A6 TDI (AEL) Excessive Smoke: Part 2

Hello everyone,

I recently posted about my TDI smoking excessively when accelerating. I received a response suggesting it might be related to the fuel injectors. Now, someone is on vacation, and I was hoping to have someone check it out. (But I'll do that soon.)
So, I first inquired with a diesel specialist at Bosch.
He said that, regarding the effect (extreme black smoke), it definitely wasn't the fuel injectors. More likely, it was the fuel pump.
As mentioned in the previous post, everything else is fine (including the mass airflow sensor, EGR valve, turbo, etc.).

Now, finally, to my question:
Can an injection pump be repaired or refurbished?
Is it even worth it? This thing is REALLY expensive!
There has to be a cheaper way to do this...

Regards,
Wool.

Hi,
Okay, I wouldn't immediately suspect the fuel injection pump. If the engine is otherwise running well, I would first check the turbocharger boost pipes. If there's a leak in those pipes, it can cause too much diesel to be injected, which would result in excessive smoke.
Then, check the EGR (Exhaust Gas Recirculation) system.
Air filter.

Hi Tim27,

Thank you for your post.

If there were a leak in the air intake ducting located behind the turbocharger but before the mass airflow sensor (MAF), it could result in reduced power. However, it wouldn't necessarily cause any smoke, because the engine control unit (ECU) would only receive information about the actual amount of air entering the engine.
If there were a leak in the air intake path behind the mass airflow sensor (MAF), it might produce smoke, but it would have reduced power. The turbocharger and the entire air intake system are in good condition.
The AGR is also fine. I mentioned that before, though... hehe.
(Please don't be upset about the smiley.)

If you could see HOW MUCH he smokes (the black trail on the road when accelerating harder)... unfortunately, it's not the air filter. Too bad, it would have been nice and cheap.

The valve for the boost pressure control is also functioning correctly.

I thank you for the effort!!!

Regards,
Wool.

P.S.
Does anyone else have any information regarding the issue with the pump?
Thank you in advance.

Hi,

"There is no sensor 'behind the turbo, in front of the mass airflow sensor' because the mass airflow sensor is located before the turbocharger. Therefore, it only measures the air that the turbocharger draws in, not the air that reaches the engine."

What happens if you temporarily disable the EGR valve? Will it reduce the amount of smoke?

Something similar happened to me (without the EGR valve, it wouldn't even start), and the cause was a small leak in the intercooler.

Best regards,

Jan.

Hmmmm....is there nothing? (sorry Tim27!!) Then I probably need to delve into it more. I'm really interested in understanding the technology of my car. And I mean really understanding it.

If he had a leak in the coolant system, wouldn't he also experience a lack of power or insufficient boost pressure? Because his is okay.

And I had previously blocked off the AGR valve with a piece of metal. That didn't help; it continued to smoke. It's been open again for a while now, but I'm going to block it off again.

Regards,
Wool.

Hi,

"In the 'Links' section, there used to be a link to a description of the VAG industrial TDI engine, which provides a very good explanation of the entire intake and pressure system."

A leak doesn't necessarily mean a loss of performance, as I learned back then. The car performed very well in the acceleration test (Ulf-test), and also reached its maximum speed (Vmax). Despite the leak, it easily reached a speed of 205 km/h on the speedometer, which corresponds to a real-world top speed of approximately 193 km/h. The only issue was that the engine was running rich because the mass airflow sensor (MAF) was measuring more air than was actually reaching the engine.

Check out http://www.informatik.hu-berlin.de/~richling/tdi/, where you can see the pictures of the two LLK leaks, which, although caused by Russ, didn't result in any performance losses. Sorry for the poor quality; I didn't have a digital camera back then.

However, the fact that decommissioning the AGR reactors didn't achieve the desired results actually suggests that there might not be a leak. But there's another simple test we can perform:

What does the engine sound like when you accelerate from around 1500 RPM with full throttle? Mine used to have a very noticeable hissing sound around 2000 RPM, which was caused by escaping air.

Best regards,

Jan.

Hi Jan,

I'll check out the link. Thank you for the tip.

Regarding your question: The only thing that "faucht" (makes a hissing sound) when I accelerate at full throttle is the drivers behind me... because of the smoke.
Seriously: It actually runs quite normally, and there are no unusual noises like hissing or popping.

I have something new, though.
Ich habe von dem, der im Urlaub ist, gerade jemanden bei Bosch empfohlen bekommen. Da habe ich na klar sofort angerufen und SCHNACK!!! hatte ich einen Termin für morgen. GREAT!!!
He said again that it might still be related to the fuel injectors. So, I will remove them and have them checked.
He also said that I should check the pressure hose behind the turbo for oil leaks sometime. A little bit might be possible, but only a very small amount. I will do that too, but only after the Bosch appointment.
Let's see what insights I can share next time I get in touch...

Oh yeah... the pictures turned out quite well for a digital camera. Everything is perfectly recognizable.
It looks like "cold forming."

Thank you very much, and see you later.

Regards,
Wool.