randall977
19-02-2009, 02:46 PM
05 A4 Cab 1.8T 163bhp (57K). I thought I had sorted out this boost problem when I replaced the boost pressure sensor but it seems to have crept back! Basically you accelerate and it pulses the power or lurches. It is accompanied by a shhhhh noise (a steady noise - maybe a cylinder not firing??? - a vacuum leak???) when it does it but not when the acceleration is fine (which it is sometimes).
Here's what I know;
The turbo wastegate operates when a footpump is connected to the actuator control line.
The turbo does not smoke and the play in the spline is within tollerance - spins freely.
The DV is new.
The boost pressure sensor is new.
The intercooler does not have a hole in it.
No other fault codes, fuel economy is good.
Here is my list of possible faults;
The N75 valve.
A small hole in the vacuum system.
Ignition coil.
Any advice greatly appreciated. I am on the verge of buying a VAG COM but it feels like I'm throwing money at a problem which could all end up with me having to fit a new turbo - but there's no evidence that the turbo is the problem...!!!
Here's what I know;
The turbo wastegate operates when a footpump is connected to the actuator control line.
The turbo does not smoke and the play in the spline is within tollerance - spins freely.
The DV is new.
The boost pressure sensor is new.
The intercooler does not have a hole in it.
No other fault codes, fuel economy is good.
Here is my list of possible faults;
The N75 valve.
A small hole in the vacuum system.
Ignition coil.
Any advice greatly appreciated. I am on the verge of buying a VAG COM but it feels like I'm throwing money at a problem which could all end up with me having to fit a new turbo - but there's no evidence that the turbo is the problem...!!!