Steigender Leerlaufverbrauch. Kennt das Jemand? | Posts 16+

serdarg wrote:

Okay, the correction is normal. Only before, the value became smaller, and now it's becoming higher. What about the boost pressure, the actual and target values? They only become equal at 2000-2500 rpm. At idle and up to approximately 2000 rpm, the actual boost pressure is 50-80 mbar lower than the target value. And at high engine speeds, the actual LD exceeds the target value. As I said, sometimes it's so much that the MSG switches to emergency mode.

Speculatively, if the engine is not properly adjusted, something might be so severely misaligned that a disproportionately large amount of the energy released during combustion goes into the exhaust gases: this could explain the excessively high LD, and the reduced efficiency could also explain the increased fuel consumption or the lack of power.

However, I'm not familiar with the available options for the 2.0L TDI engine.

Thank you, Ulf. At least one person takes me seriously. Otherwise, I would start to think that I'm not quite all there .

What I've noticed in the forum is that the somewhat newer engines are still considered "too unknown." However, I believe that as a professional, one could derive a diagnosis based on various findings.
The problems I repeatedly mention have been occurring roughly since someone messed with the timing belt.
Unfortunately, I am repeatedly told that the timing belt or its settings are correct, or that the engine simply won't start.

Here's a summary of the symptoms that can be listed:
-Increased consumption: 1.5-2 liters.
- Performance below 2000 rpm is very poor.
- Boost pressure below 2000 rpm: below target.
- Boost pressure above 3000 rpm: above target.
- Failed the ASU (driving aptitude test) twice. Despite passing the practical test, the K-value (a measure of driving risk) is 20-30 times higher.
- Engine noise changes under load. Brighter sound, the knocking sounds somewhat like chirping.
- Vibration and shaking when starting, with the steering wheel and mirrors vibrating briefly.

Since the timing belt was replaced (approximately 100,000 km ago), the following parts have been changed:
air filters, diesel filters, engine oil, coolant, brake fluid.
AGR-Ventil,Magnetventilblock,LMM,Kupplung und Ausrücklager, Drucksensor, Temp.geber G62 u. G83, Thermostat.
The hoses are all in good condition; I've visually inspected them multiple times. No abnormalities were found.
Only when the load is removed does a hissing sound come from the vacuum chamber of the charger. But that should be normal...

I'm constantly being drawn towards the need to replace the timing belt.
The BKD engine has two camshafts: one for the intake valves and one for the exhaust valves.
Could a synchronization issue between the two be causing the problems?
Or is it electronically monitored, so that an error would be recorded?

What about the measured values? Do they need to be plausible even when the engine is off and the ignition is on, or only when the engine is running?
Z.b ist bei Motor aus, der LD-Soll Wert 180mg/hub. Der Förderbeginn bei 13 v. Off-topic.
I don't have those values memorized, but if it's relevant, I can look them up again.

Regards,
Serdar.

Quote:

What about the readings? Do they also need to be plausible when the engine is off, ignition on, or only when the engine is running? Z.b ist bei Motor aus, der LD-Soll Wert 180mg/hub. Der Förderbeginn bei 13 v. OT

That's normal. When the engine is not running, the turbocharger cannot regulate boost pressure. The feedback (FB) cannot be measured. The target values for these parameters are then just placeholders. You have to program some kind of value to represent "not available."

However, when the engine is idling, you can check the LD sensor to some extent for plausibility; it should display the same value as the ambient pressure sensor.

It could be due to a slightly misaligned timing belt. However, to determine this definitively, you'll need to find a "very, very good" workshop or obtain the repair manual for that specific vehicle.

Okay, so the values don't matter.
LD-Ist and atmospheric pressure are always the same. This area is within acceptable limits.
However, the actual LD value is below the target LD value.

For example, the values at idle:
Atmospheric pressure: 958 mg. LD-Ist: 958 mg.
Target LD: 1023mg, Actual LD: 958mg.


As mentioned, this difference between the target and actual values persists even above 2000 rpm.
According to my understanding, a well-functioning system should always reach its target value.
Or am I wrong?

Greetings.

Quote:

As mentioned, this difference between the target value and the actual value persists even above 2000 rpm. According to my understanding, a well-functioning system should always reach its target value. Or am I wrong?

The performance of the load dump (LD) protection should only be evaluated under full load, and a pressure difference of less than 100 mbar is acceptable in that case.

Malte1408 wrote:

The LD regulation should only be evaluated under full load, and then a regulation difference of less than 100 mBar is acceptable.

. . . except for dynamic processes during initial adjustment, such as the overshoot when applying full throttle, which can, even in properly functioning systems, exceed the target by ~0.2 - 0.3 bar for about 1 second.

serdarg wrote:

... I'm constantly being drawn towards the need to replace the timing belt. ...

What else could it be!

This was already mentioned earlier by Ulf.
All the other values you mentioned are largely normal (as far as one can tell without complete logs).

Yes, and the 2.0 16V engine exhibits the same symptoms as the 1.9 engine.
However, it's worth noting that a phase difference between the camshafts in a 16V engine can also cause some problems. I've never personally encountered such a situation.

Quote:

What I've noticed in the forum is that the somewhat newer engines are still considered "too unknown."

Perhaps you're just not looking hard enough. First, the BKD is an old model, and second, the same applies to consumption as has already been written here many times.

Okay. The timing belt replacement is definitely due in the next few weeks anyway. Since I can rule out everything else, all I can do now is wait.
"Nevertheless, thank you all for taking the time and effort."
Greetings.

Small update:
While I haven't replaced the timing belt yet, I have fixed another problem that was causing a significant portion of the increased fuel consumption.

And specifically, the pipe was corroded, which is known to be the best type of construction , of course.
The connecting pipe between the exhaust manifold and the EGR cooler was leaking in one spot, or was almost completely corroded through.
"Four VW workshops couldn't figure it out, and the independent workshop I usually go to even thought I was crazy. They would have thought I was imagining things... everything would be fine with the car..."

It happened by chance. I had a friend who was a VW mechanic working at the gas station, and he was on call that day, so I asked him to take a look.
After a long period of hesitation and checking, he initially didn't want to recognize anything.
And right where he was inspecting the injection molding area, I gave it a quick burst of gas... and sure enough, a thick cloud of exhaust came out from behind the engine block.

That explains why my engine compartment always got so dirty... Once, a VW master mechanic told me, in response to my question, "It's probably pollen dust..."
"He couldn't explain to me how pollen could accumulate in my engine compartment, whether it was during the winter or the summer."

Okay. Anyway, I'm not crazy, and I was right to suspect that something was wrong.
The fuel consumption has decreased from 9.5-11 liters to 7-8.5 liters, and the performance at lower engine speeds has also improved.
Sure, the EGR valve is there for a reason. In areas where exhaust gases are recirculated, the proportion of fresh air is adjusted accordingly.
And if the exhaust gases can no longer escape properly, then the cylinders will not be filled correctly either, and so on.
It's a shame that in this "VW mecca" of sensors and value monitoring, none of this was considered. After all, there are many possibilities in this area that can lead to performance loss and increased fuel consumption.
I don't know exactly where the heating/air conditioning system draws air from for the interior, but if it's located in the engine compartment, then these kinds of malfunctions can also pose a health risk (which I was exposed to for over a year...).

Greetings.
Serdar.

PS: The only indication of the problem that appeared electronically was the actuator test in the engine control module (ECM). When the EGR valve was activated during the test, the amount [of something, likely exhaust gas] decreased, and the engine would occasionally stall.

Another update.
The thing about the consumption was nonsense. Before I lead anyone else astray.
By replacing the connecting pipe, the fuel consumption has changed only minimally. At most, it has decreased by half a liter.

What has actually improved is the performance (or power delivery) in the lower RPM range. Previously, there was a rumbling and shaky feeling when driving up to around 2000 RPM.

The issue is resolved, and now it's time to replace the timing belt. During the replacement, I'll also check to make sure everything was properly connected, and if so, that the camshaft gears are correctly aligned with the camshafts themselves.
It's possible that according to the timing marks on the gears, everything appears to be aligned with Top Dead Center (TDC), but the gears themselves might be misaligned with the camshafts.

I came up with the theory myself, but I'm not sure if it's technically correct.
I believe there is a deviation between the intake and exhaust camshafts, causing the fuel to be injected too early or too late. I don't know which configuration leads to increased fuel consumption .
But I'll figure that out too...