VW Bora ARL - rußt und ruckelt enorm unter Last | Posts 16+

What you intend to do is not productive.

Russ = too much diesel for too little air. So, if the diesel injection amount is normal, then there may be a lack of air.

Again:
/newuser.php

Now I haven't read it carefully again, how do the boost pressure, target and actual values behave when the problems are present?

Quote:

I haven't re-read everything carefully, how do the boost pressure, target and actual values behave when the problems occur?

It seems that the engine is trying to build up boost pressure, but it is not actually able to do so effectively (While the boost pressure curve increases with increasing RPM, it is very erratic). The system has already been overclocked, and even under full load, you can't hear any hint of a fan noise. (The log for this can be found in my first post).

I can still remember my colleagues two years ago, when the hose connecting the turbo (1.9 TDI ASZ) had a long crack. It made a very noticeable noise, even though the crack wasn't even 15mm long. And it didn't cause any noticeable hesitation or jerking either. Had significantly lost its performance.

Could a "grinding/clamping" compressor significantly impair or slow down the air volume?

Hello,

Quote:

It seems that the pressure is building up, but it can't actually

oh yes? Measurement block 10 that you have logged is for the location, and the load pressure control is a control loop!

Block 11 is requesting the data, as it shows the target value and the actual value of the charging pressure. It's all also in the instructions.

I am writing it for the 3rd time. Time:
/newuser.php

That's everything you need to solve your problem.

Using a relative pressure of a maximum of 1.3 bar is not very useful if you already have a relative pressure of 2 bar in the log file, and the target pressure for the engine is already 1.55 bar.

What do you want to prove with that? That the loading pressure system is approximately 70% of the normally prevailing pressure?
With this, however, you won't find any more gaps in the hoses.

As far as I can see, the engine control unit cuts off the fuel supply after the extreme increase in boost pressure (hard cut-off), and there is also another problem, which means that there is still not enough air in the engine.

For example, through a closing flap that closes automatically or an AGR that opens uncontrollably. Therefore, my suggestion to check the underpressure system.

Best regards, Rainer

I'm revisiting the three logs again.
a) In the log, "The synchronization angle, which fluctuates between two values, is causing issues."
b) In the log "Full load: third to fourth gear", there is a high load fluctuation (?) - 2988 mbar. The zero positions of the accelerator pedal and the desired torque occur when shifting gears or when moving the pedal. After the initial start, the engine runs within the specified limits.
c) In the log "Full load: 3rd to 5th gear", you can again see the gear changes based on the pedal position. The engine is running within the smoke limit.

a) I am surprised by the behavior of the synchronization angle, but I have no experience with PD.
b) and c): First, a verschandeln flight "Full throttle, 3rd to 5th gear only, using only engine speed, throttle position, and smoke reduction; Air mass flow rate target, actual air mass flow rate, boost pressure target, actual boost pressure.
hg
Herbert

AGR could be temporarily closed. I'm not sure whether the access door is operated by vacuum or electrically...?

Is the underpressure system 100% functional? Also, the line from the auxiliary pump to the brake booster, remove and inspect, often there are cracks on the bottom.

Hi,

The pressure is building up too high, either the VTG is difficult to move, the ventilation from the underpressure system is blocked, the solenoid valve is defective, or there is some leakage in the underpressure hoses.

The closing door also sometimes operates independently, and this one works with vacuum pressure.

Both of the links I have posted previously, there are links to instructions, including a guide to the vacuum system and a fault table.

Hi, Rainer

Good evening everyone,

I hope everyone is doing well at that time

In the past, I have also followed some of the tips again.

Before, the displayed pressures in the log files are actually absolute values (including ambient pressure)? The "2 bar" charging pressure from my previous logs should correspond to an actual pressure of 1 bar in the pipe, or am I mistaken?

Nevertheless, the pressure charging system was checked again (1.5 bar // 2 minutes). The result: Absolutely sealed. There was absolutely nothing revealed at any point.

Furthermore, each individual vacuum hose was inspected, and each hose was found to be completely airtight. There were no cracks, no holes, or any other damage. The vacuum hose from the auxiliary pump to the brake booster was also replaced. - No difference.

The VTG is running smoothly, with no issues. Move to the final position and return.

The AGR valve is also not sticking. The valve itself is also relatively clean / not excessively carbonized. When I checked the MWB 3 again today with the engine warm, the values were consistent.

The suction valve also remains consistently open. To be absolutely sure, I've disabled them for a test drive, and the problem persists.

The only thing that I noticed today is that the symptoms appear more or less intensely (regardless of engine temperature, etc.). That is, sometimes the shaking under load is so strong that acceleration is hardly possible, and everything in the car starts to rattle. After time X, the car accelerates better on the same route and with the same accelerator position, and the "jerk" feels only about 50% as strong.

Furthermore, I also made two trips with the MWB 11 today.

Engine warm, full load, from the third gear.

During a drive, I unfortunately came across a "Continue" button once, which slightly elongated the trajectory. The second run should look a bit better.

The first log looks very strange in the direct "Should" vs. "Is" comparison. In the second stage, the boost pressure is already holding better at the target level, but it still feels very nervous.

Best regards, Timm

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.

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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