Vibrations

Before I start, I've already searched on Google and looked under "search."

I drive an A4 1.9 TDI with 81 kW, manufactured in 1997. (zu2.0588, zu3.628)
When the temperatures are mild, my car vibrates strongly when idling. This is noticeable in the steering wheel, which vibrates. The interior of the car also rumbles.
It's almost gone when it's cold or very hot.
It starts well, has no rust, the performance is excellent, and the fuel consumption is normal.

"At VW, they fiddled around with a laptop for two hours, disconnected various sensors, and couldn't find any error."

I've already run it without the pulley on the crankshaft, and of course, also without the belt. The problem was still there.
The engine mounts/dampers are also new. (75 euros)
The dual-mass flywheel is also new. (450 euros)
The diesel pump was re-sealed and adjusted by Bosch. (150 euros)
I checked the fuel injectors, and they were all good (free of charge).

I'm a car mechanic myself, and I'm about to have a complete breakdown!

Hello!

The 81kW TDI engine in an A4 would be the AFN, correct?

What software version is your MSG running? Is there a possibility of an update? While we usually only hear about such problems with PDs (Personal Digital Assistants), it's possible that there are also problematic software versions with VPs (Virtual Private Servers).

Was your exhaust system also checked for stress or strain?

Does the shaking occur when the vehicle is idling while stationary, and/or when it is moving?

What is your carburetor jetting setting (more lean or rich, see MWB 1)?

Regards,
Alex.

yes, of course.
I can't say anything about the software, and I don't know if it's possible to update it. They tested it for two hours at VW, and they really put it through its paces.
The exhaust is fine, and the rubber hoses are okay and not tightly connected.
The shaking only occurs when the engine is idling.
The pump is precisely at the average setting and was also adjusted using a tester. It was also sealed at the mass airflow sensor and positioned opposite the timing belt.

"The strange thing is that the engine runs well overall, but depending on the outside temperature, vibrations appear when the car is stationary. At temperatures below freezing, the vibrations are barely noticeable. And Volkswagen has given up on trying to fix it. I've even run the car without the mass airflow sensor because of the intake air temperature sensor, but it still vibrated... There was an error code, which I also cleared."

I'm speechless... I'm seriously considering selling it in the winter.

I'm speechless... I'm about to sell it in the winter...

Nana, not so fast!

Do you have VCDS (VAG-COM), and can you query the idle speed correction (idle speed control) for each individual cylinder? What does the reading look like for each cylinder when the engine is misfiring?

The intake path is sealed. I removed the intake manifold to check if the gasket is still in good condition.

Transmission support (if applicable), okay?

I once borrowed a VAGCOM device and downloaded the standard values from the internet. And everything was within the normal range. I can't really comment on the idle speed correction (idle stabilization) right now. I'll borrow a VAG-COM tool next week and take a look.

I'm just thinking that if the intake manifold was sealing properly, wouldn't I have felt something during the drive?

The gearbox and suspension are also in top condition. I had a look at them when I removed the flywheel... ugh...

That's part of the AFN!

You're not the only one. I've been dealing with this problem for three summers now.

Besides the €500 diagnostic costs, I have already replaced the engine mounts and all the injectors.

I'm just dealing with it now, since it's really just a matter of lacking some comforts.

Regards,

Manuel.

Okay... It's crazy that we can't figure out the problem and what's causing it.
Someone must have had that removed at some point.

There must be a reason for it. Especially since he only does it in mild temperatures.
It doesn't work in freezing temperatures, but it works better in extreme heat.
He also tends to be a bit sluggish when it's warm.

Here's a list of what other people have exchanged for the same problem:

Air mass sensor.
Timing belt.
Clutch.
ZMS
Fuel injection pump.
Engine mounts.
Nozzles.
Electrical sensors.
Exhaust hangers.
This could be listed indefinitely.

And you can look forward to it. This is just the beginning. It's getting worse, to the point where it happens regardless of the temperature.

It has happened twice already that my car started vibrating, but then it was quiet again at the next traffic light. For that, then on the following, not, etc., etc., etc.

When I brake slowly, he usually stays calm. If I brake hard, it vibrates.

If you find the error, please let us know. I will no longer pay for expensive repair installments that almost exceed the value of the car.

Regards,

Manuel.

Hmm... it kind of reminds me of "idling" and the search function...

Take a look at the actual fuel injection quantity value. If it's fluctuating erratically in the event of a fault, then you'll know what's going on.

Best regards, Rainer.

Okay, so I borrowed a VAGCOM laptop and did some measurements.

block 0, line 4, injection amount 27 (should be 11...45)
Line 8, intake air temperature: 160 (target: 50...182)

Block 1, line 2, injection amount: 5.4 (target: 2.2...9)
Line 3, adjustment slider: 1.72 (target: 1.46...1.9)

block 3, line 4, key press: 59.8 (target: 10...90)

block 4, line 2, fuel injection start should be 1.3 (target: 1.3 degrees before top dead center).
line 3, injection start is 1.5 (should be 2° BTDC, 4° ATDC).
line 4, key input: 77.7 (target: 95)

block 13, line 1, 0.05 (No target value)
line 2, -0.38 (No setpoint)
line 3, 0.40 (No setpoint)


What are these data supposed to tell me?
I think I'm going to adjust the fuel injection timing slightly to ensure it falls within the specified range.
I got the required data from this site. http://www.dieselschrauber.de/Solldaten_Main.html

and what should I do with block 13? It's a complete mess... *sigh*... *slurring words*.

block 0, line 4, injection amount: 27.
8, suction pipe temperature: 160.
Block 1, line 2, injection amount: 5.4.
3, throttle slide 1.72
block 3, line 4, key press. 59.8
block 4, line 2, injection start should be 1.3.
3, the start of injection is 1.5.
4, touch-sensitive 77.7
block 13, line 1, 0.05
2, -0.38
3, 0.40


What are these data supposed to tell me?


For your benefit, I would provide meaningful data. Usually, you can only play the lottery with such information. Sure, here's the translation:

'Please be so kind...'

Okay, I've made some changes to make it clearer. The units are not specified, and I just want to know if anyone can identify any errors based on the data.

The vibration is always there when it's warm outside.

"It also vibrates in the morning when I start it for the first time, especially if it's warm outside. Sometimes it doesn't vibrate at all at the beginning, but then after driving for a short distance, it starts vibrating and continues to vibrate all day."

bluhminga wrote:

block 13, line 1, 0.05 (No target value). line 2, -0.38 (No setpoint) line 3, 0.40 (No setpoint) Bitte gib den Text an, den du übersetzt haben möchtest. and what should I do with block 13, it's quite a mess....... sigh... hiccup...

It doesn't look that bad, considering that other engines have a tolerance of +/- 2.0 specified.
Or are the values constantly fluctuating?

You could try adjusting the LL speed -> Technical article about adaptation channels.

Alternatively, you can verschandeln the pump according to the instructions (-> see another article for details), or perhaps you're experiencing a variation of partial load surging that is manifesting itself in the low range...

Or are the values constantly going up and down? No, they are stable when standing still.
During the ride, the values change, but not so much that they go up or down. No, I would say they are stable.

A type of partial load rattling that is noticeable in the LL (likely referring to a specific system or component). What is it?

The pump was cleaned, and a new set of seals was installed.

bluhminga wrote:

A type of partial load judder that is noticeable in the LL (low load). . . what is that?

Use the search function "judder" and take a lot of time to read.

Quote:

The pump was cleaned and a new seal kit was installed......

With "cleaning," I meant this:
Okay, I'm ready. Please provide the German text you want me to translate.