Zu geringe Versorgungsspannung am N75 | Posts 16+

Connect an analog measuring device in parallel with the connected device. N75.
When the ignition is turned on and the engine is running, only a minimal voltage should be measurable.
After starting, the voltage should rise to approximately 12-13 volts.


'When the ignition is on and the engine is off, I have approximately 0.15 volts there. When the engine is running, it's only 10.5 volts, but I think that's not a problem.'

I'm disconnecting the control unit, and I've already been to the workshop to report the issue.

They are checking it, and I should be able to come back next week!

Really annoying!

Regards,

Manuel.

Manuel Thomas wrote:

When the ignition is on and the engine is off, I have approximately 0.15 volts there. When the engine is running, it's only 10.5 volts, but I think that's not a problem.

Hi Manuel,

It looks like you might have been measuring between the voltage supply and ground instead of in parallel with the valve (i.e., at its two

Quote:

terminals) - but it doesn't matter, the measured voltage range of 0.15 to 10.5V is okay.

I am disabling the control unit
I also - as I said, on the hardware:evil: side.
If your tuner, for example, only increased the target boost pressure without, for example, adjusting the external pressure limiting map, then there's a problem in the software .

However, I had taken parallel measurements. I exposed a section of the wire and removed a small piece of the insulation!

I measured the voltage from the power supply to the wiring leading to the control unit. But only when idling, and for a short time!

I'm still ruling out the chip for now, because I've never had problems with the 15mm turbocharger, and the 17mm one didn't have any software issues either, for a while! Except for the 0.15 bar higher boost pressure compared to the 15mm one! But that's not the problem! It goes into limp mode whenever it wants! Sometimes running in 'limp mode,' sometimes at full throttle, sometimes at a quarter throttle, and always with varying boost pressures!

Now, I'm going to investigate the 'G70 short circuit to ground' issue. If the wiring is also okay, I'll just go ahead and replace the G70.

You can still benefit from the new exchange program, even if your Pierburg mass airflow sensor is still working!

Thank you for your help. If you have any more tips, please share them!

Regards,

Manuel.

Manuel Thomas wrote:

However, I had taken parallel measurements. I exposed a section of the wire, and removed a small piece of the insulation!

Hi Manuel,

I had a 180° error in the interpretation of your measurement results .

Quote:

When the ignition is on and the engine is off, I have approximately 0.15 volts there. When the engine is running, it's only 10.5 volts, but I think that's not a problem.

Of course: Motor stopped -> valve de-energized = minimum voltage.
Idle speed -> VTG at maximum pressure = high voltage at the valve.

(Alzheimer is already starting to creep around the corner ).

Quote:

It just goes into emergency mode whenever it wants! Sometimes in "limp mode", sometimes at full throttle, sometimes with only 1/4 throttle, and always with different boost pressures!

Emergency mode in slide operation, meaning when there should be absolutely no boost pressure?
Extremely puzzling... My immediate thought would be sporadic mechanical issues (e.g., a problem with the charging unit, VTG, or a solenoid valve).

But after my "stellar performance" with your measured voltages, I (at least today) don't put much faith in it myself anymore .

Okay, I've now replaced the LMM (likely referring to a mass airflow sensor), and I drove my car 260 km along the Sauerlandlinie (a scenic route in Germany). Besides the fact that my old mass airflow sensor was still providing excellent readings, you can definitely feel a huge difference.

A45 uphill: 215 km/h, previously the maximum was only 205 km/h! He accelerates beyond 180 km/h just as if there were only 130 km/h displayed.

And the emergency stop error has also disappeared. I'm continuing to monitor it, but since I've already checked everything else, it must be the mass airflow sensor!

Best regards and thanks to everyone who helped me!

Manuel.