Injector Pump Control Unit Tuning/Adjustment

Hello,

I'm new here and have a few questions that I haven't been able to find answers to, even after searching for a long time. Maybe someone can offer some advice.

My A6 2.5 TDI with engine code AKN simply wouldn't start last week. The diagnosis from the dealer after towing it was a faulty VP44 injection pump. I picked up the car, obtained a refurbished VP44 (with a report from Bosch), and replaced it. However, the car still won't start. The injection pump is definitely supplying fuel, and after prolonged cranking, the engine smokes slightly from the engine bay and exhaust, but it still doesn't start. It seems like the injection timing might be off. The valve timings are correct, and I fed the pump with fuel both through the diesel filter and directly from a canister (pre-feed), but without success. I bled the system as much as possible, and I didn't see any air bubbles in the supply line, but I'm not completely sure that all the air is out. It seems like there might be an electrical problem. Could the control unit of the new pump also be defective? How do you test or read it out?

My main question is whether the pump needs to be electronically adjusted or unlocked in any way using VAG-COM. I read something in the forum posts about channel 50, which supposedly allows you to adjust the pump, but unfortunately, there's no information on how to do it or what steps to follow. I also read that Bosch service centers adjust all the pumps and that they should work immediately after installation.

The car is a 2000 model, and according to the report, so is the new pump, although it's from an A4. I have no idea if that's relevant, but the part number is definitely the same (059 130 106 B). According to Audi, the pump control units haven't been integrated into the WFS system until 2002. There were also no error codes stored in the engine control unit I, and I can't access the diesel pump control unit (41) with VAG-COM.

I also tested the preheating relay (202) by applying 12V to terminal 86 and grounding terminal 85. It works perfectly, and the ohmmeter shows the normal values for terminals 30 and 87 in both the switched and unswitched states! Can I assume that the relay is okay, or could it still be faulty?

Could the problem possibly have a completely different cause? I've read something about potential issues with this engine. How does that manifest itself? There are no unusual noises when starting the engine.

Bin über jeden Tip mehr als dankbar, vielleicht hab ich ja was total vergessen oder übersehen. DThank you...

Best regards, Sven.

The pump is not connected to your WFS loop.

Yes, I thought so too.

Does anyone have any other ideas ?

Best regards, Sven.

Did you bleed the system using an external pump connected to the return line?

Yes, I tried using a vacuum pump on the return line, but with only moderate success.
Diesel has been present before, but not to the extent that it was flowing in streams.

Audi sagte das daß entweder mit Luft im System oder mit anlernen/freischalten der Pumpe zusammenhängt das der Wagen nicht anspringt. Ich hatte meine Zweifel aber ich hab sie rangelassen. 2 Tage später rief ich an und fragte nach meinem Fahrzeug. Aussage war das die Pumpe nicht freigechalten werden muss und auch keine Luft mehr im System ist. Zum laufen gebracht haben sie ihn bis heute auch nicht. Nun liegt die Vermutung nahe das es ein Motorschaden ist bzw eingelaufene NW der Grund sind. Kompressionsmessung steht nun an. Let's see...

Best regards, Sven.

Okay, as mentioned before, WFS didn't connect the fuel pump to the engine. When bleeding the system, run the vacuum pump until diesel starts flowing, then crank the engine while the pump is running. Ideally, temporarily loosen the locking nuts on the injector sleeves. Are the valve timings correct? If the fuel pump is 180 degrees out of alignment, the timing pin will always fit...

Yes, that's exactly how we did it. We connected the pump to the return line and pumped until diesel started flowing. It did flow, but then we tried starting the engine while loosening and tightening the fittings in sequence, without any success.

I've also considered the possibility that the pump was installed incorrectly, but I don't think that's possible. For a complete cycle, the pump would need to rotate twice, meaning all six cylinders wouldn't be serviced until after two rotations of the pump. However, I believe the pump services all six cylinders with just one rotation, which means it's always in the same position when disconnected.

According to Audi, the pump cannot be installed incorrectly, and I think so too.

Best regards, Sven.

It's a four-stroke engine, which means one cylinder only fires every other revolution. I wouldn't be writing this if it hadn't happened to me before, usually at the end of a long operation. It shouldn't happen, but that's just Murphy's Law.