Volkswagen Passat Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
46 Posts
Discussion Starter #1
Well I installed my n75J during the week, and noticed a little difference with it :)
The car definitely pulls a lot better in second and third, and the boost is much more even. Running Vag-Com on block 115, I could see straight away that it was holding at least 2-3 psi over the factory fitted valve - the car is stock for the moment.

Strangely enough, my car was fitted with a factory installed n75C, which I though should have been an F valve...

Anyway, after getting used to the n75, I then checked out my Dawes Device (MBC) http://www.dawesdevices.com and installed it today. I unscrewed it first, then screwed it back together, using Rustys' handy tip that one turn is roughly equal to 2 psi. I was looking for .8 bar (12 psi) , so I gave it 5.5 turns, and popped it in. I know its something you are supposed to adjust from factory once you have it installed, but its such a pain to get at, I decided that this would be an interesting experiment if nothing else!

The install I followed was:

1: remove air inlet pipe and the piece of the air intake screwed onto the front grill. Two screws are all you need to remove this part.
2: unclamped and removed the fuel pressure regulator
3: removed the turbo nipple connector line from the n75 (the one opposite the solenoid i.e if you look at an n75, its shaped kind of like a cross. The solenoid and the inlet opposite are the ones in question here, rather than the two pieces at right angles to the solenoid. Remove the clamp (using a pincers, think takes a few seconds if you have the original factory clamps) and a few twists if you have jubilee clips.
4: attached the straight end of the dawes to the inlet hose, using a jubilee clip
5: attached the right angle on the other end of the dawes using about 1.5 inches of fuel line, and clamped in place with to more jubilee clips. This is a difficult piece, as the working area is so cramped.
6: put all the other bits back on and started the car.
7: made loud happy sounds when nothing blew up.

So I took the car for its first run, with my trusty Vag Com attached, and after a few miles, pulled over and crunched some numbers in excel. Boost held quite stunningly well at exactly .8 bar, and no spiking whatsoever. I've put about 50 miles up at this point, and it’s staying steady. Interestingly, the 5.5 twists seem to have set it at pretty much the level that I wanted, as 0.8 bar seems to be the limit of the fuelling programming on a stock ECU.

I do however have two questions:
1: I can now hear a bit of a whine (which I presume is the turbo). Is this normal when chipped or running an MBC?
and
2: Is fuel hose ok to use in this line? The walls are 3.5mm thick, so they look sturdy enough. Will they be able to take the heat though?

Hope this is some help.
T.
 

·
Registered
Joined
·
1,512 Posts
Most aftermarket chip will spike around 1.2 to 1.3 bar and settle around 1.1/1.2 bar when N75-J valve is used and it would still run little bit at the rich side. The sound of turbo whine is normal.

I would think the fuel hose will be fine, but if it worries you, then replace them with silicone vacuum hose and wrap around with heat sheilding material.

BTW, the stock N75 valve on most passats is C version.
 

·
Registered
Joined
·
46 Posts
Discussion Starter #5
well time for an update.

After a few more miles, I did detect slight "pause" sometimes at full throttle i.e a tenth of a second where there was a "flat spot" in the car's accleration.

After synching this with my boost logs, it was obvious that this was happening at full boost. So, guessing that this was the fact that the injectors were maxed out, I took apart everythign again, and closed the Dawes down a half turn. This has fixed the problem completely, and now all I have is a car which is significantly snappier, and far more drivable!

Thanks again to everyone for their information and feedback on this!

Best Regards,

T.
 
1 - 5 of 5 Posts
Top