TDI Engine: Nail/Knock Repair Guide

Hey everyone!

Now I've finally become a member of the diesel mechanic forum.
But let's briefly describe the problem.
I drive a Golf III GT TDI with 90 horsepower, model 1Z, manufactured in August 1994, and it has almost 252,000 kilometers on the odometer.
Ultimately, the LMM (likely referring to a mass airflow sensor) was replaced and the ESP (electronic stability program) was recalibrated. All injectors were replaced. The three smaller fuel injectors were rebuilt, and the NHG (likely referring to a high-pressure fuel pump) was replaced. After replacing the NHG, the knocking/pinging became significantly worse. I cleaned the LLK (likely referring to an intercooler) from the inside and checked all the hoses.
The exhaust system has no leaks.
'Since then, the TDI has been making a very bad knocking noise. It's actually normal for an old TDI when it's cold, but when it's warm, especially after I've really pushed it, the noise is bad. It's especially this knocking sound.'

Now I've read that pressure relief valves could also be a possible cause.
The cost at VW is 90 euros per piece...

Can someone offer me some help? This knocking sound is especially noticeable at idle, and it's really annoying! The engine is also running roughly.
AND the exhaust smell is quite like a tractor... like an old truck!
'The catalytic converter is out, and the AGR valve has been sealed! But I've had that truck smell before, even with the catalytic converter and AGR valve!'

Can you tell me something about when the injections start?

Have you ever checked it using VAGCOM?

If I let my TDI (which doesn't make any knocking noises even when cold) run through its entire cycle from start to finish, there are noticeable differences that can be heard.

I hope you didn't have the ESP adjusted *before* having the injectors replaced???

If so, adjust the ESP again, because the start of injection has likely shifted due to the new injectors opening correctly while the old ones are probably opening too early.

Did you happen to replace the 190 bar 1Z nozzles with 220 bar nozzles?
Re-list it now!

But above all -> measure first.

m;

First of all, thank you very much for your response.

The ESP (Electronic Stability Program) was not recalibrated after the injectors were replaced. Is it electronically controlled by the NHG (presumably a control unit)? Or not? The ESP had been calibrated before the injectors were replaced, and it was precisely adjusted to the center line using VAGCOM (a diagnostic tool).
I'm looking for someone in the Aachen/Cologne area (privately) who can recalibrate it for me. (I can only bring my TDI for this on weekends due to work.)
Consumption: 5.0 liters per 100 km. Top speed: 180 km/h.
and there's almost no smoke, only when starting.
Someone once told me that at higher speeds and higher RPMs, there's a smell of burning rubber. The car hardly uses any oil.
It seems I'm also going with ESP.

'What about... or?'

After replacing the injectors, it is necessary to recalibrate the ESP. Due to the different opening pressure of the new injectors, various aspects of the system will change.

'Ulf once beautifully described in a technical article how the soundscape changes when the nozzles are positioned slightly differently... have you read it?'

Otherwise, it's also quite possible that something went wrong during the nozzle regeneration process. Is the opening pressure correct?

What are you looking for right now? Help, or someone who can fix the car?

hello!
Well, I had the injectors refurbished and inspected by Bosch in Aachen.
During installation, I made sure that the nozzles were installed precisely in the center of their designated space. I have read the article.
The 190 Bar injectors have been installed, and I'm looking for someone who can listen to the engine and potentially help me with it.
Any help is welcome!!!

Hello,

"I also initially had a loud clicking noise from the nozzles after replacing them. Based on the article about alignment, I reinstalled the nozzles so that they have the same distance to the holders on the sides and the upper ends are pushed away from the print head. Since then, the clicking has been softer. Before, I had installed them "in the middle"."
We could arrange a listening comparison sometime.

FlatEric wrote:

Now I've read that pressure relief valves could also be a possible cause. The cost at VW is 90 euros per piece...

Forget the idea about the pressure relief valves. I replaced them, and it didn't do anything except create a hole in my wallet! (By the way, the ones from AFN also fit perfectly and are much cheaper.)

/Jan

MichaelJ, that would be great! Unfortunately, I don't know anyone in my area who also drives a Golf 3 TDI. Where and when could we meet up? I tried to center the injectors and keep the clearance the same on both sides. However, I have to say that the NHG injector was replaced later than the other three injectors. Since then, the knocking has gotten worse.

Jan, Besides the price, are there any other differences between the pressure relief valves? Is it because the AFN has a higher working pressure?

Okay, so I need to get the ESP (Electronic Stability Program) recalibrated after replacing the injectors, right? I'd like to have it done, but I just want to know if it's actually necessary. Because it was already calibrated before the injector replacement.


Regards,
Eric.

NO, the AFN has the same pressure ratings as the 1Z (190/300 bar).

Only the Euro 3 TDI models have 220 bar of pressure on the first stage.


Yes, you MUST have the ESP (Electronic Stability Program) recalibrated after making changes to the nozzles (e.g., replacing them with new or different ones).

If you have VAGCOM, you can check how much the injection timing is "off."

m;

Hello Dieselmartin!!

Thank you for the tip!
Unfortunately, I don't have a VAGCOM, so checking the ESP will be difficult.
I've been driving around like this for 3000 km already. Could it be harmful in the long run?
Adjusting the ESP with VAGCOM is almost child's play.
'However, I've also been experiencing that well-known issue of engine hesitation at low RPMs under partial load. It happens when I'm driving between 1200 and 1700 RPM. It's not too severe and doesn't happen all the time, but it occurs sporadically.'

best regards
Eric.

By the way, can anyone get me a hood/bonnet for a good price?

If you've already started, there's nothing you can do to change it now.

Let's get the ESP disabled as soon as possible, and that will be fine.

There are countless posts about stuttering, including a recent one suggesting that the ESP (Electronic Stability Program) can also be cleaned.

After that, however, it must be re-enabled .

m;

Hello Martin!

Do you know anyone in the forum who wants to earn some money privately and lives near Aachen/Cologne/Bonn and has experience with VAGCOM?

Hi.

Rainer K. used to offer something like that, but I don't know if he still does, and I'm not sure how far away he lives from you.

Write him a private message.

m,

Hi,

Cologne is quite far away... I'm located in the Nuremberg area.

Best regards, Rainer.

Hmm, unfortunately...
Is there anyone from North Rhine-Westphalia (NRW) here?
I'd rather not go to 'Lieben' and lose a lot of money.

Okay, I live in Bonn, but I also spend time in Stolberg, that's why my suggestion about the "test drive." I also have a VAG-COM.
Currently, I'm visiting friends in Thuringia, which is why I won't be able to check the forum again until Monday.