BKN Not Starting: Troubleshooting & Solutions

Hello everyone,

Within my circle of acquaintances, I've encountered a new child who is causing problems.
It's a 2005 Audi A4 3.0 TDI that had an engine failure.
A replacement engine was installed, but it's not starting now.
Immobilizer is OK.
What I've observed is that the CR pump isn't building up pressure; it's only reaching around 50 bar.
Diesel fuel is present on the injectors.
The pump is from the old engine and it was working.
Here's the diagnostic scan report; the vehicle still has some errors.

What would you check next?

Thanks so much for your ideas.

hello there!

If the pump only produces 50 bar, you need to look for faults. Either nothing is going in, or there is no pressure build-up, resulting in no diesel being pumped out.
At 50 bar, something definitely reaches the nozzles, but that's not enough.

Bleed the pipes according to the instructions. If that doesn't help, the pump may be incorrectly installed (start of pumping) or the pump itself may be defective.

Was ist die richtige Vorgehensweise beim ersten Start eines Injektors: Soll die Überwurfmutter geöffnet werden und sollte man den Motor laufen lassen, bis Diesel austritt, bevor man sie wieder festzieht? Soll vor dem Start die Railpumpe über den Rücklauf per Vakuum entlüftet werden? Funktioniert die Vorförderpumpe im Tank, falls vorhanden?

Thank you for the answers.

First, the pump was activated using VCDS, and then the locking nuts were loosened.
@ T3Surfer: The pre-injection pump is running, diesel is reaching the injectors. The return line has not been bled.
@ mullemaus: What do you mean by "start of support"? CR pumps don't have anything like that, do they?
What is the correct procedure for bleeding the system, is there a guide for it? Everything I've found so far just says "purge," which I don't believe is sufficient.

@ mullemaus: What do you mean by 'start of support'? Don't CR-pumps not have anything like that, or do you mean something else?

As far as I remember, the pumps, like the 'old' VEP units, must be installed in a specific orientation.

mullemaus wrote:

As far as I remember, the pumps, like the "old" VEPs, must be installed in a specific position.

That's right, it doesn't necessarily have to be exact to a tenth of a millimeter, but it shouldn't be just any random position either.
CR pumps are not designed to be easily disconnected for nothing.

Hello,

Thank you for the answers.
Then the basic settings are probably not correct.
How can I adjust the initial settings? The pump was simply installed onto the new motor.
Can I do that with VCDS?

"Thank you very much!"

Quote:

How can I set the initial alignment? The pump was simply mounted onto the new engine.

There's nothing about that in the RLF. It seems like it doesn't matter.

Hello everyone,

After the diesel fuel is supplied, the engine starts if you use a small amount of starting fluid to start the machine.
Does anyone know what the starting conditions are for this motor (e.g., speed, etc.)?

Thank you for your tips.

SG.

Hello,

"During cold starts, there is typically no minimum engine speed required, but a minimum pressure must be reached in the fuel rail. Therefore, you should check what the engine speed is during starting and what coolant temperature is being displayed by the engine control unit."
Does it only fail when starting the engine when it's cold, or does it also fail when starting it when it's warm?

Best regards, Rainer.

Hello Rainer,

"The engine won't start, I'm having problems with the RPM, and I keep losing the connection to VCDS."
The same applies to the rail pressure.
I'll try a different laptop, maybe it will be better.

What speed (RPM) or rail pressure should be achieved?

"Thank you very much!"

SG.

servusssss wrote:

Hello everyone, After the diesel fuel is supplied, the engine starts if you use a small amount of starting fluid to start the machine. Does anyone know what the starting conditions are for this motor (e.g., speed, etc.)? Thank you for your tips. SG

.... and if the organ is no longer connected to VCDS, it is possible that the power supply to the MSTG is interrupted.

Code:

.... und beim Orgeln keine Verbindung mit VCDS mehr hat kann es gut sein, dass die Spannungsversorgung des MSTG weg ist.

, away or insufficient.

Hello everyone,

A quick update on the patient mentioned above.
Since we weren't sure if it was a cold start problem, we wanted to let the engine warm up.
However, it turned off on its own after about 10 minutes.
Since then, I haven't been able to connect to any control unit!
Fuses and other components have been checked and are working properly.
We still suspect the relay, and we will replace it.
Does anyone else have any suggestions as to what the cause might be?

While the engine was running, I checked a few more things.
The temperature sensors are providing reasonable values.
Fuel injection deviation is less than 1.1 mg/hour.
As well as a rail pressure of approximately 480 bar.
Okay, please provide the German text you would like me to translate.

Code:

Samstag,31,August,2013,17:59:38:28066 VCDS Version: RKS 11.11.5 Datenstand: 20130111                 Adresse 01: Motor  (8E0 910 401 E) 17:59:35 Block 001: Mengenanpassung   819 /min  Motordrehzahl   12.1 mg/H  Einspritzmenge   482.8 bar  Raildruck (IST)   18.0°C  Kühlmittel- temperatur 17:59:35 Block 014: Laufruheregelung 2 (Einspritzmengenabweichung)   0.14 mg/H  Zylinder 4   -1.04 mg/H  Zylinder 5   -0.05 mg/H  Zylinder 6         17:59:35 Block 013: Laufruheregelung 1 (Einspritzmengenabweichung)   0.52 mg/H  Zylinder 1   0.24 mg/H  Zylinder 2   0.14 mg/H  Zylinder 3

I also have the initial conditions.

Code:

Adresse 01: Motor  (8E0 910 401 E) 18:26:27 Block 005: Startverhältnisse (Vom letzten Motorstart gespeichert)   756 /min  Motordrehzahl   5.5 mg/H  Start- einspritzmenge   48.0  Start- synchronisation   48.6°C  Kühlmittel- temperatur

Unfortunately, logging was not possible due to the connection interruptions. Therefore, I can only provide the individual measurement values.
Could the connection interruptions be a symptom of the new problems?

Thank you very much for your ideas!

SG.

Quote:

Can the connection interruptions be a symptom of the new problems?

What new problems? First, the engine won't start, now this.

Are the cables securely fastened to the battery terminals, or are they just loosely attached?
It seems to me, based on the description, that there's clearly a problem with the on-board power supply.

You should check the wiring harness, including making sure that any loose ground connections that were forgotten to be tightened are properly secured.
Then there's the ignition switch. Relay "109" (or possibly a different name) which supplies power to the engine control unit could be a candidate, if it weren't for the lack of connection to other control units. This relay has nothing to do with those other units.

Best regards, Rainer.

Quote:

Are the cables securely screwed onto the battery, or are they just loosely attached to the terminals?

...or maybe something broke off somewhere...

@servusssss You have mail .