Mehrverbrauch nach Zahnriemenwechsel 1.9TDI AVF | Posts 24+

My fuel consumption remains high... however, today in traffic, I noticed that when accelerating moderately at around 1800-2000 RPM, the engine doesn't run smoothly, and I would say that for a petrol engine, the mixture is too rich. This hasn't happened before. When accelerating with 3/4 or full throttle, it doesn't. I tried this while stationary: I slowly pressed the accelerator pedal further and further. At first, the RPM increased slowly. At around 1800-1900, the RPM stalled, even though I continued to press the pedal. Suddenly, it increased to around 2300-2400, even though I had only given it very little gas. This allows me to nicely regulate the engine speed again, but it's difficult to maintain the engine speed in a specific range, for example, between 2100 and 2500 RPM, because it either drops or immediately increases further. This wasn't the case before either. I don't think it's directly related to the timing belt, but it definitely started after the replacement. But it would fit well in my description that I need significantly more in urban traffic, and on the highway, where the RPM is higher, this problem is less or not noticeable at all.

Okay, to summarize:

- The engine requires too much diesel, especially in urban traffic.
- Timing is perfect and the synchronous angles are at 0° (without needing to be adjusted afterwards!)
- Performance drop during moderate acceleration at approximately 1800-2000 RPM, but he pulls strongly at full throttle.
- No excessive Russian development visible
- Current consumption in BC at moderate acceleration in 1st gear: 40.8 liters, in 2nd gear: 27-35 liters... Definitely wasn't like that before.
- LMM was traded in for a used one - behaves exactly the same
- AGR (for testing purposes) deactivated using a plate and screw in the hose

Which log files should I create so that I can assist you further? It would really be great if my Audi was like it used to be

Since it seems that the problems started after the change, something must have happened here as well. If the timing is correct, everything should be okay at the front. "You've probably already noticed that the bearings with guide rollers are quite stiff, I guess."

What exactly did you work on during the ZR change and the other tasks? DiFi? Something seems to be broken, possibly now somewhere, and it might be leaking and drawing in air?
Intake air hose checked? All connections are sealed, no rags, gloves or anything inside? When closing the AGR valve, did anything fall into it and enter the intake tract? Excessive buildup that has partially detached? A damaged sensor cable, incorrectly routed, loose connectors...?


Since this car is so sensitive, it must have simply registered something differently. Since you've been working on it, it must be related to that. Check all the steps, lines, and cables that you moved.

matthiasTDI96 wrote:

Since it seems that the problems started after the change, something must have happened here as well. If the timing is correct, everything should be okay at the front. Stubborn bearings in ball bearings, you've probably noticed by now, I guess.

Yes, I'm assuming that too. The question is just what I did . I can still turn the timing belt again, all pulleys including the water pump, by hand. No discernible difference from before.

matthiasTDI96 wrote:

What exactly did you work on during the ZR change and the other tasks? DiFi? Something seems to be broken, possibly now somewhere, and it might be leaking and drawing in air? Intake air hose checked? All connections are sealed, no rags, gloves or anything inside? When closing the AGR valve, did anything fall into it and enter the intake tract? Excessive buildup that has partially detached? A damaged sensor cable, incorrectly routed, loose connectors...?

I had the diesel filter replaced just 30,000 km ago. Otherwise, I had a service performed, including new air filter, complete replacement of climate O-rings, new dryer, and replacement of the valve cover gasket. I have checked for any leaks in the pipes/hoses/cables, and I have not found any. Even when accelerating to full speed next to a wall, I do not hear any hissing or other signs of a loss of boost pressure, which would lead me to believe that the problem is not related to the AGR system. However, I will still have the system pressure tested. The test phase with the AGR system is already taking some time, and I do not believe that it is the cause of the problem. I have also checked the sensor cables, and since I'm not seeing any value [or a plausible value] in the VCDS [system] for the corresponding sensor, [that suggests...]

matthiasTDI96 wrote:

Since this car is so sensitive, it must have simply registered something differently. Since you've been working on it, it must be related to that. Check all steps, lines, and cables that you moved.

I did that when I checked the ZR again (by pulling the locking bar forward etc...)
I worked with the repair manual "So wirds gemacht", which was a red book. I have trained as a commercial vehicle mechatronic technician, so it's not as if I'm completely clueless.
The only thing that is demonstrably different is the synchronization angle. But it can't be the case that if you correctly adjust an angle that was within tolerance before the change, the car will then run poorly.

That's why I want to continue using VCDS, as I've already done a lot of mechanical work myself. So far, what I've been looking at seems good, for example, the boost pressure is being achieved and the air mass is slightly above the target (without AGR).

Best regards, Tobias

Hello,

........just a silly thought:
Have you ever tried to recreate the 3° synchronization angles from before and then performed a power consumption measurement?
After all the things you've already tried and checked, there's no need to expend a lot of effort to get to the bottom of the "mystery."


As I said, just a thought

Greetings, Mpire

The idea isn't that stupid
However, I have tried this already, and it did not result in any significant changes...

Are you sure it's not just due to the cooler weather?
I find it fascinating that the oil temperature is higher.
You can only achieve this if you burn hotter or cool less.
I need to review this carefully again.
Best regards, Frank

Please check your temperature sensors.
Pot, Thermometer, Ohmmeter and a table showing the resistance to measure at which temperature.

Best regards, Frank

F B wrote:

Are you sure it's not just due to the cooler weather? I find it fascinating that the oil temperature is higher. You can only achieve this if you burn hotter or cool less. I need to review this carefully again. Best regards, Frank

Yes, that's me, I've owned my car for 3.5 years and it has 110,000 km
I checked the temperature sensors with VCDS, and even if they are a few degrees off, that shouldn't make such a big difference. G62 is only about 2 years old.

I hope I'll be able to create the log file for the boost pressure next week. I checked it again briefly today, and the boost pressure is always present and adjusts to the target value, even at low speeds, and is within the driver's desired torque range below the redline. However, when accelerating at full throttle without any engine speed, it briefly reaches the redline, which is normal. I hope I'll get around to creating the log file soon, even though I don't really expect much from it...

Greetings

Unfortunately, I still haven't managed to get the log file for the boost pressure. However, I gained a new insight today. I disconnected the mass airflow sensor, and the car ran significantly worse afterward. So, still running smoothly, but the power was almost non-existent below 2400 rpm, like without turbo, and then the power gradually returned. I connected the LMM while the engine was running, and immediately the full power was restored.

I replaced the LMM about 2 or maybe even 3 years ago. Back then, I didn't have a VCDS to read anything, but I remember that disconnecting the LMM barely made any difference.

Could this be related to my problem? And can someone explain why it's losing so much power without an LMM? Both my experience and what I read online indicate that removing the LMM (likely referring to an emissions control device) results in the engine running smoother or even better.

Warm greetings

Tobias

Quote:

Both my experience and what I read online indicate that the engine runs smoother or even better when the LMM is disconnected...

In case of very old toilets, possibly...

Well, it's certainly not the youngest anymore, but I don't understand why it makes such a difference now, and not before... so, I can't understand my car at all since the ZR change

Hello everyone

Troubleshooting continues
Consumption is still too high, especially under light load. In addition, the engine consistently stutters at approximately 1900 1/min. Sometimes more, sometimes less. And with full throttle, it practically never runs out of power, except in 6th gear. Okay.
Yesterday, I checked the intake system for leaks and found no leaks. I also removed the AGR valve, which was almost perfectly clean. Therefore, there were no deposits or anything like that. I replaced the mass airflow sensor with a diode, but it didn't make any difference except that the check engine light came on after about 30km, and the engine's RPM dropped below 2400 1/min because the MSG detected an implausible air mass.

Furthermore, I attempted to create a log file today. Can anyone work with this? I uploaded the .csv file as it was saved by VCDS. I feel that the time intervals between the individual measurement points are quite high. Can this be adjusted somewhere?

The first measurement was at full throttle (maximum speed) in third gear, the second log file was created with moderate acceleration (as I would accelerate with a cold engine), and the fuel consumption in the KI was 40.8 liters.

I am grateful for all the feedback

Best regards, Tobias

Hello,

The engine should not jerk or stall at 1900 rpm, even under full load.
Check the coolant temperature in the Engine Control Unit (ECU) and compare it with the temperature in the KI-ECU.

Quick login: see KPower instructions.

Best regards, Rainer

tobias_ wrote:

Around 1800-1900, the engine speed has stalled. Suddenly, it has risen to around 2300-2400, even though I only gave it very little gas...

Hi Tobias,

The VTG jumps precisely in the area around 1800 RPM. For me, your description sounds like a slight loss of boost pressure, but it's clearly not so significant that the boost pressure sensor detects it.
When the VTG is fully engaged, there is a jump to 2300 RPM. This likely describes your problem exactly. Therefore, don't look for the "spritzufuhr" but for the air supply.
Possibly, during the ZR (Coolant) exchange, an LD (likely Low-Pressure) hose was damaged, or it is not properly seated in its mounting.

...or the LLK was caused by increased pressure.

Hello everyone

Temperature sensor is io, values match, 90.9°C after 1 hour on the highway.

I was also considering the possibility of a slight loss in boost pressure, but since the engine has practically no boost pressure (i.e., when not under load), it shouldn't really make a difference, right? As I mentioned, I checked the intake system for leaks, and simply replacing the intake hoses on a whim is also not exactly cheap

Regarding the VTG control, which controls the flaps fully even at low engine speed because there is little exhaust gas flow, I don't understand what you mean by "jumping" or "starting to approach," or are you saying that he begins "re-adjusting" at that moment?

I will create a new log file with a finer granularity as soon as I have time, perhaps you will then be able to identify something.

See you later, and best regards.

Tobias