anyway to tell if a n75 valve is good or not without a vagcom?
12-24-2007, 07:45 PM
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anyway to tell if a n75 valve is good or not without a vagcom?
i noticed when i step on it in 3rd the boost jumps to 16psi and climbs to 20psi or so at higher rpms. when before it would jump to 20psi and taper down. i tryed pressure testing and im pretty sure i hear leak somewhere on the spider hose, though its my first time doing it. and im starting to think it could be the n75 valve. i have all upgraded hoses so i dont think its a hose connection anybody have any ideas? I dont have a vag so yeah.... so i throw i new n75 valve in anyway? merry xmas by the way!
12-24-2007, 09:59 PM
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I have the exact same problem with the same symptoms.
I traced the boost leak to the brake booster valve which I epoxied the crap out of temporarily to seal the valve. I'm still getting about 3 lbs less at WOT unless I keep it floored then it will slowly climb to the usual boost. I haven't pressure tested it again but I'm starting to suspect the N75 valve too.
12-24-2007, 10:01 PM
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I'm in the same boat. Only getting ~8lbs of boost. Don't know if it's the N75 or a boost leak,
Going to pressure test after Xmas. Have a buddy with a N75 that's not as bad, so I may swap that to test and see if I get a different reading. Stage 3 at 8lbs isn't as much fun. 
12-24-2007, 10:21 PM
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Checked codes. Got one for my pass rear O2 which I have on the shelf and..
One for running too lean... which seems odd.
???
From what I've read, doesn't seem either of those would call for limp mode... but I've been wrong before. Had the O2 for a while now, since it's sensor 2, I wasn't in a hurry to swap it.
???
From what I've read, doesn't seem either of those would call for limp mode... but I've been wrong before. Had the O2 for a while now, since it's sensor 2, I wasn't in a hurry to swap it.
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12-24-2007, 10:34 PM
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too lean will limp mode you immediately. That's a concern
Rear O2's will not, they are emissions only.
That "too lean" code is something you need to pay very close attention to. There's a reason that the N75 put you in limp mode for that, and I'd much rather be too rich than too lean.
That "too lean" code is something you need to pay very close attention to. There's a reason that the N75 put you in limp mode for that, and I'd much rather be too rich than too lean.