Kirk

I did a little searching under the hood and found out that I had a leak on the hose going from the intake manifold to the by-pass valve control solenoid.

Here is the long story:

The by-pass valve control solenoid has three vac lines: (a) from vac res. (b) from intake manifold, (c) to by-pass valve.

Anyone care to comment on how the by-pass valve control solenoid works?

I'm wondering what happens when the hose from the intake manifold to the solenoid is disconnected or loose. The way I see it, the solenoid stays open because its got more vac pressure than manifold pressure and thus, it puts vacuum on the line going to the by-pass valve itself and this keeps the by-pass valve open.

This system is different than the 1.8T motor without the control solenoid. Without the solenoid, if the vac line on the intake manifold comes loose, the by-pass valve stays closed for ever and causes turbo damage over time.

I was getting a boost control: negative deviation code and started to look for leaks on the pressure side of the turbo going to the intake. I swapped out my 710N (TT) by-pass valve with a new 710N and that didn't solve the problem so I kept looking. Found out that a hose clamp on the vac line from the intake manifold was loose and the hose was leaking air however slight. I've since corrected the loose clamp and checked the intake air track for leaks. Cleared the code and reset everything with the ECU. I'm hoping I've found my problem. The car seems to be back to normal now.

Kirk

DirtySoap

So what would charge pressure positive deviation be? I had that code pulled earlier this week

Kirk

... but I would guess its like an overboost error. The pressure sensor is seeing too much boost. This could be due to a number of things. Check your boost pressure regulation.

Kirk