1.8t Lingo

[Ian_83]

I'm new to all this VAG stuff, so a few quick questions about the names of some parts and what they do.

N75 valve - From what I can tell, its just a boost controller? It connects to the actuator to open/close the wastegate? If I went with an aftermarket controller, I could just bypass this?

N249 Valve - This can open/close the DV to purge boost at any point? But my car being a 96 won't have one?

DV - From what I can tell this means diverter valve? Is this what I would know from the jap scene and a dump valve? Purging boost on closed throttle? I assume recircing it back into the system due to the fact the car is a MAF, not a MAP.

Any clarifications would be hugely helpful,

Thanks,

Ian.

 

[aragorn]

N75 is the ECU's electronic boost controller. IMO theres little point bypassing it. You cant run any more boost than the map is programmed for, as if you exceed it the ECU will drop into limp mode. If you want more boost, you need to alter the ECU's programming (ie a remap) and you need the correct fuelling and ignition timing to match the additional boost anyway.

a '96 wont have a N249, as far as i can tell its only fitted to cars with electronic throttle. On a '96 the DV is simply plumbed into the inlet and works normally.

DV has multiple definitions, Diverter Valve being the most common, it also just means dump valve. As you've guessed the standard valve is a recirculating dump valve, and the engines dont like atmospheric valves due to the MAF sensor. Atmospheric dump valves are often referred to as "blow off valves", which to me is yank terminology but meh.

 

[Ian_83]

Thanks for that. My main reason to bypass the N75 is so I can monitor boost controller, plus then have a hi/low setting. Not to meantion the pimpness of an HKS EVC

 

[hades-]

if you run a EBC hks gizzmo etc
the oem N75 will be bypassed anyway but keep it pluged in to stop the light comeing on