A4 B6 2,5 TDI 180 Ps BAU, Leistungsloch unter ca 2800 U/min | Posts 48+

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Hi,

What do the camshafts and rocker arms/lifters look like?

It's not uncommon for the rocker arms to simply fall out due to certain wear. They then end up inside the cylinder head, the cam lobe rotates freely, and one or more valves remain closed. However, since each cylinder has two intake and exhaust valves, this problem often only manifests as a lack of power.
Investing in two new valve cover gaskets and occasionally taking a look under the hood provides peace of mind and costs well under €400.

Regards, Mpire.

Okay, thank you. Therefore, only the parking flap remains, which, in my case, is already operated electrically.


But something else. Today, I detached the hose from the pressure sensor again while the engine was running. When putting it back on, the first 2/3 tightened quickly, and the last 1/3 tightened very slowly . Afterwards, I checked it again using VCDS, and here, the VTG is shown to be tightening properly throughout the entire range *tilt*.
I just took the pressure sensor off again, and the VTG (variable torque generator) itself is a common part...
How's it going?

Quote:

Hello, What do the camshafts and rocker arms/lifters look like? It's not uncommon for the rocker arms to simply fall out due to certain wear. They then end up inside the cylinder head, the cam lobe rotates freely, and one or more valves remain closed. However, since each cylinder has two intake and exhaust valves, this problem often only manifests as a lack of power. Investing in two new valve cover gaskets and occasionally taking a look under the hood provides peace of mind and costs well under €400.

Oh, that overlapped.

.... I've also been told that, it's on my list...

Quote:

But something else. Today, I disconnected the hose from the pressure sensor again while the engine was running. When I reconnected it, the first two-thirds tightened quickly, but the last third tightened very slowly. Afterwards, I checked it again using VCDS, and it showed that the VTG (Variable Turbine Geometry) was tightening correctly throughout the entire range. I just took the pressure sensor off again, and the VTG (variable torque generator) itself is a common part... How's it going???

Does anyone else have a brilliant idea about this?

Okay, I'm just going to assume that something might be wrong somewhere in the vacuum system connected to the pressure sensor.
I would gradually start replacing the hoses and valves now.

Quote:

one more question. The vacuum hose that runs over the engine and later branches off to the AGR valve via a T-connector, where does it continue to?

It seems to lead to the vacuum reservoir.

[Edit Admin: Please be mindful of copyright regarding images!]

So, I temporarily replaced the valves with new ones and checked all the hoses. The vacuum chamber is also in good condition.
It's quite logical that the VTG (vacuum transfer gripper) only engages slowly after the hose is disconnected, as the vacuum needs to be re-established within the container first.

Okay, I'm going to focus on the fuel injection quantity deviations now, which have mysteriously increased.

Cylinder 6 Cylinder 4 Cylinder 5 Cylinder 3 Cylinder 1
mg/H mg/H mg/H mg/H mg/H
-2.43 -1.80 -4.31 -2.98 0.16
-2.43 -1.88 -4.31 -2.98 0.16
-2.43 -1.80 -4.31 -2.90 0.24
-2.43 -1.88 -4.31 -2.90 0.16
-2.43 -1.80 -4.31 -2.90 0.24
-2.43 -1.88 -4.31 -2.98 0.24
-2.43 -1.88 -4.31 -2.98 0.16
-2.43 -1.88 -4.31 -2.90 0.24
-2.43 -1.88 -4.31 -2.90 0.24
-2.43 -1.88 -4.31 -2.90 0.24
-2.43 -1.88 -4.31 -2.90 0.24
-2.43 -1.88 -4.31 -2.90 0.24
-2.43 -1.88 -4.31 -2.90 0.24
-2.35 -1.80 -4.31 -2.90 0.24
-2.43 -1.88 -4.31 -2.90 0.24
-2.43 -1.88 -4.31 -2.98 0.24
-2.51 -1.96 -4.31 -3.06 0.24
-2.59 -1.96 -4.31 -3.06 0.24
-2.59 -1.96 -4.39 -3.14 0.24

Okay, let's swap the nozzle stems now. If nothing changes, then things probably aren't looking good?

Could it really be that I have compression loss on 4 cylinders?
As far as I'm concerned, the head gasket might be leaking on the bank, but cylinder 3 is also affected... so it could also be the head gasket or the piston rings... or something else.
It would be quite a strange coincidence, though, wouldn't it?
Especially since I'm not experiencing any water or oil loss, and the car isn't smoking.

What exactly do these values represent? Is it about the measured deviations (in which case it would mean that too little fuel is being injected, or that the affected cylinder is not developing the power it should)? Or are they the correction values, meaning that an instruction is given to inject less fuel?

Was was bei idle speed, with the engine warm?

Generally, a downward correction means that the cylinder in question requires less fuel to maintain a consistent speed, which indicates that it is performing better than the others.
"It appears that four cylinders are significantly underperforming. What you're not seeing is the reference cylinder, number 2, and it doesn't seem to be running well." Since the ESD (Electrostatic Discharge) component is located near the needle injector in this case, you cannot simply swap it with a different one.

Since the search has already covered various aspects of the (engine) system, I'll ask about the valve timing (intake and exhaust, the latter being initially adjusted using the timing checker).
hg
Herbert.

Hi Herbert, yep, warm and idling.
The default values are 14.8 and 2.6.
You're right, I hadn't thought about the possibility that the reference cylinder might have some play.

You can certainly do a lot with the values, but it's difficult if you don't know the target values.
How about the TDI graph and a Screenshot?

"A problem with a cylinder can indicate issues with compression, or it could be related to the fuel injector."

hg
Herbert.

Hi,

The target values for "Spät" are between 0° and 4°, so it looks good.
I can't find a target value for the early timing, and it's not displayed in the TDI graph either.

"Screenshot" was the suggestion.
Call up the TDI graph in its default settings, select the correct engine, and then, for example, use the "Win Druck" function to display the image in Word or a similar program.
hg
Herbert.

Hello Herbert,

I have the values from the TDI graph. My current value is centered at 2.6° late, so we don't need a Screenshot anymore.
For early morning hours, no target values are specified; the graph only indicates "waiting for late."

Hey guys,

I'm going to replace the nozzles now and have a few questions about replacing the valve cover gaskets.

- Are the seals for both benches really the same?
- At the critical points, sealant (I will be using Elring Dirko 300) needs to be applied. I watched the following video for instructions:

https://www.youtube.com/watch?v=lz5ZISgHPMw

Are they applying too much filling material? It seems like it all seeps through, and in the worst-case scenario, it could end up in the head, where it could potentially detach.

- Can I drive directly after the replacement, or should the material dry for 24 hours first?

Thank you.

Best regards from Tobi.

Replace the sealing rings where the nozzles pass through; they are available for purchase. Otherwise, it will leak oil like it did for me. I've already got some replacements ready for next time.