4B AKE - Nozzle defect?

Hi,

I have a 4B model from 2003 with an AKE engine, which belongs to a friend.
It occasionally jerks and starts making a very noticeable knocking sound.

I once looked at MWB 13+14:

13: -0.39 mg/H -0.23 mg/H
14: -2.50mg/H , 25mg/H 0.23mg/H
Those were the readings while he was constantly complaining while driving.

It started with the following values: -1.96 mg/H, -0.70 mg/H, -0.62 mg/H (MWB 14).
-1.72 mg/H -0.62 mg/H -0.62 mg/H (MWB 14)

It seems that cylinder 6 is the most prominent issue, or am I mistaken?
Should the nozzle be replaced? Or what else could it be?

Sometimes, it has trouble starting, and then for a second or two, it seems like it's not getting any fuel, and then it runs again.

Does the idle speed control system operate while the vehicle is in motion? I thought it only worked in neutral.

The start of fuel injection and valve timing can also cause a rough engine idle, but I think you're already aware of that...

"Sometimes, it doesn't respond to the accelerator very well, which you can see in the turbo pressure and mass airflow sensor readings." That could also refer to AGR or VTG.

The values could be caused by faulty compression (e.g., coolant leaking into this cylinder) or the nozzle. The values are not okay.

Personally, I would recommend having the injectors cleaned first. Then you can see if the injector is okay or not. After that, you can inspect the glow plugs as well. If everything seems okay, then proceed with a compression test.

Later, you can log the values to see if the problem with the gas intake persists.

Good luck!

I logged some values, maybe we can see something interesting in them.
What's noticeable is that the MWB 14 has completely dropped into the negative range, and it's also making a significantly different running noise!

Or were other values perhaps more suitable?

I once performed a basic adjustment of the MWB 4 - 15v. Should the OT (output transformer) voltage be adjusted to 15v, or should it be adjusted to 0.5 after the OT, alternating between the two?

vagtuning wrote:

I once performed a basic adjustment, MWB 4, with a setting of 15v. Should OT (output transformer) be adjusted to 15v or 0.5 after OT, alternating between the two?!

Regarding your logs, there are specialists here who I'd prefer to consult first.

The engine alternates between early and late timing, as intended. The tolerance values are estimates (but are supposedly mentioned somewhere in the forum): Early <-14, Late between +2 and -2. Therefore, it's probably okay.

You checked the dynamic start time correctly, so you did it right. V6 is not compatible with the TDI graph.

The idle speed regulation should be between +/- 2, so it's definitely outside the tolerance. I would address that quickly. In my opinion, the best and cheapest solution is to remove the injectors for inspection and examine the air intake manifold. After that, you can analyze the new logs. I suspect that a faulty injector or a lack of compression might also be reflected in the logs. Therefore, I will start by addressing the idle speed control.

Okay, I would start with the compression test first, as that's probably the easiest. (Just warm up the engine a bit, remove one glow plug at a time, and insert the tester... but be sure to disconnect the ESP so the engine doesn't start!)

After that, I would have the nozzles cleaned.

cksIT wrote:

So, I would start with the compression test first.

"Few people have a device like that (?). Then it's probably also a matter of taking the measurements correctly. I've read quite a bit about how the workshops messed things up." Besides, I wouldn't have blown out the candles voluntarily.

If the compression is indeed lower on one cylinder, the first thing to check is the exhaust valve, as it could be the cause and the easiest solution. If it's not the compression, then the nozzles also need to be removed.

In my opinion, regardless of what happens, the cylinder head cover needs to be removed, the NW (presumably referring to a specific component) needs to be inspected, and the injectors need to be taken out. Driving with faulty injectors can ruin an engine. That's why I suggested doing this before performing a compression test. If you see something like a broken valve or a severely worn valve seat, you can skip the compression test.

Good luck, fellow V6 sufferers!

Okay, let's try releasing the pressure and see what happens. One nozzle opened at 180 bar, but nozzles 3 and 4 got stuck. If you pump them forcefully about 10 times, they sometimes produce a decent spray pattern, but then after 2 minutes, they start to drip.
What was surprising was that, according to Bosch, cylinder 6 wasn't causing any problems – it was even checked specifically. But there was nothing wrong – the image was great, and the pressure was also perfect.

Okay, the loud hammering noise is gone now - the value of cylinder 6 is now hovering around 0.11, while the rest are in the 0.xx range. Funny engine

vagtuning wrote:

Funny engine

Okay, here's the translation:

"Exactly!" The V6 engine has something special .

Have you replaced the nozzles yet? What about the NW? Run over, or spared (so far)?

Camshafts are absolutely excellent - there are absolutely no signs of wear visible, felt, or measurable.
Yes, the nozzles have been replaced.

vagtuning wrote:

The camshafts are absolutely top-notch - there are absolutely no signs of wear visible, felt, or measurable.

Congratulations, would you like to trade?

The values are strange, I have the same difference for all of them, even though all the camshafts have worn .