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Boost issues

1264 Views 18 Replies 5 Participants Last post by  lookin4avw
Ok so let me introduce my current set up.... 2001 wolfy with giac x+ (usually boosts up to 20psi), 3" turboback exhaust, and the N75J valve. I've been hitting limp mode (~10psi) randomly. It even happens right after the ecu has been disconnected for a good length of time. Things i've done....
-Thoroughly checked for vacuum leaks
-replaced spark plugs
-replaced the maf
I had the N75J in series with a mbc, figuring the mbc might have a bad spring or something I removed it. Now it hits a 'super limp mode' and only boosts 4psi. Again this behavior is random. I've spent lots of time searching for solutions and haven't come up with anything. If you have any suggestions please give me a hand.
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Also there is no CEL associated with it....wierd....I will try and get my hands on some type of scan tool tomorrow just to check it anyways. Also you can rule out the J-valve being in backwards
........I'll try and come up with more specifics to help pin down possible issues here. Open to any suggestions...
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I just installed a k03s on my 01 jetta in place of the old k03s,
Now im hitting limp mode i think it could be from not running any hose clamps on some of the hoses least i hope, limp mode sucks I was getting the Code p0171 its from running lean, you could have a bad MAF or a loose seal around the pan cake pipe!
i didnt have a CEL while i was in limp mode at first eather I had a friend that had a scanner so i learnt a bit about it yesterday
my car is my anti depressant and it its not runnin to its best im like.... AHHH!!!
No diode mod
The pancake pipe has been thoroughly inspected because i've had problems with it in the past
I have a new maf so shouldn't be the problem
Re: (lookin4avw)

It might be possible that your N75 valve has gone bad...try swapping in the OEM one to see if it helps.
Also, do you have an Aftermarket DV? If not your stock DV might have a tear in it which can result in serious boost lost.
I have a forge diverter valve - yellow spring - fresh diaphram, a bad n75 is what i've been leaning towards. Unfortunately I broke the stock one so I'd have to buy a new one to find out if this is the problem. Extremely poor at the moment:\
oh yea car has 70k on it if that helps anything
looking for help ............... I know this is a kind of a shot in the dark topic but I'm trying to narrow it down. Also I know this is very similar to the 'my car is in limp mode what do I do now' threads but I figured someone might have a little insight with whats going on considering the relationship when the mbc was connected then disconnected......Anybody?
Re: (lookin4avw)

gots no idea...its really annoyin in limp mode with CEL way to not impress the ladys
haha im thinkin its gotta be a 02 sensor....
but theres 2 on exhaust one before cat and in the cat, how can you test a 02 sensor?
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use a multimeter to read voltage at each O2?? That would be my only guess. I'm not running a cat aswell so maybe that's giving me problems. This sucks!
Re: (lookin4avw)

you can find a stock n75 valve for some change in the classifieds, I screwed around with a j valve for a while and got tired of going into limp .... I went back to stock and have been enjoying limp free since I made the swap http://****************.com/smile/emthup.gif
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I'm thinking along the same lines as you ulua4me, to see if the n75 is the problem I removed it, clamped a screw in the intake connection and now have an mbc doing the work. The n75 is still electronically connected as I've heard it the ecu doesn't like it unplugged. Resetting the ecu now, got a 1.5 hour drive back to school this afternoon so I'll let anyone who's watching this tread no the outcome later this evening. Wish me luck!
Re: (lookin4avw)

So I've got about 100 miles on the car since switching the boost control set up and guess what??!!?!?!
Car runs great! No limp mode so far smoothest boost curve I've ever had in the car and an added bonus of no CEL anymore(longest its gone without popping up).
Only down side is that I'm beating on it all the time so I'm getting used to it; facter in heat soak due to factory IC and shes slllllllllllooooowwww

I know I'm probably jinxing myself my talking about how good the car's running but I hope this might help some of you guys out there wiwth the same problem.
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