ImQuattro®

How else, besides wastegate/N75 operation, does boost feedback affect the ECU? Can it be left disconnected? (Temporarily & plugged of course).

a4kquattro

the ecu's timing and fuel maps (partially) rely on it to run the motor correctly.

ImQuattro®

can anyone verify this? What does the ecu do w/ this info?

quattro.pilot

affected by how the ECU interprets and corrects for that pressure.

tpierce

just pull the hose and find out what happens.

ImQuattro®

But if the boost is then controlled by an higher rate spring, w/ the ECU pressure line disconnected doesn't the ECU still correctly compensate A/F mixture using the 02 sensor readings and adjust timing using knock sensor values, coolant temp, oil temp and MAF sensor input?
Seems to me, and I don't have ECU code here in front of me, but it seems to me that the only thing the ECU does w/ boost input is to know whether to modulate it up or down (or limit it) by activating the N75 valve.
The rest of the engine's performance is affected by other inputs.
The only way I can see it playing a role is if the ECU using it like a MAP sensor to detect engine load but the AAN's use a MAF sensor.

4Driver4

No boost for you.

UrS4boy

On the UrS4s, that hose comes loose at the moisture trap on the firewall and people complain about no boost, no power. Two minutes (okay, five, you need to cut off the old OE clamp) and the smallest gear clamp you have = 70 hp. Otherwise, the only boost you get is that from the wastegate spring, i.e. about 6 psi (gauge) (stock spring).

If you want to disable the boost for a 'valet' mode, disconnect the WGFV.

4Driver4

The hose comes off when the car is already running. If the hose pops off while driving, get ready for some serious pinging.

4Driver4

No.