Solved: 1Z Power Loss Due to Overboost Pressure

Hello,

Since last night, I've been experiencing a loss of power with my 1Z engine in my Passat 35i.

The following happens:
It behaves normally until the boost pressure rises, not to the usual level of approximately 1.1 bar as indicated, but instead increases to around 1.3-1.5 bar. After that, it drops very quickly and then rapidly increases again in the first four gears.
On the fifth gear, the same phenomenon occurs: the boost pressure rises again to 1.3 bar, then drops and remains low until you release the accelerator and press it down again.

I suspect it's probably due to a solenoid valve or something similar that limits or controls the boost pressure.

Boost pressure control valve / solenoid valve / N75.
028 906 283 F - €35.76

I hope you can help me with the diagnosis.

Either the turbocharger boost pressure control valve (N75) or its control circuit is faulty, or the small high-pressure hoses connecting the boost pressure line to the N75 and the turbo's pressure sensor are damaged.

For testing purposes, try bridging these hoses at the N75 valve (but use these two, not the ones from the air filter housing). The LD (boost pressure) should then settle just above 0.6 bar, and definitely not exceed 1 bar. If that's the case, then it's likely the N75 valve; otherwise, it's probably the hoses.

Regards,
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It refers to a sudden and strong gust of wind.

and do it soon, otherwise you'll end up like I did two years ago.

The solenoid valve is defective (~35€), but by the time I found it (I followed the same procedure as described by Guste above - thanks to the forum ), I had already replaced several "burst" charge pressure hoses for a total of 70-80€.
And actually, I can still be glad that not more broke .

heating fossil

It was the valve.

So, the problem is solved.

Thank you for the feedback!