Audi A6 4B 2.5 Tdi - The Classic: Not running.

Hello everyone,

I hope you haven't gotten tired of this topic yet, especially since this is my first post here ;)

I'm trying to summarize:

I bought an A6 to use for tinkering and to learn more.

Regarding the car:

A6 4B 2.5 TDI Avant Quattro
6-speed manual transmission)
Engine code: AKE
132 kW
Year of manufacture: 2000
Mileage: 240,000 km
Note: The previous owner didn't have it for 40,000 km.

What has happened so far:

According to the previous owner, he parked the car and the next day it wouldn't start.

The ESP control unit was replaced by him, but the four lines to the solenoid valves were not insulated. You can find a photo of this in the attachment.

There was air in the diesel line, I properly bled the pump and, while I was at it, replaced the diesel filter.

Diesel is spraying from the lines to the injectors, and it seems like there is pressure.

So far, no success. The engine turns normally when starting, there are no noticeable noises, and there is no "empty" revving (low compression). The battery is newly charged. But it makes no noise, no coughing, nothing. :cry:

So, my assumption was: not mechanical, but control.
I also received confirmation from a free OBD diagnostic software: Engine control unit (ECU) locked.
I purchased a VCDS here through the shop, and I'm also actively reading the documentation. I mainly wanted to know if there were any other error codes hidden from me.

Error codes (with VCDS):

Zitat:

------------------------------------------------------------------------------- Address 01: Engine Electronics Label file: DRV\059-907-401-AKE.clb Part number: 4B2 907 401 Part: 2.5l/4VTEDC 0000SG D01 Coding: 01015 Serial number: WSC 02325 VCID: 5DE6699BA422CE9F3A7-4B1E Subsystem 1 - Part number: 00010059 Part: 130 106EC150_1.R75746441083 00010059 130 106EC150_1.R75746441083 1 Error found: 17978 - Engine Control Unit Locked P1570 - 35-00 - Readiness: Not Available ------------------------------------------------------------------------------- Address 17: Control Unit Insert Label file: DRV\4B0-920-xxx-17.lbl Part number: 4B0 920 900 C Part: C5-INSTRUMENT CLUSTER VDO D11 Encoding: 00060 Serial number: WSC 00000 VCID: 1D66299BE4A28E9F7A7-5160 Part: AUZ7Z0Y1400290 ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ AUZ7Z0Y1400290 1 error found: 01176 - Key 07-10 - Signal too small - Sporadic -------------------------------------------------------------------------------

So, it's no surprise that he doesn't want to start. The engine control unit error cannot be cleared either. The "key error" was sometimes present again after one or two attempts to start, but it can also be cleared again.

The WFS lamp briefly lights up when the ignition is switched on and then goes out normally. It also no longer comes on when starting.

When starting for the 2nd or 3rd time (always no more than 10 seconds), it beeps and the oil pressure warning light comes on, but there is no error code. Overall, I have tried to start the car about 10 times over several days after bleeding the system. Before that, of course, it didn't start. All without a start pilot.

My next step would be to replace the ESP control unit again, as I believe that, due to the uninsulated wires, it may have been completely wiped out. Or alternatively: because I don't know if the previous owner's starter attempts caused the ESP to draw in air, I would immediately replace it with a new one. The ~600 Euros would still fit within the budget.

Another consideration was whether the angle sensor was incorrectly positioned and that was causing the problem. But wouldn't that also mean there would be other error codes?

My question to you: Do you see it the same way? Or does anyone have another suggestion for what else to check?

I hope that "another post" about the 2.5TDI doesn't cause anyone any trouble. :wink:

And I also hope that I haven't forgotten anything. :roll:

Thanks in advance,

Maxi

Hallo

Zitat:

I bought the VCDS here through the shop, and I'm also diligently reading the documentation

Tip: If you use the same email address for your forum account and in the shop, you will be automatically recognized as a customer. :idea:

The issue with the WFS needs to be resolved before you continue searching for the problem.

Have you tried getting the actual injection start value from the engine control unit's measurement blocks during the starting process?

Best regards, Rainer

Hello,

Thanks for the tip about the email, I've already changed it. +1

I'll try using the second key this afternoon, maybe that will work.
And no, I haven't tried that yet. I'll also try that today and let you know the results. :)

Regards,
Maxi

Good evening everyone,

First of all: Sorry for the duplicate responses.

With the secondary key, there are no WFS issues. I will take care of the other one once the car is running.

The locked engine control unit was again recorded as an error, but this time it could be deleted.

A start attempt. No response, but error-free.
I then called up the MWB 004 and recorded the next start.

First five lines:
[quote]
Injection start
(Target in °v.OT)

1/min	Injection start (Actual in °v.OT)	Valve for Injection start
0	5.0	0.0	0.8
93	4.8	0.0	0.8
139	4.4	0.0	0.8
116	4.6	0.0	0.8
139	4.4	0.0	0.8
116	4.4	0.0	0.8

The values remain within the specified range.
The battery is no longer fully charged, but the subjective feeling is that the RPM is high enough to start the engine. However, the values seem a bit low to me, or am I mistaken? Perhaps the angle sensor? Or is the control unit measuring something else?

The error message for the locked engine control unit appeared 2-3 attempts later and after a few minutes without the engine running. Otherwise, there were no other errors.

I'm starting to feel like I've really lost my way, and I hope I haven't made things worse.

Best regards,

Maxi

Hello,

If the actual injection start remains fixed at 0.0°vOT, this indicates that the engine control unit cannot determine the SB at all.
-> Either nothing is injected, the needle lift actuator is defective (less likely), or the injection start is completely wrong. 139 rpm is much too low to start, and it could also be that nothing is injected because of this. -> Charging device

Best regards, Rainer

Hello everyone,

a quick update: The Audi is running.

The angle sensor was clearly misaligned and not centered. I aligned it parallel to the sensor wheel and the side wall. The Audi started immediately, but the engine speed is a bit erratic when stationary (approximately half a finger-width jumps).

Next, I will check the fuel injection timing and possibly adjust the fuel pump.

I will continue to post my findings here, perhaps it will help someone.

Thanks so far ;)

- Maxi