Leistungsverlust am G3 TDi!!! | Posts 16+

Ahhhh, now I get it!

Well, I'm slowly starting to understand... I've also been diligently reading posts every night.
Okay, I'm going back to the garage to take some measurements!

So habs jetzt nochmal gemessen! Everything's okay...
The resistance is 17 ohms, and 'Spg.' refers to the battery voltage.

So, we're continuing with VAG-COM!

Thank you in advance! You've helped me a lot!

Hello,

What are the target and actual values for the start of the injection process while I'm driving?
It's interesting, especially in the higher RPM/load range, but you're significantly lacking in top speed.

Best regards, Rainer.

Just tested it out on my laptop!

The auscultation (listening with a stethoscope) didn't reveal anything new! Nothing could be heard...

In ad group 00, field 2, the value did not reach 255. The maximum value I observed was 59!

'Quote:'
If the target value is not reached, the injection limiter in the fuel injection pump is blocked.

Now my question: How can I fix it? Or do I have to replace it?




@Rainer
May I link to this forum on my page? I'm still missing some good links .

Hmm, and is the ignition timing definitely set correctly, and is the timing belt sprocket securely fastened to the crankshaft?
Run the same test again, but this time, let the ESP draw directly from a perfectly clean container filled with diesel.
Are there finally no more air bubbles in the line to the ESP (Electrostatic Precipitator)?

If the above steps don't yield a result and the solenoid valve on the fuel injector itself is not defective, it will likely require replacing the entire fuel pump...

Quote:

@Rainer May I link to this forum on my page? I am still missing some good links

.
Sure!

Best regards, Rainer.

Damn, that replacement pump isn't really cheap!

Okay... I'll try again tomorrow and double-check the timing gear. The pump was adjusted by Bosch, so the timing gear should be secure, but I'll check it again just to be sure!

Should I still check the setpoints again? Under full load? Or can I skip that now?

As far as I recall, the valve was connected to a Bosch computer.
It made a motor noise, but that was okay! But I'll try everything again tomorrow... Better safe than sorry! I'll get back to you tomorrow.

Thank you!

Okay, I was just messing around with the laptop again while I was at the car!

It seems like the N108 is not being controlled correctly! The indicator light is constantly on when attempting to activate it!
The valve N18 also doesn't seem to be working when activated. I tested it because I suspect it's somehow related to N108 based on the wiring diagram! Or is it not clicking? Can you only determine this by listening and running the engine?
Although I didn't hear any unusual noise either!

Is there a short circuit or a broken wire somewhere?! But why are there 12 volts present, and why is the light constantly on?

Is it enough to just turn on the ignition to activate the test lamp, or does the engine need to be running?

Is there a specific weak point in the wiring harness where this type of issue occurs more frequently? Because checking the entire wiring harness could take quite a while...

I found a spot where the insulation of the N108 connector is peeled back about 2 cm behind the connector, but the wires inside look okay, so there's no cable break at this point... otherwise, the test lamp wouldn't light up.
I will take care of it as soon as I'm back home!

TDI_Butze wrote:

It seems that the N108 is not being properly activated! The test lamp is constantly lit when attempting to activate it!

Hi.

If you have connected the check lamp in parallel with the N108, it should be off when the engine is not running (ignition on). Otherwise, the injection timing will always be too late, which naturally reduces performance.

Quote:

Valve N18 also shows no effect when activated either; I tested it because I suspect from the wiring diagram that it's somehow related to N108! Or does it not click? Can this only be determined by listening and running the engine?

It's somehow possible to use VAGCOM to make the engine control unit switch between early and late ignition timing while the engine is idling. This can be done either through actuator diagnostics or via the basic settings mode in the injection timing group, although I'm not entirely sure which method.
In any case, you should hear the engine noise change from soft to loud and back again. If this doesn't happen, the fuel injection timing is blocked.

Quote:

Is it enough to just turn on the ignition to activate the test lamp, or does the engine need to be running?

Turning the ignition on is definitely enough for the AFN engine.

Quote:

Is there a specific weak point in the wiring harness where this type of issue occurs more frequently? Because checking the entire wiring harness could take a while...

If there is a short circuit somewhere in the wiring harness leading to the motor control unit (pin 2 of the 3-pin pump connector), the fuel injector will always receive power -> see above.

Thank you all!

I found the error! The cable from the 3-pin pump connector (pin 2) had a short circuit to ground! I replaced it with a new one, and now it's working correctly again!

Best regards,
Matthias

TDI_Butze wrote:

The cable from the 3-pin pump connector (pin 2) had a short circuit to ground! I replaced it with a new one, and now it's working correctly again!

Hi Matthias,

Where (in which area / on the pump side or the vessel side of the 3-pin connector) was the short circuit located?
Were there any pre-existing damages visible (e.g., sharp creases or similar)?

While this is the first time I've heard about such an error, it's definitely the kind of thing that can drive you crazy.
Therefore, I'm considering adding this issue to the list of "common" problems, especially if you didn't experience any external signs.

I'm not exactly sure where the error is, but if you're interested, I can take a look.

I just installed a brand new cable directly from the control unit to the pump!

I found damage directly behind the plug; the insulation appears to have been scraped off.
It looked more like someone had used a soldering iron on it.
'But it wasn't a major issue... by measuring the resistance, I discovered that pin 2 of the 3-pin pump connector is connected to the ground terminal!'
It was approximately 0.something Ohms. The problem is definitely located behind the 'large' motor connector, as viewed from the pump.

So, there were no visible external signs, which is why I was searching so stupidly . No kinks or anything like that... but I've never taken the battery holder off, and I haven't removed the cover underneath/on the water tank either!
I was too lazy to check the entire wiring harness!

'Soon I'll need a new clutch, and since I'll be taking things apart anyway, I'll measure and see exactly where the problem was! Also, I'll check if there's a ground cable somewhere in the wiring harness that's not properly insulated, as that might cause problems down the line.'
I'm still not quite sure where the cable is supposed to make contact with the ground, because the wiring harness is well-insulated, and I couldn't see anything at the exposed ends!

Best regards,
Matthias