target.

Air intake leak, faulty EGR valve, or wastegate not closing properly.

Best regards, Rainer.

16-08-2010, 8:01 Subject:

Hello Rainer,

Turbocharger air leak >> already ruled out.
AGR >> expanded, checked, okay.

Therefore, the turbocharger mentioned earlier is considered "defective," specifically its wastegate.

Edit: *Opening a bottle of sparkling wine* That was just the 1000th post here

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05-10-2010, 21:20 Subject:

Let me take a look. The LD (likely referring to a sensor or component) is working again. The wastegate was slightly stuck... repeatedly moving it seems to have resolved the problem, at least for now.

New theory: Our workshop has always used standard 10W40 oil, not low-ash oil with DPF approval. The filter is probably slightly clogged, and we wanted to try to clean it out and then use good DPF-approved oil.

I hope that solves the problem. Oh, and it always had the filter designed for dusty environments installed – it's thicker and has a foam pad underneath, which provides extra protection.

05-10-2010, 22:32 Subject:

Quote:

new theory: our workshop has always used standard 10W40 oil, not low ash oil with DPF approval. The filter is probably slightly clogged, and we wanted to clean it out and then fill it with good DPF oil...

Ascharmes oil doesn't add anything as long as there's no soot. Normally, ACV engines consume very little oil, even with high mileage.

We also have a vehicle with an ACV where a DPF was retrofitted at 460,000 km. Today, it has over 600,000 km and has always used only standard 10W-40 oil, and has had absolutely no problems from the beginning!