AXD PD Dichtsatz / Anlassdrehzahl kalt | Posts 16+

I borrowed the fuel pressure gauge from again today to check the pressure myself.



I now have a free-running speed of 4.5 bar.

From 1500 rpm, the pressure is 8-9 bar.

If I'm using the LL to return, it will regulate at 8-9 bar.

That should, after all, be exactly right, as I recall having read it, right? Which means the PDE rings and the pump should be okay. Okay.


However, the pressure immediately drops back to 0 after the system is turned off. Should he do that?


Thank you.

7.5 bar at higher speeds is the target value. 3 bar at 1500 revolutions is what older Leifäden still specify. The value is fine as it is. Was the pressure gauge stable, or did the needle vibrate significantly?

The needle was steady at both 4.5 (exactly 4.4) bar and 8-9 bar (exactly? mea culpa: I didn't notice).

The following keywords are:
-Read starter RPM. Disconnect the PD plug from the head and proceed.
-Verify the plausibility of the temperature sensor values.
-Check the amount of the pre-feed pump. Remove the hose and take it for measurement, perform the initial setting on MWB 35 Stage 1. 1 liter per 30 seconds should come out.
-Measuring compression would also be a topic. Perhaps first read out the LLR, as that is simpler. Sometimes you can already see deviations there.

Hello Steffen, thank you for your help.

That will probably take a little longer now.

If I continued, would I then write it here and hope that you would review it again?

LG

Can the check valve be tested/replaced?

What is the internal diameter of the fuel lines?

I currently don't have the time to work on the vehicle; however, I have inspected the fuel system and now have the following questions:

If air enters the system through the PD seals, according to my understanding, the fuel then flows back through the return line.

However, the pre-fill cannot occur because there is a check valve on the tandem pump.

Even if the fuel is now missing in the return line, the feed line should be full, and the car should start up after a short run. Only the return flow from the PDs to the pressure relief valve in the head needs to be filled.

However, since organ pumping can take up to 30 seconds, it is my opinion that the VL is also empty when the pump is empty; the VL to the filter is already being filled by the in-tank pump beforehand.

Therefore, the error must be in the check valve on the pump.


Has this potential source of error been eliminated?

Often, one reads that replacing the tandem pump solves the problem better. Since the check valve is located there, it could very well be the cause of the problem.

engl wrote:

However, organ playing can take up to 30 seconds. ...

... Would I first check the operating speed...

Today, I replaced the fuel filter; I don't necessarily believe it, but it had been in there for quite some time.

The starting RPM in a warm state won't be much of a factor, will it? That would be easy, since I'm already going to the store tomorrow and could test it there.

Getting a tester early in the morning and cold is a bit more difficult. But I will do it.

Quote:

Getting a cold and early morning test sample from someone at home is a bit more difficult. But I will do it.

One must differentiate. Is there air in the system, will the engine then, after a time x,
starts up one cylinder after the other, so it doesn't immediately run smoothly.

If the starting speed is too low, nothing happens until this speed is reached.
Will it eventually be achieved, should the engine start simultaneously on all cylinders?

When I changed the filter, I filled it with rapeseed oil. Then I let the engine run for about 5 minutes. The next day, it started immediately. After he had another argument today, I think this success is related to the lower viscosity and not the filter.






I just measured the idle speed, but it was with a warm engine:

She immediately reached 210 RPM, then 231 RPM after 4-5 seconds, and remained constant.


Is this correct?

engl wrote:

Does this work?

You need the starting RPM for the operating condition with the issues.

Cold:
Coolant temperature 22.5 °C

Operating Speed:
Initially 189 RPM, then after approximately 15 seconds, 210 RPM.


After I reconnected the PD cable, it turned on immediately.

engl wrote:

Operating Speed: Initially 189 RPM, then after approximately 15 seconds, 210 RPM.

Now go find your mistake.
189 is damn close. It should be at least 200.

Normal starting speeds are between 200 and 300 RPM. This puts you at the lower end. Should further influences arise, then you will be well below 200.


As far as I vaguely remember (I don't have the documentation handy), the PD-TDI 250-280U/min requires.

Bertil wrote:

As far as I vaguely remember (I don't have the documentation handy), the PD-TDI 250-280U/min requires.

This pretty much aligns with (some) software-based warm-start locks.

I already know how to properly test a battery; a short test resulted in a voltage of 12.6 V with the ignition off, which would correspond to an assumed state of charge of 75 %.
Upon turning on the ignition, the voltage immediately drops to 11.8 V, which seems a bit low to me.
Next, I will examine the battery, as described in the technical article.