VW Bora ARL - rußt und ruckelt enorm unter Last | Posts 24+

Hi,
Unfortunately, this only shows the boost pressure. Initially, there is a significant overboost, but then the response becomes sluggish, and it is only measured in the upper RPM range. The regulation is not clear, but I wouldn't be looking for the root cause of the problem there.
Please perform the measurement as I suggested. And start with 1500 min-1, and then return to that value when switching, or directly switch from the 3rd to the 5th. Go for a walk.
hg
Herbert

Hi,

The nearly 3000mbar in the log is absolute pressure, which corresponds to approximately 2 bar relative to the ambient pressure. To be expected at full throttle is approximately 1.55 bar relative.

"It's been there at the top of the topic for ages, so do something about it."
Please refer to /newuser.php, especially the section with the links to the articles.

Hi, Rainer

Good evening everyone,

Just then, I had another opportunity, which I used to make a few Log trips with the (hopefully) suitable MWB. Air mass - I unfortunately couldn't find the "TARGET" value.

Once again, the vehicle surprised me.

I expected the usual jerking and shuddering (which could always be expected, even when the engine was warm), but it happened right from the very first start.

Third gear, 1500 rpm, full load - after what felt like 3 seconds, the car went into limp mode. "This was the first time a fault code was entered."

Here's an excerpt from the car scan:

Address 01: Engine Electronics Label file: DRV\038-906-019-ARL.lbl
Part Number: 038 906 019 KG
Part Number: 1.9L R4 EDC G400SG 4900
Encoding: 00002
Operating Number: WSC 01266
VCID: 66944C29117587D753A-4B3C
VWZ7Z0C7868482

1 Error found:
17965 - Charging Pressure Control
P1557 - 35-00 - Limit exceeded
Readiness: 0 0 0 0 0

This has never happened before, and since my last workshop visit to inspect all the hoses, etc., I haven't touched the vehicle anymore.

Okay, error code deleted, engine restarted, and the procedure repeated. Result: Again, after a short run in third gear - failure mode. Re-attempt with error code.

Back to zero, back on the highway, this time starting in fourth gear: He was running. Although it hadn't been performing at its usual level for a while, the boost pressure was maintained, and it "accelerated" to 180 km/h without the usual extreme jerking (it felt more like a pulsating vibration, similar to that of an unbalanced tire).

This whole thing was repeated again, and this time, the desired pressure was also maintained. Nevertheless, upon arriving home, the aforementioned issue occurred again. Fault in the control unit.

It strongly resembles the N75 valve. Everything else has already been checked. The VTG felt very smooth when I checked it with the hand pump under the car; there was sufficient vacuum at the valve, and all the hoses were intact.

In the attachment, I have uploaded the log file and the Autoscan.

Quote:

Has been a topic for ages, so do something about it. Please refer to /newuser.php, especially the section with the links to the articles.

I have read it thoroughly and carefully. I have already checked, renewed, or cleaned many things from it. Slowly, only "minor things" like checking the fuel pressure on the tandem pump remain.
I even purchased the self-study program from VW for the PD element in addition to this, in order to better understand the relationship between the individual sensors and the injection logic (especially the inner workings of the PD element).

Best regards, Timm

Hi,
In the areas without a limp mode, it appears as if there is a lot of boost pressure with little air mass. This would then include measures such as limiting smoke, purging, and possibly even an emergency shutdown due to excessively high pressure.
The values for the air mass should be in the range of up to 1250 mg/stroke for the 150 HP engine at high power.
(When testing, you should aim to observe the values at around 1500 min-1 multiple times - see my previous post.) Then, you draw the torque curve along!
Possible causes, as far as I can currently identify:
- LMM faulty or defective; wiring may be damaged;
- Faulty or defective load cell sensor; wiring is also faulty;
- Blockage between the pump and cylinders, e.g. Intake manifold or intake channels clogged, also with cleaning cloths;
- Throttle valve closed or partially closed (also due to faulty wiring).
hg
Herbert

Good evening everyone,

Quote:

Possible causes, as I can currently think of them: - LMM is faulty or defective; wiring is also faulty; - Faulty or defective charging pressure sensor; Wiring is also faulty; - Blockage between the cylinder and the pump, e.g., intake manifold or intake channels clogged, also with cleaning cloths; - Throttle valve closed or partially closed (also due to faulty wiring).

The LMM was replaced 100km ago (original Bosch replacement part from the certified dealer).

I now also suspect the load sensor.

I should take a closer look at the intake manifold from the inside. I would, however, be less inclined to believe that.

Is the throttle valve meant to be the intake valve? I had already blocked that one for testing purposes. The problem, however, still persisted.



Out of curiosity, I wanted to do another log drive today with the AGR valve disconnected.

What immediately caught my attention: The car started incredibly poorly. He played the organ for about 3-4 seconds before it rang.

But I was able to complete a pretty good run, where the vibrations in the suspension are clearly visible.

For example, if I maintain a speed of 2500 rpm in second gear, I notice that the car "jerks" or "stutters." It's as if some valve is opening and closing intermittently. One can even see it by looking at the rev counter, which is fluctuating.

The first run ended directly in emergency mode. In the second run, I wanted to keep the engine speed as low as possible. The third and final run most likely reflects the problem. From second 34, the car then drove relatively okay. But it was still very shaky and jerky.

Maybe I'll just replace the load pressure sensor as a precaution. While the values only deviate by 10 mbar when the car is stationary. But somehow, it surprises me that with such low air mass, a boost pressure of around 2 bar should be achieved so quickly.

Have a wonderful evening.

Best regards, Timm

If you hang all the measurements from consecutive trips together, it becomes very confusing. You can certainly use new filenames.
Do you notice that, based on the data, you are always at 100% on the accelerator pedal? So, presumably in the highest gear on the highway? Where is the point at which to maintain a certain RPM? Continuing this argument is pointless.
One can see that there is not enough air for the achieved boost pressure, driving at the edge of the smoke, and soot formation. This can already be narrowed down to the suction path after the pressure sensor or the pressure sensor itself.
How did you measure the pressure when pressing?
hg
Herbert

Hello everyone,

Quote:

If you hang all the measurements in a row, it will become very confusing. You can certainly use new file names.

I completely agree with you. I mistakenly assumed that the filename would automatically be incremented with a numerical index.

Quote:

Have you noticed that, according to the data, you are always at 100% on the accelerator pedal? So, presumably in the highest gear on the highway? Where is the place to maintain a speed?

Exactly, the largest deviations should probably be seen at 100%. Maintaining the RPM was not visible in the last log.

Quote:

Due to insufficient air intake for the achieved boost pressure, driving near the smoke limit, and fouling. This could be narrowed down to the suction path after the pressure sensor or the pressure sensor itself.

Can a faulty pressure sensor cause a symptom such as, for example, excessive soot formation?

I have checked the intake again for dirt or other contaminants. However, everything is in perfect condition. Is the question whether it is worthwhile to order another new LMM, in the hope that it will improve the measured air volume?



I would like to take a closer look at the intake manifold with a scope in the next few days (Unfortunately, a complete removal is not possible due to the AGR cooler and other components).

Furthermore, I also made a few Log runs (this time separately ) at a more moderate speed. Notably, in the fourth Log, the boost pressure is significantly lower than the target value. This was something I hadn't noticed before. Otherwise, he only shows the usual peak values up to 0.5 bar above the TARGET.

Best regards, Timm

Hi,
You won't get any closer to the problem by simply having these types of driving records. To determine the difference between the target and actual boost pressure, you would need the target and actual air mass, as well as any mass flow limits.
But I would like to emphasize another way to you. In particular, take a close look at the intake manifold and the intake channels, check the electrical lines and connections, and check the boost pressure gauge in comparison with a pressure gauge outside. The first, because it looks like it's very poorly filled with air, despite the high boost pressure.
hg
Herbert

Good evening everyone,

It's been a long time since I've had a chance to speak.

Inzwischen, the following has also been done to the car:

- Intake manifold inspected (Found to be completely in order.) Minimal deposits - approximately 1.5mm in diameter).

- The N75 solenoid valve was replaced.

- The boost pressure sensor has been replaced.

- All Ladeluftschläuche wurden zusammen mit den Dichtungen und Halteklammern ausgetauscht (Beachten Sie, dass jede Halteklammer am ARL eine andere Teilenummer hat, mit Ausnahme derjenigen, die am LLK befestigt sind).

- New OEM VW diesel filter (Due to starting problems after prolonged idling).

Problem: Everything remains essentially the same as before. After changing all the hoses, it feels "softer" in some ways, but it still produces black, gritty oil, jerks, and only has half the original power.

Today, I made some more recent log flights (See Appendix). The air mass seems to be suitable. The boost pressure seems to be holding better to the TARGET characteristic, but it keeps cutting out or remaining just below the TARGET.

We tested the VTG locking mechanism on the lifting platform again and it didn't seem to be holding properly. The VTG gymnastics went smoothly.

{OTHER_OPTIONS} wouldn't occur to me either. Everything else has been completely new - with approximately 90% original VW parts.

Should it be the turbo that's the problem, the car will be scrapped, and I'll get a new one.

If anyone notices something in the log entries that I may have missed, I am open to suggestions

Best regards, Timm

Hello,

The air mass value is also too low for a 2300 mbar boost pressure, so I suspect that the AGR valve is not closing or is opening due to incorrectly connected vacuum hoses, even though it should not. Also, also auch the throttle valve (parking valve) check, in normal operation, this valve is always completely open in the engine.

Best regards, Rainer

Hello Rainer,

Thank you for your feedback.

I have already disabled the AGR valve, so nothing should be able to pass through it anymore.

I re-blocked the suction valve earlier (disconnected and closed the vacuum hose) and went for a longer ride. Unfortunately, without success.

On a particularly steep road, he entered emergency mode at less than 75% load.

P1557 - Limit exceeded

Sounds like a sign of a stuck VTG (for whatever reason).

I exclude the possibility of incorrect hose connections. I can assure you of this. I had thoroughly labeled them before checking, and some of them only fit into their original position once.

Could a turbine wheel with excessive play be so strongly braked within the housing that it can draw in too little air? So far, I haven't encountered a case like this before.

Best regards
Timm

Herbert wrote:

The first, because it looks like there's a lot of air in the cylinder, even though the boost pressure is high.

If you can rule out errors on the intake side, then the exhaust side remains. If something is leaking, the filling won't fit properly either.

Quote:

I have already shut down the AGR valve, so nothing should be able to pass through anymore.

What about connecting the AGR (Exhaust Gas Recirculation) to the turbocharger? Exhaust manifold: Is it sealed properly and not warped or loose?

guste100 wrote:

Because it looks like there's a lot of air in the cylinder, even though the boost pressure is high. Herbert wrote: If you can rule out errors on the intake side, then the exhaust side remains. If something is sealed, the filling won't fit anymore.

I have already completely disassembled and checked the intake. From the beginning (intake behind the grill) to the fresh air side of the turbo, everything is clear. Even the air filter is new.

Then I will take a closer look at the alley side again. The muffler still sounds very good ("exhaust test"), and when I hold my hand against the muffler, I can also feel the pulsating exhaust pulses.

Quote:

What about connecting the AGR (Exhaust Gas Recirculation) to the turbocharger? Are the exhaust manifold seals tight and not warped or loose?

I haven't disconnected the connection directly from the manifold yet. But it has no leaks.

The exhaust pipe is definitely firmly screwed on. There are no soot stains around it. Therefore, I would not assume that the manifold is warped.


Can a camshaft wear so much that the valves don't open far enough to ensure reasonable cylinder filling?

Also, even the hydros could be affected. It all comes down to the same thing. Read!
https://www.yumpu.com/de/document/view/23049048/schwierige-diagnose-an-einem-tdi-motor-zawm

The cylinder head cover on the engine can be removed very quickly and easily.