TDI: Power Loss After 3000 RPM

Hi everyone!
I hope someone can help me...
'On my Golf 3 TDI (manufactured in August 1996) with the AFN engine (81 kW), an error occasionally occurs.'
'Specifically, the engine only runs in fourth and fifth gear at 3000 RPM; it doesn't go any higher. After that, it goes into limp mode.'
It doesn't happen in the first, second, or third gear! Full power and torque are available! It also doesn't always happen in the fourth and fifth gears, it just seems to occur randomly.

The following error message is stored in the error log:

00570 017
Intake manifold pressure.
Rule difference.
Intermittent error.

00519 017
MAP sensor - G71.
Short circuit to positive.
Intermittent error.

Measurement block 10.

320 mg/H
979 mbar
989 mbar
0.0%

1090 mg/H
979 mbar
2570 mbar
100.0%

The installation (component diagnosis) of the VTG turbocharger was successful!

What could that be?
According to a Volkswagen master technician, the LLM is supposedly in good condition!

I suspect it's a faulty turbocharger, but I find that hard to believe because if that were the case, the problem wouldn't occur sporadically, would it?
Could it be that only the vacuum sensor is faulty? (I took it out and measured it once, and the resistance was 2.05 kOhms, which is too high?)
I don't want to start replacing parts randomly.


thank you in advance

Sure, here's the translation:

'Hello.'
Thomas.

hello,
How well can you handle your VW certification?
If I were you, I would borrow a completely new exhaust system from a Volkswagen workshop, install it, and see if the problem reappears!

00519 017
Intake manifold pressure sensor - G71.
Short circuit to positive.
Intermittent error.

Hello.

Necrite wrote:

00570 017 Intake manifold pressure. Rule difference. Intermittent error. 00519 017 MAP sensor - G71. Short circuit to positive. Intermittent error

.

Hi Thomas,

The most likely cause for both errors is a stuck VTG (Variable Transmission Gear).

Quote:

The employment (component diagnosis) of the VTG turbocharger was successful!

That doesn't necessarily mean anything; it can still occasionally glitch or freeze.
Please read the entry in the error database titled "stuck VTG..." before proceeding.

Quote:

Measurement block 10. 320 mg/H 979 mbar 989 mbar 0.0% 1090 mg/H 979 mbar 2570 mbar 100.0%

The 1090 mg at full load (at what RPM?) despite the 1.5 bar boost pressure could potentially indicate a real (very rare) defect in the area of the pressure sensor.

In the case of the AFN engine, it is integrated into the engine control unit (recognizable by the sand dune-shaped pressure hose leading to the engine control unit).
If there really should be something wrong, according to common repair practices, it would mean "new engine computer!"

Perhaps a stray piece of solder has become lodged between the positive terminal and the output of the pressure sensor within the engine control unit.
I would therefore remove the engine control unit, open it up, and take a look inside.
And if necessary, try to purchase a new pressure sensor and solder it in. The Bosch part number is printed on its casing.

Can you log the error message and post it here before translating?

First of all, thank you for the answers .
Sorry, I misspoke in my first error; it's actually 575...

I will check the charger adjustment again tomorrow and apply some copper paste.

The 1090mg/H reading was at 3rd gear, 3000 RPM, and the boost pressure of 2570 mbar is concerning to me. Since 2550 mbar is actually the maximum , and the full pressure is already reached at 3000 RPM...

'Something else I noticed is that the connector for the mass airflow sensor in the intake manifold was replaced shortly after the two cables from the wiring harness were separated. A new connector (with two thicker 1.5mm² wires, colored yellow) was then crimped on.'

I've only had the car for one week. Unfortunately, I didn't notice this problem during the test drive because I could only drive a maximum of 100 km/h, and the error 'fortunately' didn't occur then!

Could the short circuit after connecting to the positive terminal possibly be caused by incorrectly connected cables? What would happen if I temporarily connect the cables in reverse?

I will definitely give the salesperson a piece of my mind tomorrow!

Sure, here's the translation:

'Hello.'
Thomas.

Okay, sorry, I forgot, I can have the measurement block 11 read out tomorrow .

Necrite wrote:

What else I noticed is that the connector for the sensor in the intake manifold was replaced shortly after the two cables from the wiring harness were separated. Then, using crimp connectors, a new connector (with 2 thicker 1.5mm² wires [yellow color]) was connected. Could the short circuit after the positive terminal possibly be caused by incorrectly connected cables? What would happen if I temporarily connect the cables in reverse?

Hi Thomas,

Well, hmm... I only know the AFN wiring diagram with a pressure sensor in the engine control unit.

A pressure sensor in the intake manifold typically has at least 3 wires, while a combined pressure and temperature sensor usually has 4 wires.

"Only 2 wires can actually indicate a standard temperature sensor."

Okay, before we proceed any further, could you please describe exactly where the sensor is located, how many wires it has, and whether there's a thin hose leading to the engine control unit?

Hi,

Does the AFN actually have a 'magnetic valve for limiting boost pressure,' like the 1Z?
Then it's probably this one.
Because the error described is something I am familiar with from my own experience.

hi
I'm referring to the sensor/probe that sits in the lower pipe when you're standing in front of the engine; it's secured by a green metal clip. I believe this is the intake manifold pressure sensor, or am I wrong?

If I'm not mistaken, the AFN also has this valve, located on the far left side, slightly below the LLM.

If this is indeed the valve, why is it already producing 2.5 bar of boost pressure at 3000 RPM? Shouldn't it be limiting the boost pressure later?

Sorry, diesels are unfortunately not my area of expertise .

I should have kept the gasoline car ; it was simply easier to find and fix problems, or maybe I should have chosen diesel as a 'specialization' during my training .

Hi,

@necrite:
What's the point if the boost pressure is limited 'too late'?
Then it's already 'too late,' or not?

Okay, so...
A faulty solenoid valve usually causes the boost pressure to become dangerously high. To prevent this from causing damage, the emergency mode you noticed kicks in.

Try swapping them out.
A good workshop (yes, they are rare) will often do this as a test run for free. And as I said, the valve itself isn't expensive.

It was probably true that if it were to be limited too late, it would certainly not be engine-friendly .

I'll try to get a sample copy for now.

thank you very much

That one thing, however, makes me suspicious...
Why does this only happen in the 4th and 5th gear?

Hi,


That one thing, however, makes me suspicious...
Why does this only happen in the 4th and 5th gears?

1.) The excessively high boost pressure must persist for a certain period before the system switches to emergency mode.
2.) Because you accelerate through the first three gears very quickly with full throttle, nothing happens.
3.) It's only in gears 4 and 5 that you can really hold the accelerator down for a long time.

That's how I explain it.
Just like it was for you, it was the same for me. In third gear, you should still be able to reproduce the issue, starting around 3,700 RPM. However, since very few people drive that aggressively all the time, the problem only becomes noticeable in gears 4 and 5.

Necrite wrote:

I mean the sensor/probe that sits in the lower pipe when you're facing the engine, it's secured by a green metal clip; I think this is the intake manifold pressure sensor, or am I wrong?

Hi.

If it only has 2 connection cables, then it is definitely not a pressure sensor, but rather a temperature sensor.

Now that you mention it, it happened for the third time on Saturday while driving on the highway, at 3700 RPM. I was coming off the acceleration lane and wanted to quickly pass a truck, so I accelerated hard in third gear, and then it jerked or lost power. I shifted into fourth gear, and from there, the limp mode came back on because I was again around 3000 RPM...
Therefore, it's quite possible that he already went into emergency mode in the third set.
I will test it tomorrow .
Thank you again!

One more question?
Given that the valve is actually broken...
Why does the sensor indicate a short circuit to the positive terminal?
Is that also related to follow-up errors caused by excessively high boost pressure?

I'm referring to the sensor/probe that sits in the lower pipe when you're facing the engine; it's secured by a green metal clip. I mean, is this the intake manifold pressure sensor, or not?

Hi.

If it only has 2 connecting cables, then it is definitely not a pressure sensor, but rather a temperature sensor.

There are definitely only two cables, unless they forgot to connect one during the connector modification .
No, I did open the isolation point; it's only two cables.

I can take a picture of the sensor/probe you mentioned sometime if I have the opportunity.

Necrite wrote:

Given that the valve is actually broken... Why does the sensor indicate a short circuit to the positive terminal? Does that also have to do with follow-up errors caused by the excessively high charging pressure?

Hi.

The sensor output voltage increases with the boost pressure, approaching the operating voltage of approximately 5 volts. Therefore, under extremely high boost pressure, the engine control unit might incorrectly detect a short circuit to the positive terminal (although I'm not entirely certain about this).

If the intake manifold sensor only has 2 wires, you can skip taking a picture. It's the temperature sensor.

hello
I've now found the error, unfortunately it's not the valve, or only a sensor/sender .
It's the turbo itself that has failed.
It's good that the new regulations regarding warranties have been in place since January 1, 2002. Fortunately, I don't have to pay anything now; the seller has to bear the full cost because the defect was already present at the time of sale (with the burden of proof reversed for the first six months).
Now I just have to wait until the new turbo is available.
I will get in touch when the car is running properly again .

Thank you again for the help and assistance .