A4 AHH: No Power, Then Over-Voltage

Hi,

My friend has a 1999 Audi A4 with the AHH engine.
The car had no power (it could only start at 3000 RPM) and was emitting thick black smoke.
Then he replaced the mass airflow sensor (MAF) and also the turbocharger.
Result is the same! The LDA valve replaces (the original).
There was always a lack of air mass, and consequently, a lack of LD (likely referring to a specific parameter or measurement).
Then he sealed the AGR valve with a strip of BOPP material, which eliminated the smoking and restored the engine's performance. However, on the first drive, the LD (boost pressure) went up to 2500 mbar (according to VAGCOM), and then 'boost limit exceeded' appeared.

Could a completely blocked EGR valve now be the cause of the 'too high' pressure?
The AGR valve itself is clean and functioning properly. Tomorrow, the lock will be removed, and the system will be tested with a new solenoid valve for the AGR.

Hi, hi... actually, a blocked EGR valve shouldn't be the cause of the problem. We all drive with the EGR valve closed without any issues. In my case, with the AFN engine, it was the turbocharger (VTG) where the adjustment mechanism wasn't working correctly.

The AHH has 90 horsepower, right? With the turbocharger, the linkage might not be properly adjusted. Therefore, it's worth checking and possibly adjusting it slightly to reduce the boost pressure.

Do you happen to know if the AHH block is the same as a 1Z/AHU/AFN?

Best regards,

Gunnar.

The AHH has a VTG loader. If the VTG is extremely clogged, the jammed VTG can now cause the standard error .

mullemaus wrote:

The AHH has a VTG loader. If the VTG is extremely clogged, the jammed VTG can then cause the standard error

.
Okay.
As a convenient troubleshooting attempt, I would run the actuator diagnosis a few times with the engine idling (if the charger intervention occurs before the cutoff ), to work the VTG a bit.

If that's not possible, run the default setting "MWB 11" on the LL for 5 minutes or longer. However, this setting has a slower clock speed than the actuator diagnosis, so it will take longer to perform the same number of valve travel movements.

Hi,

Are the vacuum connections for the turbocharger/AGR valve swapped?

Best regards, Rainer.

Rainer K. wrote:

Are the vacuum connections on the turbocharger/EGR valve swapped?

Hi Rainer,

"That would be consistent with a stuck-open EGR valve and excessive soot buildup when accelerating."

However, the AGR (Abgasrückführung valve) closes when you give it a lot of gas -> resulting in no vacuum.
Then, in my opinion, the loader should deliver rather too little than too much LD (load data).