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

Sven@G4H wrote:

However, there's also an argument against a clogged catalytic converter, as the car is running at 195 km/h according to the speedometer; shouldn't a clogged catalytic converter be noticeable then?

It depends on the specific case (how clogged it is). Maximum speed measurements taken while driving are generally not very useful for determining performance because it's difficult to adequately account for wind and road gradient.

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I've now connected the LDA to the intercooler,

Finally!

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If I only drive with partial throttle and the engine speed is below 2000 RPM, does the gauge not move at all? Perhaps this indicates a leak in the charge air system, or what do you think?

That's actually quite unusual. For example, our ALH Ibiza already shows several tenths of a bar of manifold absolute pressure (MAP) while idling on level ground at 100 km/h (~ 1/3 throttle), which I should probably investigate further.

Hi,
"I have some initial news: I've now reactivated the EGR system, and it seems that the boost pressure builds up at lower RPMs. However, I'm not entirely convinced by the acceleration; it's just lacking that extra punch! I'll run some more logs without the EGR system this time, and then report back."

-Sincerely-,

I just finished testing the drain pipe connections, and the intercooler system is completely airtight! It can even hold almost 2 bar of pressure!

Okay, one more silly question: When I had the injectors tested, the guy said they were okay. The worst one had a pressure of 195 bar, and the best one had 205 bar! The spray pattern was great, and there was no dripping! What is the acceptable difference in pressure between the injectors?

-Sincerely-,

Hi Sven,

"I don't know the exact wear values for injection pressure or the differences between them. However, based on my experience, I can say that deviations of plus or minus 5% usually do not require nozzle adjustments."

But getting back to your problem, I've been following this thread with interest. Based on your measurements, it's safe to say that your intake system is in perfect order, which is how it should be. Even if you increased the boost pressure even further below 2000 RPM, you wouldn't notice a significant increase in torque, because you're already driving in the powerband from 1300 RPM onwards, and from that point on, the turbocharger and boost pressure only play a minor role in building up torque.
You're right that the turbocharger builds boost significantly slower. However, this behavior is extremely dependent on the gear and the environment. In first gear, you may never reach the target boost pressure, while in fifth gear, you can achieve it at just 1300 RPM. And with a downhill slope or an uphill gradient, or at higher altitudes, everything changes again.
In other words, when evaluating and comparing boost pressure build-up, the gear and time are always relevant – so be sure to include them in your analysis.

You are certainly aware that our TDI engine produces less power below 2000 RPM due to its torque curve, and therefore will never have the same "bite" at those lower speeds as it does at its peak torque. However, any assessment here is always extremely subjective and difficult. If you are certain that you have less power compared to before – and all involved components are in good condition (as your measurements show), and the maximum power is also being achieved – then the cause could almost certainly be related to the fuel injection quantity at low injection pressures or engine speeds.

Your injectors seem to be fine, so the most likely cause is a lean condition in the pump at low speeds or injection pressures.

What is the coolant flow rate required when the engine is idling, with water/oil temperatures around 90°C, without the air conditioning or any other accessories running? There might be something interesting to discover here.

Besides efficiency, I'm also wondering about compression and camshafts. How do those factors play a role?

But I don't think you'll find a solution in the air.

Best of luck going forward.

bafische wrote:

Your injectors seem to be fine, so it's likely that the problem is a lean condition in the pump at low speeds or injection pressures. What is the coolant flow rate required at idle with water/oil temperatures around 90°C, without the air conditioning or any other consumers running? There might be something interesting to uncover here.

Hi Bavarian,

Could it be that the settings are too conservative, perhaps as an overcorrection when "undoing" a previously unsuccessful attempt to optimize the MSW (Master Slave Window) configuration?

In my opinion, that would be perfectly reasonable. Then, Sven would only need to check the data from the MWB 1 while the engine is idling and warmed up... ?

Hi,
The camshaft still looks very good. I haven't measured the compression yet, but I heard from a mechanic that piston ring wear is more common in TDIs. The injection timing was too advanced after the timing belt change, and unfortunately, I don't know for how long it was off. However, I will definitely have a compression test done.

Okay, I'm going to take a log of the MWB1 at idle. I sometimes have the feeling that not enough fuel is being injected because I just can't get the car to produce any soot. I've never seen any smoke or anything like that coming from the exhaust. I even had someone follow me and observe, and according to their report, there wasn't a single puff of black smoke, despite very rough running.

-regards-

Hi,
Here's a log from measurement block 1 at approximately 80°C coolant temperature, while idling. I also logged the idle control system.
Can you draw any conclusions from this?

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

-Sincerely-,

Sven@G4H wrote:

Here's a log from measurement block 1 at approximately 80°C coolant temperature, while idling! I also logged the idle speed control. Can you draw any conclusions from this?

To me, everything looks fine here... If it had shown 10 mg per dose instead, then "bavarian's" assumption might have been correct.

It's possible that your charger isn't optimally configured, even if the symptoms you're experiencing only partially match what I would expect... please go to the "basic settings" section in the main control panel (MWB 11) and log the data for about 40 seconds.

"EDIT: I just entered your values into..."
/viewtopic.php?t=10428&postdays=0&postorder=asc&start=36
found.
The pressure of approximately 100 mbar might potentially explain the problem. Our ALH-Ibiza produced a reading significantly above 200 mbar, although that also included the uncertainty factor of the gas pedal.

A technical article on the installation of VTG chargers will be published soon. It might be worth trying to readjust the VTG connection.

Sven@G4H wrote:

Hi, Here's a log from measurement block 1, taken at approximately 80°C coolant temperature while idling. I also logged the idle control system data. Can you draw any conclusions from this? http://www.geocities.com/sveng4h/LeerlaufMWB1.xls -mFg-

As Ulf already mentioned, 3mg/stroke in the LL (likely referring to a fuel injector setting) suggests a somewhat richer mixture. This would mean the car should perform better than others. My ALH engine has 4.5mg/stroke in the LL.

The fact that the vehicle doesn't produce any smoke doesn't necessarily indicate a lack of power or insufficient fuel injection. If all components are functioning correctly and within acceptable tolerances, visible smoke, especially in ALH engines, should not be present.

The data doesn't seem to match the problem you described, but perhaps a compression test will provide some insight.

Is the engine control unit (ECU) original, or has it been modified with a chip tuning device or external module?

I believe that replacing the hydraulics should be considered a last resort and is disproportionate in this situation.

Hello,
No, he is not microchipped and he also doesn't have any kind of tag or identification device on him.

I also ran the test mentioned by Ulf in the basic settings mode a little while ago, and the maximum difference at 1400 RPM is only 100 mbar! But as I said, the turbocharger is brand new; I received a replacement under warranty due to the sooty VTG. This problem also existed with the old turbocharger when the VTG was still intact, which means that I would have had two incorrectly adjusted turbochargers right from the start?

@bavarian
I now consider a compression test to be essential, and I will take care of it next week.
Was meinst du mit "Hydraulik tauschen"? Which hydraulics?

-regards-

Sven@G4H wrote:

The problem also existed with the old loader at the time when the VTG was still intact, so I would have caught two misaligned loaders right away!?

I also find that very unlikely.
Did you only see the 1400 rpm during the load test when "VTG OFF" was selected (in which case, approximately 100 mbar would be normal), or did you have to re-adjust it to 1400 rpm each time you switched modes using the accelerator pedal?
Then 100 mbar would be quite tight, because, as I said, our Ibiza ALH produces well over 200 mbar.

It could still be related to the pump: please post the lower and upper pressure setpoints for the RWG (Relief Valve Group) -> probably MWB 19.
You can find the target values in the dedicated article on target values (most of them are the same for VP37 4-cylinder engines).
If your values are close to the tolerance limits, the entire problem could likely be solved by adjusting the RWG and MSW settings.

A pump that, despite a displayed LL (low lubricant) quantity of only 3 mg and high mileage, doesn't exhibit any surging or hesitation at low RPM, almost suggests a very economical overall setting. This, in turn, likely means a somewhat weak boost from the turbocharger...

Hi,
Okay, I have the voltage setpoints for the throttle position based on start and stop conditions, but only for idle. Is it sufficient to just check these values at idle?

During the charger check, I simply activated the basic settings and started the log. Then, I got into the car and brought the engine speed up to approximately 1400 RPM. I then observed that the engine speed remained constant regardless of whether the system was in "ON" or "OFF" mode! The maximum pressure reached was about 100 mbar.

I haven't experienced any jerky movements, and I've been paying attention to it for a while now, but I can't find anything wrong.

-Sincerely-,

Sven@G4H wrote:

I have the voltage setpoints for the throttle position during start and stop,

but only for idle. Is it sufficient if I only check these values at idle?

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Yep, because the check is performed while the engine is still off, before it's started. Therefore, as far as I know, it is sufficient to briefly turn on the ignition.

During the charger check, I simply activated the basic settings and started the log, then got into the car and brought the RPM to approximately 1400 RPM, and then checked that the RPM remained constant regardless of whether it was ON or OFF! The maximum pressure reached was 100 mbar! }

Okay... In our ALH engine, the RPM dropped from 1400 to approximately 1260 during the transition from OFF to ON, and I had to use the accelerator pedal to regain those roughly 140 RPM.
If the engine speed doesn't drop as significantly in your case, it suggests that your variable geometry turbocharger (VTG) isn't closing as much... this could potentially be a (partial) cause of your problem.
However, a "more efficient" pump adjustment would still be generally better.

Hello,
During the loader check, the speed also dropped by approximately 100 RPM, which I then compensated for by adjusting the throttle.

I just read out the data from module MWB 19. If I understood correctly, you don't need to start the engine to do this? Then I can read the following values!

MWB19
Start Stop
0.74V 4.48V

Setpoints.
Start Stop
0. 5V - 0.97V 4.15V - 4.74V

It looks fine to me, doesn't it?
What do the 3mg readings at idle indicate – is it a rich or lean pump setting?

-regards-

Sven@G4H wrote:

I just read out MWB 19, and if I understood correctly, you don't need to start the engine to do this!? Then I can read the following values! MWB19 Start Stop 0.74V 4.48V Setpoints. Start Stop 0. 5V - 0.97V 4.15V - 4.74V It looks fine to me, doesn't it?

Yes, for me too.

If your values were, for example, 0.52 and 4.72 V, that would mean the pump is delivering a relatively small amount of fuel at full throttle, which could result in low emissions but also likely cause the car to feel sluggish.
But in that case, we can probably forget about the RWG setting as a performance booster or latency reducer.

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What do the 3mg at idle mean, is it a rich or lean fuel injection setting?

It's more likely rich (I know that's the wrong term for diesel engines...). This often also leads to jerking problems.

So, in the end, it mostly boils down to a (partially) clogged exhaust system/catalytic converter... Is the intake manifold clean, or is it constricted by deposits from the EGR valve?

While I wouldn't completely dismiss the possibility of a VTG issue, an adjustment solely based on the inaccurate throttle method used during the initial setup would be quite risky.
Did you create a log of the initial settings? If so, I could compare it to our ALH system.

Hi,
Yes, the intake passages are completely clear; I disassembled everything, including the intake manifold, and cleaned it all thoroughly!

Here's a log from the charger check, but the 1400 RPM setting was entered quite carelessly this time! I'll try to get a more accurate log tomorrow.

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

-Sincerely-,