Audi A4 B7: Idle Issues & Injector Problems?

Hello,

I drive an Audi A4 B7 with a 2.5 TDI engine (MKB: BDG), and it has 115,000 km on the odometer.
Now, in the mornings, I'm having a problem where it doesn't want to start properly.
It's rumbling and kicking up a cloud of dust behind it, really speeding along.
After a few seconds, it starts running better, but it still doesn't run smoothly.

This manifests as shaking inside the vehicle, and sometimes it struggles to accelerate properly. However, it can reach its top speed.
At a water temperature of 90°C, the engine vibrates and idles more roughly than when it's cold. However, the RPM is also higher immediately after starting.

Sometimes I have a problem where, after the engine has warmed up and I turn it off, if I try to start it again after, say, 2 hours, it takes a long time of cranking before it starts.

A new VP44 pump was installed 4,000 kilometers ago. The previous one was mechanically defective; something had become stuck or corroded.
Could the fuel injectors have been damaged due to the defect at that time?


I've now purchased VCDS and have already started logging some data.
Adjust the temperature based on the mode of transportation and travel conditions.
The first file is MWB 13.14 immediately after the start.


What do you think about this? How should we proceed from here, or should I change the way I'm logging things?

Sincerely,

Steffen.

Please enter the VCDS data in your user profile!

I will do it later.
Unfortunately, I just broke my Windows 7 installation.

Okay, the serial number has been entered.

I just performed the initial setup for the MWB4 again and obtained the following values with a warm engine:

Injection start: early, between 14.2 and 15 degrees before top dead center (BTDC).
Injection start late: -3.2 to -3.6 degrees crank angle before top dead center.

Shouldn't the start of injection for late combustion be in the range of 0-4 degrees?
Is something set up incorrectly here?


Sure, here is the translation of the text from German to English:

"Best regards," or "Sincerely,"

That's fine. / That's okay.

Okay, but what should I do next?
The idle speed values are not ideal, especially after starting the engine.
The blue smoke and uneven, rough idling after starting are concerning.
Should I have the nozzles cleaned, or should I collect some more data first?

What else I wanted to know: It's 10°C outside today, and the coolant temperature was 9.5°C according to the vcds.
He preheated for about 4 seconds; is that normal?
I actually thought that preheating wouldn't be necessary at such high temperatures.

The starting condition for cylinder 5 doesn't look good (relatively high amount). It's likely that the injectors are faulty.

Best regards, Rainer.

Hmm, I thought so too...
After starting, it briefly emits blue smoke and runs poorly.
When I perform the initial setup procedure (MWB4) after starting it up, it still produces a lot of blue smoke, either early or late in the process. Once it's warmed up, there is no more visible smoke.
Okay, so I guess I'll have to look into getting some new nozzles...

Short feedback.
We have now replaced the timing belt and also removed and tested the injectors on the left bank.
They all opened at a pressure greater than 200 bar and actually produced a nice spray pattern.
What I've noticed is that the exhaust fumes from the car are irritating my eyes quite a bit, and my tailpipes are very black.
In other V6 TDI engines, they are usually still in relatively good condition.

He probably starts relatively quickly, but he always emits a nice puff of smoke in the mornings.
"I've noticed that when the temperature is between 6-10°C, if the engine has been sitting for 2-3 hours after being at operating temperature, it will start after a few seconds of cranking, but the tachometer needle fluctuates rapidly between 1000 and 1200 RPM."
You can also hear that noise coming from the front of the engine compartment.

After a few seconds, everything is back to normal.

It's strange that when I've driven 35 km to work and want to leave after 2 hours, I have to pre-glow and then crank the engine for longer than during a cold start in -5°C.

What's the purpose of pre-injecting the nozzles?
According to the documents my acquaintance had, it stated that only the first stage could be tested.
Could the nozzles actually be damaged?

Can the dynamic settings of the VP44 only be measured using a dial gauge?
Could a faulty setting cause such symptoms?

Maybe someone can still help somehow .

Sincerely,

Steffen.

Have you also checked the camshafts and rocker arms? The V6 engines unfortunately have problems with those components.

The exhaust pipes are black on all TDI models without a factory-installed Diesel Particulate Filter (DPF).

They looked brand new. No signs of sanding were visible...
I didn't notice anything else unusual about the rocker arms.
If something were broken, wouldn't the car be running poorly all the time?
Perhaps my new pump isn't quite working properly either. But if that were the case, wouldn't I be seeing poor idle readings on individual cylinders?

Could the fluctuating RPM in the range of 1000-1200 be caused by a faulty injector?
It fluctuated between 1000 and 1200 revolutions per minute every half second.
Could a point machine (Mengenstellwerk) of the type VP cause this issue?

One more question.
Do negative values in the idle speed control indicate that less fuel is being injected, or that the cylinder is weaker than cylinder 3 and therefore receives more fuel injection?

This morning at 6:00 AM, I read a few values again before starting.
Outside, the temperature was approximately 2°C, and my G62 sensor indicated that the coolant temperature was 9.9°C, the oil was 8.8°C, and I believe the fuel was around 12°C.
Are such deviations already critical?
The car had been parked since 6:00 PM the previous day.

Hello,

Negative values in the idle speed control system indicate that the corresponding cylinder is producing more power than the others, and therefore the injection quantity is reduced. Conversely, positive values indicate the opposite.

Best regards, Rainer.

So, I don't have to worry now that the 5-cylinder engine might have too little compression, right?
I think I'm going to disassemble the device again and swap out the nozzle from the 5th unit with a different one to see if the problem follows it.

Is everything okay with the temperatures?

Das war heute morgen, Außentemp 2,5°C lt. Fis:

Address 01: Engine Control Module (8E0 907 401 AF)

06:29:05 Block 012: Preheating system.
01010000 Binary value.
3.76 seconds - Preheat time.
11.86 V Supply voltage
9.9°C Coolant temperature (G62)


Best regards, Steffen.

Hi again,

So, if all five cylinders that are within a reasonable range start drifting towards the negative side, is cylinder number 2 significantly on the positive side?

It's not possible to reduce the injection amount for all cylinders, is it?
Does the total injection volume suffice?
Are you pushing it to the limit right now?

In this log entry, for example: