JunpoweR

iTrader: (1)

Yesterday I replaced My stock old and dry vacuum hoses with brand new BMW ones..First I unplugged the stock Pressure sensor(N370)harness to get at the vacuum line going to that..redid everything and now the stock pressure gauge stays at 0 all the time..Even on throttle with a load the car reads 0 ..I have a full RB exhaust installed with no FCD and it used to cut before i installed the new vacuum lines but the stock gauge would still show me the boost and go over and under 0 ..whenever i throttled too much overboosted the stock fuel cut would kick in whenever i throttled too much and had a little too much boost..nothing serious..Now after installing the new vacuum lines it always stays at 0?!and the boost dosent cut even when i step on the gass all the way....Like a magical FDC but I didnt install it yet since its comming from japan?>!@@!!now im afraid it wont matter if i install my FCD since the stock pressure sensor isnt working it dosent CUT fuel anymore ..would that be my problem??@#!!whats wrong with it??i checked everything and reinstalled new vacuum lines again and i still have the same problem..Did the stock pressure sensor short circit while i unplugged it and plugged it back in??are they that sensitive?!@# WTH..STUCK AT ZERO!! 0 could it be the stock pressure sensor blew while i replaced my lines??!!someone help me out..

YearsOfDecay

DO NOT BOOST YOU CAR until you get this fixed....

The fact that the stock gauge doesn't read and the ECU isn't cutting fuel is telling me that the pressure sensor isn't seeing any boost, THEREFORE, the ecu isn't seeing any boost and ISN"T ADDING FUEL... you will BLOW IT if you run too much boost without the ecu correcting for fuel...

Check your line to the pressure sensor...

to check your pressure sensor, turn the ignition on, but don't start the car.. now apply a few pounds of air pressure to the vaccume hose attached to the pressure sensor.. the gauge should move even if the car isn't on.

I can also tell you how to check the gauge using a voltmeter and a computer power supply if you can't get the wiring correct.


Check your connector as well..

BUT is suspect a connection proble with a vaccume line

HAILERS

Either you did not reconnect the wire harness plug to the boost/pressure sensor, or .....the vac hose is not connected to a nipple that shows vac/boost pressure. One or the other.

When the key is off, the gauge should read well below zero. Turn the key to ON and the gauge needle should go to zero. That would prove the electrical connector is indeed on the boost/pressure sensor. Sooooooo....it must be that the vac line is off??? OR not going to the proper nipple. One or the other.

SureShot

And - after you get it working - did you get the orifice pill from the old hose & put it in the new one?

JunpoweR

iTrader: (1)

orifice pill?? whats that??
and i just went and bought more vacuum hoses silicone ones so i will be changing it ,, AGAIN!!
hopefult time it works..

So Orifica pill?? whats that again?

Digi7ech

iTrader: (1)

Like I've asked multiple times. What type of restrictor pill is it?

What are the downsides of running without one?

I've got a TII convserion so I don't have this pill.

JunpoweR

iTrader: (1)

ok i also got my Knight sports fuel boost cut controller i will try installing them together..

SureShot

The orifice pill (restrictor) is a <1/8" dia x 1/4" long plastic plug with pin sized hole through it.
It installs in the hose near the pressure sensor.
It damps pressure spikes so you don't get unnecessary fuel cuts.

Digi7ech

iTrader: (1)

OK that makes sense. I gues I can pick something like that up at checker.

JunpoweR

iTrader: (1)

ok i installed the knight sports fuel cut defender and still same problem while engine running i took off the hose going to the pressure sensor and blew on it hhad someone in the car tell me it went up and when i sucked it went below 0 so its not my pressure sensor..!!
Well i redid the hoses again and throttled and checked for any vaccum or pressure comming from the hoses going to the tube right above the turbo.. and i didnt feel anything?? what could this be??
should i just remove the vacuum lines completely to the stock location and tap it into the other intake outlet that is plugged?? will this work??

J-Rat

iTrader: (2)

Sounds like you tapped into the wrong vac port. Where is the source for your press sensor coming from?

HAILERS

Idle the engine. Pull the vac hoses off the intake manifold until you find one that creates a vac leak. Then connect your pressure sensor to that nipple on the intake manifold.

You have a series five.....I have a series four, so I can't describe where you should find the right nipple.

TurboII2NV

hmmm I am readin this and have a question
my gauge boost gauge hasnt been working for the longest time now, and there is nothing wrong though
car boosts fine and runs ok
and it stopped working when I took off my air pump(maybe that could have something to do with it)
and I can even take off the vacuum line off the boost sensor and nothing will happen

J-Rat

iTrader: (2)

ARe you sure its the gauge or the sensor? Sometimes the gauge goes bad, and the sensor doesnt.

TurboII2NV

well my gauge is ok I guess cuz it does move a little
but not too much
not as much as it used too before I took off my air pump

JunpoweR

iTrader: (1)

it dosent show the vaccum dosent go under or over 0 at all just stays there after i start the engine..
what could be wrong..
When i disconnect the hose going to the pressure sensor and blow on it the gauge goes up and when i suck it goes down..??!!
so it should work..
When i reattach it it dosent work..
When im driving the blow off works fine so there must be pressure or vaccum when i am driving but the gauge dosent work still..only when i suck or blow into the pressure sensor myself it works..how could the blow off still work and the gauge not work unless i physicaly send pressure to it myself and how could the blow off still work if its not working??!!

TurboII2NV

I am not sure but my blow off valve works perfectly fine as well and the gauge is not reading
and the car is boosting fine and right at the proper boost

J-Rat

iTrader: (2)

Junpowr,

Where are you sourcing your vacuum for the boost gauge?

JunpoweR

iTrader: (1)

everything is stock i just replaced everything the way it was before i touched anything
ok u know where the hose comes off the engine to the T section that seperates the lines to the blow off and the pressure sensor..
thats all i did replace these lines and it stopped working..

J-Rat

iTrader: (2)

But when you take that hose off the "T" and blow on it (or suck) it gives a reading on the dash?

TurboII2NV

why is it a big deal if the gauge is not working? and everything else is ok?

Wankels-Revenge

A few threads earlier he said he tested the gauge and its working. The problem obviously isn't the gauge then.

I'm also pretty interested to see what the problem here is cuz i'll be changing my vac lines soon as well.

JunpoweR

iTrader: (1)

OK
if the stock computer dosen't sense boost then i believe it won;t compensate for fuel and air mixture under boost and the timing probably wont retars itself either which could cause ur engine to blow really fast!!
So Im sure this is bad if the stock gauge isnt working i should hit fuel cut no matter what without a FCD..
so the stock fuel cut dosent work anymore and i don't think thats good..Also can i tap the blow off lines and the pressure sensor to where the blow off is going into in the diagram??I don;t know why this picture is diffrent but..On my stock S5 90 turbo II the line comes off the ACV and T's off to the pressure sensor and the blow off valve..
In this diagram only the pressure sensor is connected to the ACV and the Blow off IMO from the diagram is taped into the little pipe comming out the manifold that is usually blocked off with a rubber stopper..Could i just run both the blow off and the pressure sensor off of this and would it be okay to just leave the stock ACV open.. leave it there??I will remove my Smog pump also so i dont think I will have a ACV anymore..
Where does everyone hook up the stock pressure sensor to and the blow off?? after the ACV is blocked off and removed??can i just hook it up this way temporaily till i remove my smog pump??
Replaced the hoses again to no avail!!

Here is the steps i took once again..


First i changed the stock vaccum lines from the pressure sensor to the T to the ACV and to the stock blow off valve..

before i did this i was hitting stock fuel cut due to my full racing beat exhaust.I know not good so I would not step on the throttle over half boost readings on the gauge since i didnt have a FCD..
ok I change the lines turn my car on and go for a drive and it stays at 0!!!
when i let off the throttle 0 , on throttle it reads 0..!!
but i noticed My fuel wasnt cutting out without the FCD..
when it should since i was overboosting..So I have aq magical fuel cut defender which is not good since the stock computer dosent sense the boost and wont adjust the fuel for it..So Im really stuck!!
I take off the vaccum line going to the pressure sensor at the t ..
I blow and suck on it and have a friend glue his eyes on the boost gauge..!!
He said it went up half way!! and when i sucked it went down also..So i hooked it back up while the car was running and took it for a drive...Still no boost readings on the stock gauge.
My stock blow off still works fine so why would it be doing this ??
Would my ACV (air controll valve) be broken??
the gauge worked fine till i changed the vaccum lines!
so yea if there was ) vaccum why would the blow off valve work then ??im stumped..

here is the diagram and it dosent have the pressure sensor t ed off with the ACV or blow off.
If you look closely the ACV goes to the pressure sensor and the blow off goes to a little port the is usually covered of with a rubber stopper if ur car's pressure sensor is t with the ACV and the blow off like mines is right now..I wonder if i hook it up as in this diagram would it solve my problem..Well see tomorrow since it's too dark and im too lazy today..



if this dosent cure my problem im really stuck!

J-Rat

iTrader: (2)

Cliff notes?

J/K.

Try a source other then the ACV. My ACV is removed, and my system works fine.

HAILERS

It's possible you have it coming off the wrong nipple on the ACV. It should be coming off the nipple off the nipple that sticks straight out towards the right fender.

Only one nipple on the ACV is pulling a vacuum. Its that one I just described. The one at the bottom GETS pressure from a *vac*line. The one in the middle more or less...puts out PRESSURE. Only the one at the top has a vacuum. The one on top that sticks straight up GETS a vacuum FROM the vac line that attaches to it.

Like I said, just idle the engine. Take that hose off that sticks straight out at you. Feel the vacuum on the nipple??? You should. Thats the only nipple that pulls vacuum. The others do not (talking only about the ACV).