Error 17553

hello

The following error occurred today.

Error code: 17553.
Air mass flow meter G70: Short circuit to positive voltage, intermittent.

Possible causes:
Short circuit to positive _ G70 defective.
Line interruption or short circuit after the positive terminal.

Possible consequences:
reduced performance.
Black smoke.


I've been testing the Pierburg mass airflow sensor in my van. Today, while accelerating, I noticed a drop in power between 3200 and 3800 RPM, almost like the engine is being limited. After that, I got the error message mentioned above.

If you release the accelerator and then press it again, the same thing happens: the LMM (lambda measuring module) values reach a certain level and then decrease.

The Excel tab is attached, and the corresponding values are highlighted in red. For your information, the AGR system has been offline for testing purposes for the past week.

I checked this using a VAG scope, and it looks like the MAF sensor is being briefly deactivated.

My question is: how can it be that the error only occurs briefly and isn't constantly present, if the error message indicates an 'intermittent' short circuit? Or is something else possible? Could it be that the control unit can't handle the relatively high values from the mass airflow sensor (MAF)? How could this potential defect be fixed without replacing the MAF sensor? Is it really a short circuit?
I haven't tested yet to see if the error occurs with the Bosch device.

'Thank you.'

Sure.

The Pierburg sensor (for the characteristic curve stored in the MSTG) is reporting too much air.

If the BOSCH sensor only outputs a maximum of 4.5 volts on the measurement line, while the Pierburg outputs 4.9 volts, it might appear to the MSTG system as a short circuit.

And then it does what it's supposed to do. It ignores the measured value and sets 550 mg/H as a replacement value (I've never heard of a "persistence value" before).

If it measures a value within the expected range, it re-selects that value.

Therefore, the "intermittent" (sometimes like this, sometimes like that) nature.

either: connect AGR, insert diode, and it's done .
or the original LMM (i.e., BOSCH).

But it's interesting that the Peirburg apparently doesn't fit 100%.

m;

Hi,

It shouldn't be related to the EGR system, as the problem only occurs under full load. The measured values for the engine idle (with the EGR system deactivated) are good.

I can't think of any other workaround. It might be possible to limit the operating voltage of the mass airflow sensor using a 1N4001 diode, but this could also lead to unpredictable behavior if the electronics inside the mass airflow sensor cannot handle the reduced voltage.

Best regards, Rainer.

Persistence value

It referred to the model 1275.



Connect to AGR, insert diode,

agr is closed.
'Using a diode would be a solution. Then, you would only need to check the voltage value and then select the appropriate diode. This way, you could always set the LMM value to, for example, 1100 instead of 1275.'


Aber interessant, dass der Peirburg wohl doch nicht 100% passt.

I also think so.

I have another idea: we could modify the characteristic curve stored in the engine control unit (ECU). This would have the same effect as a diode.

@rainer

I'm referring to your EGR because "diode in" and "EGR open" is funny.

Then the thing is constantly running with the EGR valve fully open, and it sounds really strange (I did that for my initial LED tests). Strangely, this doesn't trigger any error codes on the diagnostic system.


I just wanted to point out that "Diode -> Agr zu" applies, but "Agr zu" doesn't necessarily force a "Diode".

m;

Let's think about it again.

'The error only occurs with increasing engine speed. The MAF sensor value remains at 1275, which suggests that 1275 might be the maximum value the engine control unit (ECU) can display. However, the actual signal from the MAF sensor is increasing until the error occurs. It would be interesting to know the actual value that the MAF sensor is providing.'

I also spoke with the company that sells the LMM today, and they were just as surprised as everyone else about the high value it's bringing. So far, it's the only one that's delivering these results. I'm getting another one shipped next week, so we'll see what that one does.

Peter.

Hi Peter,

What is the diameter of the air mass meter connection, 70mm?
Then it should be clear why: a 2.5-liter engine with tuning (i.e., increased boost pressure) simply sucks in a lot more air compared to the standard 1.9-liter engines.
The corresponding 4-cylinder PD-TDIs that operate with higher boost pressures likely have an 80mm connection to the air filter housing (I only have one piece of evidence here, so I'm hesitant to generalize).

Best regards, Rainer.

@rainer

The connection has a diameter of approximately 70 mm, that's correct.

If I were to adopt your idea, then the new LLM, which we'll see when it's released, wouldn't work either, assuming the current one is functioning correctly.

If we assume that the 80 mm measurement is correct, it would also be possible to install a different air intake and other pipes for the turbo, specifically those with an 80 mm diameter.
If I assume the continuity equation, V = A1 * c1 = A2 * c2, then this would mean that the flow velocity in the 80 mm pipe would be lower, which implies that the mass flow rate per unit of time is lower, and the LMM (likely referring to a specific measurement or value) would be lower.
Another advantage would also be the de-throttling of the intake system, especially if you also modify the air intake opening.

I hope I'm thinking correctly; please correct me if I'm wrong.

peter





Function of hot-wire air mass flow sensor:

An electrically heated sensor element protrudes into the airflow. The temperature of the sensor element is always kept constant. The airflow removes heat from the sensor element. The larger the volume of airflow, the more energy must be used to maintain the constant temperature of the sensor element.