A4 B6 2,5 TDI 180 Ps BAU, Leistungsloch unter ca 2800 U/min | Posts 32+

Quote:

As far as I can see, the boost pressure is lagging quite a bit

and isn't regulating properly.

It actually looks pretty good.

Best regards, Rainer.

Then I can probably give up searching for vacuum leaks, right?

I once looked at the control unit, and it looks a bit messy inside the casing... especially the design with the hose connections and the cut-off cables, which I find quite adventurous.
The component doesn't look like it has been soldered, does it?

Hey guys,

Sorry to bother you, but I'm really frustrated that the car isn't running properly.

Could it be that something was actually tampered with in the engine control unit (ECU)? Okay, the part number should be correct, the MKB BDH part number is 8E0 907 401 N (I had made a mistake earlier...).
I wonder why a chip has to be desoldered and resoldered during an engine control unit replacement. It should only require training on WFS, right?
Should I just get a different engine control unit (ECU)?

Hello.

Quote:

I wonder why it's necessary to solder a chip when replacing the engine control unit. It should only require training on WFS, right? Should I just get a different ECU?

Depending on the WFS generation, it may be easier to replace the 8-pin EEPROM than to modify the WFS itself.

If you can get a correct (complete VAG part number, including letters, must match) engine control unit with the original data set, preferably without WFS, it might be worth trying.
If it doesn't work out, you can always sell the equipment again.

Best regards, Rainer.

Hey Rainer,

Thank you for the feedback. Without WFS, it will probably be difficult. Is there a possibility of enabling WFS via VCDS, depending on the generation of the vehicle I have?
You can find those control units on eBay for around 40 euros.

What do you think about the variations in fuel injection amounts?

Cylinder 6 Cylinder 4 Cylinder 5 Cylinder 3 Cylinder 1
mg/H mg/H mg/H mg/H mg/H
-1.65 -1.02 -3.22 -2.67 0.16
-1.65 -0.94 -3.29 -2.75 0.08
-1.73 -1.02 -3.29 -2.75 0.16
-1.65 -1.02 -3.29 -2.75 0.08
-1.73 -1.10 -3.29 -2.75 0.08
-1.73 -1.10 -3.37 -2.75 0.08
-1.73 -1.10 -3.37 -2.75 0.08
-1.73 -1.10 -3.37 -2.75 0.08
-1.73 -1.02 -3.37 -2.75 0.08
-1.73 -1.10 -3.37 -2.75 0.16
-1.73 -1.10 -3.37 -2.75 0.08
-1.73 -1.10 -3.37 -2.75 0.08
-1.73 -1.10 -3.37 -2.75 0.16
-1.73 -1.18 -3.45 -2.75 0.08
-1.80 -1.10 -3.37 -2.82 0.08
-1.73 -1.10 -3.45 -2.82 0.08
-1.73 -1.10 -3.37 -2.82 0.16
-1.73 -1.02 -3.37 -2.75 0.16

Broken, faulty motor/ZK (glow plug) or nozzle holder combination, or poorly assembled and leaking.

ok, so, have you found any errors?

Nozzles would be the lesser of two evils; I was planning to have them replaced anyway.

What kind of engine or cylinder head defects could cause these deviations?

Cylinders 5 and 3 have the largest deviations. Since they are located on opposite cylinder banks, it seems likely that both cylinder heads are faulty.

He doesn't attract oil and/or water, at least.

Seriously, you're not planning to invest a four-digit sum into a car that's only worth 1500 euros, are you?

I own the counterpart, a Passat Variant 3BG 4-Motion with a BDH engine, and I have to say that after driving 5,000 km and having the vacuum system sealed beforehand, the car drives completely differently. My friend, who was the previous owner, drove it last week and didn't even recognize it.

"Before, the car was sluggish, especially at lower speeds, but now I can shift into sixth gear at 60 mph, and it pulls strongly."

Actually, no. A diesel injector overhaul for €400 is still an option.
If someone's head or something worse gets damaged, they just go to Eastern Europe.

I wouldn't even invest the 400 euros. First, focus on replacing the Peanut parts I mentioned earlier, and then properly test drive the car.

I will do it.
Could the variations in injection volumes not be related to problems in the vacuum system?

No, I don't think so, but it's also unlikely to be related to poor performance.

Quote:

The rubber grommet in the last photo, which passes through the partition to the water reservoir, has been the cause of vacuum problems in TDI engines on several occasions.

I just changed it, but nothing has changed.
Otherwise, I would simply proceed systematically and replace the valves and hoses one by one.

One more question. Where does the vacuum hose that runs over the engine and later branches off to the AGR valve via a T-connector continue?

Greetings.
Tobi.