Mehrverbrauch nach Zahnriemenwechsel 1.9TDI AVF | Posts 32+

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

Quote:

The boost pressure at full throttle is approximately 2600 mbar absolute.

A bit much for a series engine - would even be quite high even with tuning.
Could it be that the atmospheric pressure hose to the N75 was pinched during the ZR (Zylinderkopf) replacement, and that's why the VTG (Ventil- und Steuergerät) remains closed longer than it should?

Unnecessarily high boost pressure = increased back pressure also causes increased fuel consumption, as the efficiency of the turbine + turbocharger is not equal to 1.

My Audi has been chipped by the previous owner. The modification with the hoses would theoretically be possible, but I haven't seen anything on the hoses, nor have I seen anything in my VCDS. If that were the case, then when I accelerate hard and then maintain a constant speed, I would have a too high boost pressure. The charging pressure also corresponds well to the target value and decreases sufficiently quickly. (Tested on the highway)

Best regards, Tobias

Have you refilled the tank or changed the fuel?
(That would be too simple)
I would now unscrew each hose on both ends and test for a free passage with compressed air.
Take a look inside each hole to see if anything is stuck inside or out.
Check each hose for leaks.
Over time, however, everything has already been proposed.
If you've already done all of this, there's essentially only one thing left (according to my limited knowledge): a sensor that provides incorrect data.
Does your engine have a MAP sensor, or is the vacuum in the intake manifold measured?
Not the fact that there is dirt sitting there that distorts the values.
I replaced the mapsensor at AXP a while ago, and it resulted in more than 20 percent less fuel consumption, and no error codes were displayed in VCDS.
Of course, it cannot be directly compared to a diesel engine.

Best regards

I always fill up with diesel
Seriously, I usually fill up at the same gas station chain. And the consumption was determined over a period of time that was too long, so it couldn't have had an influence . Similarly, temperature fluctuations. I've also thought about the sensor. I hope that I will be able to create new log files over the weekend, as I think that will be the most helpful.

Best regards, Tobias

If the state is 30, but the sensor transmits 40, then 40 is credible for you and the control unit.
I replaced my Mapsensor on suspicion because there was nothing else left.
Expanded and compared directly with the New one.
Even the resistance values varied, unfortunately I didn't write down the exact values.
The exchange yielded an average of 2 liters.
With a friend who had the same engine, the fuel consumption decreased from (city driving) 13 liters to 9 liters for the same activity, without requiring me to use VCDS to make any observations.

So, when the engine is cold, disconnect the connector, measure, and compare with the specified value at this temperature.


Best regards

I've also thought about something like that, and I ordered a new LD sensor last weekend
But it hasn't arrived yet, maybe it will be helpful, but the connection with the ZR change would be an unbelievable coincidence.

I was just trying to create new log files that are more informative. However, I couldn't find this "Turbo" button, even though I consulted the manual. The screenshots are attached. Could it be that my engine control unit is too old for this? VCDS is currently up-to-date.

Best regards,

Tobias

Quick Logging: EDC15 (old engine control unit) could be the cause.