A6 C4 2.5L AEL: Poor Performance & Smoke

Hello,

First, let me briefly introduce myself. I recently got my third TDI, an A6 C4 with a 2.5L AEL engine.
with already 320,000 kilometers on the odometer.
Before that, I had a Skoda Octavia with 110 horsepower, and before that, a Lupo 3L TDI.

I have already read almost all of the posts about the 5-cylinder AEL engine.
I systematically went through the process of debugging.

The problem is that the engine feels weak above 3,000 RPM, and the exhaust produces a noticeable amount of smoke.
The turbocharger pressure is within the normal range and builds up from 1,800 RPM, maintaining a pressure of 0.8-0.9 bar up to 4,000 RPM.

Today, I logged the start of the injection process using a measurement run, and I noticed that...
As the engine speed increases, the ignition timing progressively shifts towards a later point.
That means the actual value curve deviates significantly from the target value curve.

At 4,000 RPM, VAG-COM shows a target value of approximately 17 degrees, but the actual value is only around 4.5 degrees.

However, the injection timing at idle is fine, at approximately 0.5-0.7 degrees, and the engine starts perfectly.

Now, to my question: Is there a possibility of resolving this issue through a static configuration setting?
Do you need to fix the spray start issue, or do you need to repair or replace the pump's mechanics?

Thank you for your responses!

Best regards,
Stefan

The fuel pump in your modified AEL is likely worn out. This can happen with 320,000 km. -> Replace the ESP (Electronic Stability Program) module.

Best regards, Rainer.

I don't see why it would need to be tuned, where did you get that idea?

Best regards,
Stefan

An injection start value of 17° KWvOT at 4000 rpm is NOT normal in the standard configuration.
Perhaps the pump isn't actually defective, but the dataset is simply flawed – who knows for sure?

@Rainer:

I'm sorry, I bought the car two weeks ago, and it came with the modifications already installed.
not possible.
I drove a series AEL vehicle some time ago, and it performed much better.
I just want to get the system back to its original, error-free state first.

I would like to post my log files here, but I'm unfortunately not sure how to do it.

Would you like me to send you the files via email?

Can you also rebuild my fuel injection pump if it's defective, or does it have to be replaced with a new one?

Best regards,
Stefan

You can have them refurbished by Bosch, or you can get a used one with as few kilometers as possible from Schrotti.
Vorher wäre es aber sinnvoll hier ein Log hoch zu laden. See also:

Okay, I'm ready. Please provide the German text you want me to translate.

Okay, I finally figured out how to attach a file.
Perhaps this is more informative now.

The yellow line represents the duty cycle.
the blue line representing the target injection start.
and the pink line indicates the start of fuel injection.

Best regards,
Stefan

Have you already replaced the diesel filter?
Air in the lines?

I contacted customer service right after I bought it.
The diesel and air filters are new.

Perhaps these two logs might be helpful.

Best regards,
Stefan

I've also seen 17 degrees on an AEL before, so it's likely original.
Is the pump setting correct?
Possibly insufficient internal pressure in the pump?

Can an ESP (Electronic Stability Program) be refurbished or rebuilt?

manfred5 wrote:

Is it actually possible to overhaul an ESP?

Sure, that's possible, but if the pump, especially the pump housing, is mechanically worn out, it's not worth it. -> Replacement pumps are available from Bosch.

Thank you . That's exactly what my question was about, and I'm torn between various statements:

1) At 'Freundlich,' you haven't even stepped through the door, and someone is already recommending a new ESP (okay, maybe a bit of an exaggeration, but essentially that's what happens).

2) Bosch operates similarly, likely also to be on the 'safe' side and to avoid complaints and, consequently, dissatisfied customers.

3) I find a ton of GOOD tips in the forum (great forum, by the way), and I've even sealed 2 pumps myself. However, it's always just been about sealing or adjusting, even with the MSW pump on the AEL system. (Thanks to the forum, it worked out excellently).

How can you tell when wear and tear is beyond repair? Obviously, if there are only metal shavings left, it's clear, but what about bearings and other components?
Bei meiner AEL/AAT Pumpe zum Beispiel wandert der ESP im bekannten VAG-COM Bild erheblich. Pumpe hat aber 'erst' 180 TKM auf der Uhr. And now?

I thought it would be a good idea to create an illustrated guide for 'ESP overhaul.' There are already very good instructions in the forum for replacing seals and for MSW (Motor Starting System) procedures.



Here's a usage table (unofficially, and subject to confirmation) for one of:
Diesel fuel injection pump manufacturer: Bosch 0460 415 989 / 046 130 108.


Year of Manufacture | kW | HP | cc
AUDI 100 (4A, C4) 2.5 TDI 12.90-06.94 85 115 2461
AUDI 100 Avant (4A, C4) 2.5 TDI 12.90-06.94 85 115 2461
AUDI A6 (4A, C4) 2.5 TDI 01.95-10.97 84 114 2461
AUDI A6 (4A, C4) 2.5 TDI 06.94-10.97 85 116 2461
AUDI A6 (4A, C4) 2.5 TDI 08.94-10.97 103 hp 140 lb-ft torque 2461 cc engine.
AUDI A6 (4A, C4) 2.5 TDI quattro 10.95-10.97 103 hp 140 lb-ft 2461 cc
AUDI A6 Avant (4A, C4) 2.5 TDI 01.95-12.97 84 114 2461
AUDI A6 Avant (4A, C4) 2.5 TDI 06.94-12.97 85 116 2461
AUDI A6 Avant (4A, C4) 2.5 TDI 08.94-12.97 103 140 2461
AUDI A6 Avant (4A, C4) 2.5 TDI quattro 07.95-12.97 103 hp 140 lb-ft 2461 cc

Regards,
Manni.