T4 2.5 TDI: Fuel Injector Calibration Issues

Hello you hardworking mechanics!

Key data: ACV 4/97, 460,000 km.

My better half's VW T4 broke down today.
Simply lost power.
The error memory contained 3 errors.
Donor for slide valve travel G149 35-00.
Quantity setting (N146) 18-00, upper limit.
Quantity setting (N146) 19-00, lower limit value.
The errors reappear immediately after being cleared, even without attempting to start the system.
The pump was overhauled 50,000 km ago by a "specialized workshop" with a brand new fuel meter. This was done as a preventative measure at the time.
Unfortunately, that's when the problems really started. Shortly after, we had a breakdown, 800 km from home. A solder joint connecting the mass flow meter to the pump had come loose.
After the adjustment made by the manager himself (I would have preferred an expert), the quantity setting was too high and the start of the feeding process was set too early. Quote: "I thought they might appreciate a little more output."
That's the background information.
Therefore, I wouldn't rule out the possibility that the pump technician messed something up again.
In a similar case, I read that the impeller had become twisted.
According to my initial inspection, at least the drive belt is very tight.

I would really appreciate your ideas!
Sure, no problem! Here's the translation:

"Thank you in advance!"

Hello,

The regulator is quite simple; just remove the cover and take a look. Also, check the wiring!

See also:
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

Best regards, Rainer.

Thank you very much, Rainer, for the quick response!

I'll definitely take the lid off quickly.

I was just thinking that perhaps the errors in memory might indicate a certain level of damage.

Hi there,
Could you also provide us with the values from MWB 019 (with ignition on)?
hg
Herbert.

Sure!
Anything you want!
5.040 V Upper Limit Setting.
5.040 V Starting voltage protection.
And if it's helpful, I'll add another beer on top .

Hi there,

The lower limit should be between 0.54V and 0.88V, while the upper limit should be between 4.1V and 4.88V!

The engine should no longer be running under controllable conditions.
Perhaps the donor lever is loose or hanging on the upper mechanical stop.
To be sure before opening the quantity setting device, please post a Screenshot of MWB 001 and MWB 019 with the ignition on.
hg
Herbert.

I would also suspect that the injector has come loose from the cone. At points 074-0.76 (MWB1), adjust one engine cylinder at a time and test.

I can imagine a broken cable in the area where the body meets the engine. I've experienced this myself before, for example, on a Golf III TDI and a Passat 35i TDI.

/viewtopic.php?t=27960&highlight=golf+tdi

Thank you for the interesting suggestion!
Actually, the bus had an accident once where all the cables to the control unit were severed.
I carefully restored it back then.
But with these types of vibrating plates from Motor, you can never be sure.
Unfortunately, I haven't had a chance to disassemble it yet, as I want to make sure it's on our property before I open the pump.
It should be happening tonight.

Hi.
You can also measure directly at the connector on the pump to determine whether the fault is located in the area of the signaling system or in the wiring harness or control unit.

Measurement values should:
Pin 5 to Pin 6: 0.4 - 1.0 Ohms (at 15 - 30°).
Pin 4 to Pin 7: 1.2 - 4.0 kOhms (at 15 - 30°C) (Temperature sensor, which should be irrelevant in this case).
Pin 1 to Pin 2: 4.9 - 6.5 Ohms.
Pin 2 to pin 3: 4.9 - 6.5 Ohms.
Pin 1 to Pin 3: 9.8 - 13.0 Ohms.
Pin 3 to pin 5: Minimum 1.0 MOhms.
Pin 6 to pin 7: Resistance 1.0 MΩ.
All pins to ground: Minimum 1.0 MΩ.

Measure everything with the pump plug disconnected.
Greetings.

While the latter provides static values, it is meaningless for the actual testing of the quantity setting device.
hg
Herbert.

Hi.
It's not enough to simply rule out something like a loose retaining ring; it could still be loose even if the readings are correct.
An electrical problem in the signal box, such as a broken weld at the cable entry point, can be detected.
"I have a signal box here, also from an ACV, that exhibits exactly the same symptoms. There are errors in the control unit that cannot be cleared. The feedback voltage is around 5V, and as far as I remember, there are precisely those three error codes related to the signal box."
If I test this circuit, there is no continuity between pins 1 and 3, nor between pins 2 and 3. Similarly, there is no continuity between pins 5 and 6.
After installing the pump, the motor received a different control signal and is now running smoothly again.
"Since the observed symptoms closely match the expected behavior, and we suspected a signaling system defect based on electrical measurements, which we then confirmed, I would definitely invest those few minutes to perform the necessary tests."
Visually, you can't see much at the signal box, although they haven't removed the sensor or the circuit board yet, only the black plastic cover. All the welding points are still in place.
Best regards, Matze.

Hi!
You are right, it makes sense to perform a test before opening the MSW file.
hg
Herbert.

Error found. And "history repeats itself."
Apparently, the "pump professionals" who refurbished the pump weren't very good at soldering.
Once again, the workshop was to blame, and once again it was a faulty solder joint near the turnout mechanism.
The first time, we had to be towed home for 800 km and had to rent a car for a week. This time, it was only 80 km to get us back home.
Had this happened a month earlier, it would have either cost us our Iceland vacation and therefore €2000, or it would have inevitably extended our stay in Iceland .
I would definitely have taken the pump repair shop to court.
"As a precaution, the fuel pump was professionally refurbished at 400,000 km, but this turned a car with no previous breakdowns into an ADAC (German automobile club) member's frequent call-out vehicle. In total, there were 3 breakdowns: once, the cable from the shut-off valve vibrated loose because it was poorly attached."

I'm interested in knowing if there's anything I can use to prevent future open solder joints. It also needs to be something that won't dissolve, so it doesn't get processed by the pump.
Would heat shrink tubing over the solder joints be an option?
I finally want to get the bus back in a stable condition.

Thank you everyone for all your great help!
Here are real professionals with expertise and a willingness to help!

Hi,

Is the protruding wire at the soldered joint under any tension? It shouldn't be. Either something is vibrating that shouldn't be, or there's an issue with the solder itself, or someone might have been messing around with it improperly.
Solder becomes brittle if it is repeatedly heated to excessively high temperatures with the soldering iron.

Best regards, Rainer.

Hi Rainer!

My speech!
In my opinion, the wires should not be under tension but rather should be placed together with pressure on each other while still being un-soldered.
Unfortunately, it seems the owner of the workshop didn't take me seriously when I told him that at the time.
Unfortunately, it's now difficult to bend the wires, so I hope to find a way for these wires to create a permanent connection.