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View Full Version : +-+-Boost leak fixed, now its boosting 25psi?!?!+-+-



SeanF
03-24-2007, 01:40 PM
So, i found my boost leak, and i temporarily fixed it...

but now the problem is, on a standard GIAC k04 ecu, im boosting 25psi...

if i play with the throttle and keep it under 20psi it feels good, but once it gets to 20-25psi it starts gettin rough, what seems like misfires...

the first place i think to check is the n75 valve. what else could it be now?

oh and what i thought was an exhaust leak, wasnt. yippe...

Ewok_Fetus
03-24-2007, 01:42 PM
When is the last time you changed your plugs and gapped them? Could be blowing out your plugs... Just a thought.

SeanF
03-24-2007, 01:51 PM
they were changed not too long ago, brk6e's gapped at .028...

my fuel trims are closer to ok now...

they went from:
-1idle; -11part

to now:
-3% idle; -5.5% part

NyteEscape
03-24-2007, 02:57 PM
you might need to get a step colder to nrk7e's. the 6 is basically for stock people who want copper. anything chipped and above should go with 7's.

mike-2ptzero
03-24-2007, 03:34 PM
have you checked the vac line going from the N75 to the wastegate, sounds like the wastegate isn't opening enough to control the boost so it just spools up all it wants.

bOOOOstedAudi
03-24-2007, 04:04 PM
have you checked the vac line going from the N75 to the wastegate, sounds like the wastegate isn't opening enough to control the boost so it just spools up all it wants.

this same think happened to me. I thought I fixed my boost leak and my car was just boosting really high when really i fixed the leak and blew off that hose mikes talking about. well i thought this for 2 week until one day a motorcycle and freeway came in my path, to make a long story short i was really boosting about 30-35 psi, only showing 25-27 and blew out my piston rings, seal and a head gasket. cylinder #2 was done and the rest work compressing to well anyway.

CLICK HERE IF YOU DON'T REMEMBER (http://audizine.com/forum/showthread.php?t=119057&highlight=BOOOOSTEDAUDI+DEAD)

SeanF
03-24-2007, 07:26 PM
i was thinking it had to be something to do with the wastegate and or n75...

i guess ill tear into it tomorrow :-\

bOOOOstedAudi
03-24-2007, 07:29 PM
i was thinking it had to be something to do with the wastegate and or n75...

i guess ill tear into it tomorrow :-\



wtf are you :-\ing about. better safe then sorry $2500 later

bOOOOstedAudi
03-24-2007, 07:30 PM
although this is a cool pic
http://i146.photobucket.com/albums/r256/boooostedaudi/100_1079.jpg
http://i146.photobucket.com/albums/r256/boooostedaudi/100_1078.jpg

SeanF
03-24-2007, 08:32 PM
yea, i took it real easy on the way home tonight...

by the way, is that an ECS underdrive pully or just the lightweight? how do you like?

Poopie
03-24-2007, 11:30 PM
nice sean, i told ya you would figure out it. You were saying you were gonna give up and sell it lol. I told you it was something simple.

SeanF
03-25-2007, 06:42 AM
now i have to figure out why its doing what its doing now... im gonna bust into it in about 20 minutes...

SeanF
03-25-2007, 08:41 AM
the hoses to the n75 *seem* to be fine, but i was going to replace them anyways, however, they are different sizes on each end...

is there an easy way to test the n75? i blew through the hose from the turbo, and it just blew straight out the hose going to the wastegate... no resistance...

that seems like it would be a sign of a failing n75... but i dont know...

also, what pressure spring is in a k04? i think im going to bypass the n75 until i can get the right hoses and test the n75...

Rosati
03-25-2007, 09:20 AM
Bypass the n75 and tap into the IM and itll run at 5psi , slow as hell, but safe.

mike-2ptzero
03-25-2007, 09:45 AM
Bypass the n75 and tap into the IM and itll run at 5psi , slow as hell, but safe.

Actually you just run the pressure hose which feeds the N75 valve from the turbo compressor housing or IC pipe, dont really want to tap into the intake manifold since a vacuum isn't needed for running the wastegate and there will be a pressure drop at the intake manifold vs the turbo housing.

Rosati
03-25-2007, 09:50 AM
Oh i see, well thats what i did and the car was stable

It'd be ideal to have a drop at the housing vs the IM , of course. but this was easier at the time

mike-2ptzero
03-25-2007, 09:50 AM
the hoses to the n75 *seem* to be fine, but i was going to replace them anyways, however, they are different sizes on each end...

is there an easy way to test the n75? i blew through the hose from the turbo, and it just blew straight out the hose going to the wastegate... no resistance...

that seems like it would be a sign of a failing n75... but i dont know...

also, what pressure spring is in a k04? i think im going to bypass the n75 until i can get the right hoses and test the n75...

The N75 valve is controlled by the ecu, it should be in an "open" state when not being controlled by the ecu. If you can blow thru it and it stayed this way while running you wouldn't make more then 5psi. Hitting too much boost means there isn't enough pressure being sent from the N75 valve to the wastegate actuator. Any chance you have the N75 installed incorrectly? Maybe you have the "WG" and "intake" sides switched. IIRC the longest nipple should go to the intake tube but you might want to double check that.

mike-2ptzero
03-25-2007, 09:54 AM
Oh i see, well thats what i did and the car was stable

It'd be ideal to have a drop at the housing vs the IM , of course. but this was easier at the time

well you really dont want to run more then 1.5 ft(18 inch) of hose to control the wastegate. Longer hose would increase boost spikes because of the added volume in the longer hose, this is the same thing when going with a larger size(ID) hose.

Rosati
03-25-2007, 09:55 AM
the longest N75 tube goes into the TIP (the left side , the right side of the "cross" goes to the actual wastegate

SeanF
03-25-2007, 10:09 AM
it should have been correct, i had never messed with it before...

im contemplating an EBC or a new n75... we'll see...

so with the n75 connected and the engine running, i should not be able to blow through it, but with it disconnected, i should?

mike-2ptzero
03-25-2007, 10:19 AM
Well you could always try using a MBC in parallel with the N75 valve if a new N75 doesn't help, using it this way will allow you to decrease boost spikes and decrease max boost.

SeanF
03-25-2007, 10:21 AM
why not use a mbc instead of the n75? like on big turbo setups?

except i dont want the shitty one that comes with the elim kits, because everyone replaces those anyways...

anyone have an n75 i could borrow to see if that fixes my problem?

mike-2ptzero
03-25-2007, 10:35 AM
why not use a mbc instead of the n75? like on big turbo setups?

except i dont want the shitty one that comes with the elim kits, because everyone replaces those anyways...

anyone have an n75 i could borrow to see if that fixes my problem?



Because a MBC used alone increases boost spikes during high load. The MBC also doesn't work all that great with a K03/K04 because it just sets a max boost pressure which that size turbo cant hold throughout the rpm range like a BT can.

SeanF
03-25-2007, 03:00 PM
i see, so an EBC also wouldnt do the trick?

i guess i need to buy an n75... cheapest place for a stock one?

SeanF
03-25-2007, 04:47 PM
ordered an n75 and mbc from ECS... we'll see how it goes...

maxspeed
03-25-2007, 05:00 PM
no need for an n75 at all straight mbc isnt terrible like everyone says it is, mines really smooth..

SeanF
03-25-2007, 05:30 PM
im going to use a MBC in parallel with the n75 at first.

i really wanted to use a greddy profec b spec 2. which i may still do...