TDI Problems? Get Help Now!

Hello fellow DIY enthusiasts,
ersteinmal danke für die vielen Hinweise und Problembehandlungen die ich hier im Forum erhalten habe. Absolutely fantastic!

Okay, now let's get to my problem!
The well-known problem with the TDI engine is occurring again. I've been to Bosch several times, supposedly specialists in this area, and also to a VAG dealership.
"I've been to several workshops, but no one can really help me. They just want to replace everything possible without testing anything, just based on a gut feeling."
Ach so, die Symptome: Leistungsverlust!!! Der äußert sich so, schlechte Gasannahme, Flexibilität in den oberen Gängen schlecht, z.B. ich fahre 120 kmH im fünften Gang und möchte dann schnell auf 150 kmH beschleunigen, dann tut ersteinmal gar nichts es dauert und dauert bis er in die gänge kommt, wärend er Versucht zu beschleunigen hört sich der Motor auch irgendwie komisch an, so als wolle er und könnte nicht. In den unteren Gängen fährt er fast normal, man hat immer das Gefühl das im die richtige Kraft fehlt! Ich habe das Fahrzeug einen III Golf TDI Modell 95 mit 90 PS vor einem halben Jahr gekauft. Nach dem kauf wurde festgestellt das das Ladedruckventil defekt sei. NacI'm sorry, I can't translate that. It appears to be a single word with no context. Please provide a complete sentence or paragraph for me to translate.
"After the valve was replaced, the car ran like crazy. After 2 months (10,000 km), there was suddenly a jolt on the highway, and then it started running poorly. At the Bosch service, they supposedly determined that the mass airflow sensor (MAF) was defective. They replaced it, but the car didn't run any better afterward. After many discussions on the forum and working under the car, I discovered that the boost pressure valve was faulty again. Now there's a new one installed, but it still doesn't run properly. It's better, but not like before. My next step was to go to a VAG specialist workshop (which I was hesitant to do), and they thoroughly checked the entire engine, including compression (25:1), fuel injection timing (OK), etc. They couldn't test the injectors because they didn't have the necessary equipment. There were no error codes stored. Otherwise, they said everything was fine."
Okay, that's enough for now!

Was kann das Problem sein? Die Pumpe vielleicht? The nozzles?

Sure, no problem! Just provide the text you want me to translate.
Patrick.

Oh, so the car now has 136,000 km on it. Actually, my TDI is still relatively new.

reuselkopp wrote:

While he tries to accelerate, the engine sounds strange, as if it wants to but can't. In the lower gears, it drives almost normally, but you always feel that it's lacking the right power!

Hi.

I only have a short amount of time.

The above seems to indicate a problem with the fuel injection system.
It could be related to the NBF (presumably a specific component) or the pump.
The standard leak test for injection molding machines rarely, if ever, detects such faults (especially in the pump).

Do you have a way to log the start of the injection process during a trip?

A stuck EGR valve could also be the cause, although this often results in increased soot emissions at full load.

Addendum:
I'm assuming the standard mandatory tasks, such as fuel filter replacement, etc., are already completed.

Hi Ulf,
What is the NBF? Is that the start of funding? It has been reviewed. The only option would be to go to Bosch again and bother them.
Regarding the soot, I mean that it does produce soot when I accelerate hard. When I look in the rearview mirror, I can see blackish-brown smoke coming out. Does it have to be a lot of smoke to indicate that the EGR valve isn't closing properly? But if it weren't closing properly, wouldn't the turbocharger lose pressure? Or would it? How can I check if the EGR valve is closing correctly?
Die Pflichtübungen habe ich natürlich erledigt Filter wurde schon zweimal gewechselt, sogar das Vorwärmventil. OhGreat success!

Best regards, Patrick.

Hi,
Okay, it's me again. Are you referring to the needle lift valve (NBF) when you say that? I've already done the test for the needle lift valve, but I didn't hear any misfires. What I've also noticed while driving is that when I accelerate, the car jerks (stutters) very gently. This would again suggest a faulty needle lift valve. Or would the car then be bucking more noticeably?

Best regards, Patrick.

reuselkopp wrote:

Okay, here's the translation: It's me again. Do you mean the

needle lift valve (Nadelhubgeber) by "NBF"? I've already done the test for the }needle lift valve, but I didn't hear any misfires. What I also noticed while driving is that when I accelerate, the car gently jerks (stutters), which would again indicate a faulty }needle lift valve. Or would the car then really buck? }

Hi.

Yes, NBF and NHG are the same thing.

Slight jerking can sometimes be caused by the fuel injector.

Visible soot, which can be seen in the rearview mirror during daylight without any modifications, likely indicates an issue with the AGR valve, in my opinion.
To check this, you need to open the intake path on the exhaust manifold and inspect the movement of the valve stem. If necessary, you can use pliers or something similar to free it up.
Unfortunately, I don't know the details of the story regarding the 90 horsepower model.

Hi!

Simply slide a hose onto the EGR valve and suck on it firmly, while using a flashlight to check if the valve opens. After the sudden removal of the vacuum, the valve should close with a click. If it doesn't, replace it, or better yet, disable the EGR system -> see the article on Exhaust Gas Recirculation. In my case, the EGR valve caused a 3 to 5 mm thick layer of soot and oil in the intake manifold and cylinder head (174,000 km, 1Z) -> which restricts airflow. Cleaning can only be done with the cylinder head removed. However, the NHG (Nitrogen Oxide Heat Exchanger) can be replaced proactively (I know someone who replaces the NHG every 90,000 km).

Best regards, Christian.

Hi!
'My TDI exhibited similar symptoms. Ultimately, the wastegate valve (AGR) had to be replaced because the diaphragm was torn.'

Hi,

Mathias wrote:

Ultimately, the wastegate valve (AGR) was replaced because the diaphragm had a crack.

"Don't you think that's a bit of nonsense?"
Exhaust gas recirculation (EGR) and the wastegate are unrelated.

Best regards, Rainer.

Rainer K. wrote:

Exhaust gas recirculation (EGR) and the wastegate have nothing to do with each other.

However, both have a membrane-actuated mechanism.

*ouch* don't hit *ouch ouch*

[Translating...]

Hi everyone,
It's really great how things are progressing here!
Okay, I've already tried the test of attaching a hose to the EGR valve and using suction, but it didn't really work. I couldn't generate enough vacuum with my mouth.
Bei laufendem Motor öffnet sich, zumindest was man so sieht (Die Membran bewegt sich) das AGR Ventil. Bei ungefähr 3000 U/min. geht das Ventil wieder zu. Was es dabei für Geräusche macht weiß ich nicht. Warum ist das denn so wichtig ob es ein hörbares klack macht? Kann man.
Then they would say it's 100% certain?
I'll try installing that metal piece this weekend.
At what RPM should the EGR valve open and close?
Here's what else comes to mind regarding the soot: When I give it full throttle while idling, a lot of black smoke comes out of the exhaust, and directly underneath, there's a large black stain. I always thought a little bit of soot was normal for a diesel engine.

Best regards, Patrick.

reuselkopp wrote:

Okay, I've already tried the test of attaching a hose to the AGR valve and sucking on it.

But that didn't really work.

Quote:

I couldn't generate enough vacuum with my mouth.

Hi.

No wonder, the can needs a good amount of vacuum. Get a large syringe (ideally around 50 ml), it will work better with that.

Quote:

At what RPM should the EGR valve open and close?

It can't be stated that simply, as it also depends on the engine load/boost pressure and is controlled by a complex map.

}What else comes to mind regarding soot is that when I give it full throttle while stationary, a lot of black smoke comes out of the exhaust, and directly underneath is a large black spot. I always thought that a little bit of soot was normal for a diesel engine.}

That's probably quite serious... either it's an EGR problem again, or there are leaks in the charge air pipes. They usually reveal themselves with whistling noises, especially under full load at around 2000 rpm.

Ultimately, the wastegate valve (AGR) was replaced because the diaphragm had a crack.
'Don't you think that's a bit of nonsense?'
Exhaust gas recirculation (EGR) and the wastegate are unrelated.

Greetings, Rainer

It smells strikingly!
Sorry, I was a bit confused. While the wastegate also regulates emissions, the AGR (Exhaust Gas Recirculation) system shouldn't be related. However, I would still have the function of the wastegate checked, as the loss of power disappeared after I replaced it.

Hi,
The actual wastegate is located inside the turbocharger and cannot normally be replaced. Are you referring to the electric control valve?

Best regards, Rudi.

ulf wrote:

No wonder, the can needs a good amount of vacuum. Get a large syringe (ideally around 50 ml), it will work better with that.

Hi Ulf!

Okay, I tried it with a hose on 3 1Z engines (one even had a new EGR valve), and I didn't have any problems getting the hose to the valve. So maybe it's just stuck and not closing properly?

Best regards, Christian.

haehnlein wrote:

So, I tried it with a hose on 3 1Z engines (one even had a new EGR valve)->no problems getting the hose to the valve. So maybe it's stuck and not closing properly???

Hi Christian,

Hmm... I can't open the EGR valve with my mouth .
Perhaps the dosages differ for the various engines .

If the oil pressure of one engine is noticeably lower than that of another, identical and apparently intact engine, there might be something wrong with the first one - unless production changes occurred specifically at this point.

Stubborn or stiff pumps often reveal themselves by the fact that the dispensing motion cannot be easily and precisely controlled.
Instead, the pressure change lags behind the movement, and/or it "jumps" when certain pressure thresholds are exceeded or undershot.