Zu wenig Ladedruck <2000U/min, aber keine Ahnung warum | Beiträge 32+

Sven@G4H hat folgendes geschrieben:

However, another factor against a clogged catalytic converter is that it runs at 195 km/h according to the speedometer, which should definitely be noticeable!

Depends on the specific case (how clogged it is). Vmax measurements on the road are not really useful for performance assessments, as it is difficult to adequately account for wind and gradients.

Zitat:

I've now connected the LDA to the air intake.

Finally! :mrgreen:

Zitat:

If I only run on half gas and do so at under 2000 RPM, does the gauge not show a significant drop? Could this perhaps indicate a leak in the intake area, or what do you think?

That is actually quite unusual. For example, our ALH Ibiza already shows a drop of several tenths of bar in the intake (this would require further investigation) when rolling on a flat surface at 100 km/h (~ 1/3 gas?).

Hi,
there are some initial updates. I've now reactivated the AGR and, as you can see, the boost pressure is building up at earlier engine speeds, but the acceleration still doesn't convince me; there's simply a lack of "bite"! I'll now take some logs without the AGR and then report back!

-mFg-

Just finished testing the drain pipe pieces, the air intake is 100% airtight! It even holds almost 2 bar!

Now, a silly question: when I let the fuel injectors cycle, the guy said they were okay, the worst one had 195 bar and the best one 205 bar! The spray pattern is great and there's no dripping! What's the maximum pressure difference allowed between the injectors?

-mFg-

Hi Sven,

I don't know of any exact wear value for the spraying pressure or differences. However, based on experience, I can say that deviations of +/- 5% generally don't require adjustment of the nozzles.

But let's get back to your problem. I've been following this thread with interest. Based on your measurements, it's clear that your air path is in perfect order, as it should be. Even with significantly more boost at 2000 RPM, you wouldn't notice a significant increase in torque, as you're already running at 1300 RPM and from there, the boost only becomes the third factor in torque generation.

You're probably right that the boost build-up is significantly delayed. However, this behavior is extremely gear/environment dependent. In 1st gear, you may never reach the target value, but in 5th gear, you can already reach it at 1300 RPM, and the situation changes again depending on the slope or altitude.

In other words, when evaluating and comparing the boost build-up, the gear/time is always relevant - so always specify it.

It is clear to you that the TDI engine, due to its torque limiting curve, has less power available below 2000 rpm, and therefore will never have the same "bite" as it does at its maximum torque. However, an assessment in this case is always extremely subjective and difficult. If, however, you are certain that you have less power in comparison, and that all components are in good condition (as your measurements show), and that the maximum power is also achieved, then the only possible cause is the amount of fuel injected at small injection pressures and low engine speeds.

It seems your injectors are okay, so the only remaining issue is probably a slight reduction in fuel delivery at low speeds/injection pressures.

What is the fuel requirement at idle with water/oil around 90°C without air conditioning or other consumers? This is something we could investigate further.

Otherwise, the only other thing that comes to mind is efficiency – how is the compression/camshaft performing?

But I think you won't find a solution in the air intake.

Good luck!

bafische hat folgendes geschrieben:

It seems your injectors are okay, so the only remaining possibility is a lean condition at low RPMs or injection pressure. What is the fuel requirement at idle with water/oil at ~90°C without air conditioning or other consumers? This is where we might be able to find some information.

Hi bafische,

if this results in an "overly lean" MSW setting, perhaps due to an excessive correction during a failed MSW adjustment?

IMO, this is completely plausible -> then Sven should actually only check the data of the MWB 1 while the engine is idling. . . . ?

Hi,
The camshaft looks very good, I haven't measured the compression yet, but I've heard from a mechanic that there are often creeping connecting rod failures in TDIs, the injection timing was too early after the timing belt replacement, I unfortunately don't know how long it was too early, but I will definitely do a compression test anyway!

Okay, here's the translation:

I'm going to log the MWB1 in idle mode. I sometimes feel that not enough fuel is being injected, as I can't seem to get the car to misfire. I have never seen any smoke or anything else coming from the exhaust. I also had someone drive behind me while I was revving the engine, and they didn't see any smoke or anything else, even with the engine revving at full throttle.

Hi,
here is a log of measurement block 1 at approximately 80°C coolant temperature during idle! I have also logged the engine speed control.
Can you draw any conclusions from this?

http://www.geocities.com/sveng4h/LeerlaufMWB1.xls

-mFg-

Sven@G4H hat folgendes geschrieben:

Here is a log of measurement block 1 with a coolant temperature of approximately 80°C during idle! I also logged the engine speed control. Can you draw any conclusions from this?

For me, everything looks OK here... if 10 mg/stroke had been indicated, then Bavarian's suspicion could have been confirmed.

However, it is possible that your loader is not optimally set up, even though the symptoms only partially match IMO... please check the MWB 11 on the default settings and log for approximately 40 seconds.

EDIT: I just found your values in
/viewtopic.php?t=10428&postdays=0&postorder=asc&start=36
The almost 100 mbar could possibly explain the problem. Our ALH-Ibiza has consistently shown readings well over 200 mbar - although with the uncertainty factor of the gas foot.

A technical article on adjusting VTG chargers will be published soon. It might be worth trying to readjust the VTG setting. . .

Sven@G4H hat folgendes geschrieben:

Hi, Here is a log of measurement block 1 at approximately 80°C coolant temperature during idle! I have also logged the engine speed control. Can you draw any conclusions from this? http://www.geocities.com/sveng4h/LeerlaufMWB1.xls -mFg-

As Ulf said, 3mg/stroke during idle - this suggests a slightly fat pump. The car should therefore run better than others. My ALH has 4.5mg/stroke during idle.

The fact that the car doesn't even accelerate properly doesn't necessarily mean there's a problem with the performance or fuel injection. If all the components are in good condition and within tolerance, visible smoke, especially with the ALH, shouldn't be present.

The data doesn't seem to match the problem you've described. Perhaps a compression test would provide some information.

Since the engine control unit is original, there's no chip tuning or box installed, correct?

As a last resort, I think replacing the hydraulics is disproportionately expensive.

Hello,
no, it's not chipped, and it's not a 10-cent unit or anything!

I also repeated the test mentioned by Ulf in the basic settings mode earlier, and the maximum difference at 1400 rpm is 100 mbar! But as I said before, the charger is brand new. I received a new one under warranty because of the burnt-out VTG. The problem already existed with the old charger when the VTG was still intact, so I would have ended up with two chargers that were incorrectly adjusted!

@bafische
I now see a compression test as essential and will be taking care of it next week.
What do you mean by "replace the hydraulics"? Which hydraulics?

-mfg-

Sven@G4H hat folgendes geschrieben:

The problem also existed at the time when the VTG was still intact, so I would have ended up with two incorrectly adjusted loaders anyway!?

I also think that is very unlikely.
Did you have the 1400 rpm only when "VTG OFF" (then it would be around 100 mbar normally), or did you re-adjust the 1400 rpm again after each switch using the gas pedal?
Then 100 mbar would be quite low, because our Ibiza ALH produces well over 200 mbar.

It might still be the pump: please provide the lower and upper RWG target values -> presumably MWB 19.
You can find the target values in the "Target Values" article (they are almost all the same for VP37 4Zyl).
If your values are close to the tolerance limits, it might be possible to solve the entire problem by adjusting the RWG and MSW.

A pump that maintains a consistent flow rate of around 3 mg despite high operating performance, without experiencing any jerking or fluctuations in speed, seems to indicate a very efficient setting, which in turn results in a relatively sluggish operation of the pump.

Hi,
ok, I have the target voltage values for the start and stop control path, but only for idle. Is it sufficient if I only check the values when the engine is idling?

For the load check, I simply activated the basic settings and started the log. Then I got into the car and brought the RPM to around 1400 U/min. I then checked that the RPM always remained constant, regardless of whether it was ON or OFF. The maximum value was 100 mbar!

I don't have any stuttering problems, but I've been noticing it for a while and haven't been able to identify the cause!

-mFg-

Sven@G4H hat folgendes geschrieben:

I have the voltage specifications for the control lever range for starting and stopping, but only for idle. Is it sufficient if I only check the values when the engine is idling?

Yes, because the check runs with the engine still idling, i.e., before starting.

Therefore, according to my understanding, it is sufficient to briefly turn on the ignition.

Zitat:

During the load check, I simply activated the default settings and started the log. Then I got into the car and brought the RPM to around 1400 RPM. I then checked that the RPM remained constant, regardless of whether the system was ON or OFF, with a maximum of 100 mbar!

Ah, yes. . . At our ALH, the speed drops from 1400 rpm to approximately 1260 rpm during the OFF->ON transition, and I had to manually increase it by about 140 rpm using the throttle.

If your speed doesn't decrease so significantly, it could indicate that your VTG isn't closing as much . . . this could potentially be a (partial) cause of your problem.

However, a more "conservative" pump adjustment would still be better overall.

Hello,

The engine speed also dropped by about 100 rpm during the boost check, which I then compensated for with the accelerator!

I just read out MWB 19. If I understand correctly, I don't need to start the engine? Then I can read the following values:

MWB19
Start Stop
0.74V 4.48V

Target values
Start Stop
0.5V-0.97V 4.15V-4.74V

This actually looks okay to me, or?
What do the 3mg in idle mean? Is it a rich or lean fuel pump setting?

-Best regards-

Sven@G4H hat folgendes geschrieben:

I just read out the MWB 19. If I understand correctly, I don't need to turn the motor on? Then I can read the following values! MWB19 Start Stop 0.74V 4.48V Target values Start Stop 0.5V-0.97V 4.15V-4.74V This actually looks okay to me, right?

Yes, it does to me too.

If your values, for example, had been 0.52 and 4.72 V, that would have meant that the pump was delivering relatively little at full power, and while the car was running cleanly, it was probably also running a bit sluggish.

But this way, we can probably forget about the RWG setting as a performance and LD killer.

Zitat:

What do the 3mg in idle actually mean? Is it a rich or lean pump setting?

More likely a rich setting (I know, "rich" is the wrong term when talking about diesel... ), which often also leads to rough running.

So bleibt am Ende hauptsächlich ein (halb) verstopfter Auspuff / Kat übrig... Ist der Ansaugkrümmer sauber, also nicht durch AGR-Drosselung verstopft?

Ich würde den VTG-Anschlag aber noch nicht ganz aus den Augen verlieren, aber eine Justage nur aufgrund der ungenauen Gaspedal-Methode bei der Grundabstimmung wäre etwas gewagt.
Hast Du ein Log von der Grundabstimmung gemacht? Dann könnte ich das mal mit unserem ALH vergleichen.

Hi,
Yes, the intake paths are 100% clear. I have completely disassembled everything, including the intake bridge, and cleaned it!

Here is a log from the LAder check, but the 1400U/min was entered rather sloppily by me! I will try to get a more accurate log from you tomorrow!

http://www.geocities.com/sveng4h/LDDifferenz.xls

-mFg-