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Discussion Starter · #1 ·
Hey guys i just installed a digital boost gauge in my MKIV, and my car was peaking at 9 psi. iv been told 8-9 is normal but everyone says something different. My car has FMIC, and crappy intake, was told the bigger IC could lower my psi, but crap idk.
my questions is what is normal vacuum reading? my boost gauge goes negative, but not sure where it should be when it does.

I ask because my car goes into limp mode when i down shift to try to really give it gas. It'll get to 9 when i slowly build it up. I figured if my car was not reading accurate vacuum then must be a leak. If not i screwed something up installing gauge. Very possible.

I t'd up my gauge hose between the fuel pressure regulator, and intake manifold like i read up on a few DIYs.

The way the FMIC is installed, the hoses all around the DV are installed weirdly (could be bad, could be fine idk never had a light come on or go into limp till now) , due to crappy installation, but the car has always seemed to run fine. Will post pics in morning!!

Please any help would be awesome.
 

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What year (or engine code) mkIV?
 

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Car should be getting 11lbs
 

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20 ingh or whatever negetive mother ****in 20 at warm idle
 

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Discussion Starter · #7 · (Edited)
Well my car wasn't in limp mode today which is frustrating, because it was yesterday and iv done nothing to fix it., I boosted up to 10psi today and it idls at -10, -8 when ac is turned on

I was told this is my problem, the green dots are part of DV hose, and the Red is part of what used to go into the original pipe for SMIC, it has been t'd to the DV hose.
My boost gauge is t'd to Fuel pressure regulator. other picture shows the same hoses, and how i was told it was supposed to look, red is some sensor to hard pipe, green is DV to idk manifold i think. and his blue is where his guage is td. as you can tell mine is way diffrent red dot hose is td to dv hose and not in pipe.

 

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My AWP peaks at 14PSI and drops with revs... So that means I'm tuned? (Input on the state of my tune... Whether it's, stock, stage 1, or whatever would be greatly appreciated.)

Also.. You should hold 18-20 vacuum at warm idle. and 21-22 on decel while still in gear.
 

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well seems as if my car blows.... cause its way less boost and less vacuum.
I'll explain the vacuum a bit more... It should run 14~15 if there is a load on the engine during idle. (AC, Moving the steering wheel, Brakes, Cold start, etc.) Once it's warm and idling with no draw on the motor, It should be a solid 17 at least.
 

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I know stock for AWP is 11.5 PSI. But the FMIC shouldn't effect the amount of vacuum you run. I would check for a boost leak. Because it sounds like you have a small one. Go ahead and tighten every single clamp you can. I would bet it's a cracked rubber hose though.
 

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the vac at idle should be around 20 & depending on the size of ur fmic and pipes u may lose a few psi on the boost side but u should roughly be boosting 10-12 psi without a tune , with a tune u will be between 18 and 25 on the ko3s turbo .

My idle in my 2004.5 GLI with AWP engine (usually stays between 19-21 on the vac side)
 

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Discussion Starter · #15 ·
Is the fact that the hose that is supposed to be in hard intercooler charge pipe, but T'd to DV (refer to picture i posted earlier) hose gonna cause problems?
my only option on that is to get new intercooler piping that has the air hose connections on it, but cant find one anywhere, or find local shop that can bend and weld one for me. (Not likly)

found my self a quite street and put my foot down and only got up to about 7 Psi, it still idles at -8 and -10 with no ac.
 

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Is the map sensor in the piping?
 

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Discussion Starter · #17 ·
Yes it is, i had it welded on the pipe. It was aluminum on aluminum. I need to find a hose nipple that's aluminum that'll weld on but can't find that. I think the hose is 1/4inch
 

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Yes it is, i had it welded on the pipe. It was aluminum on aluminum. I need to find a hose nipple that's aluminum that'll weld on but can't find that. I think the hose is 1/4inch
The sensor itself is welded? Pics?

If that sensor is bad and you have leaks, could be your problem.
 

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Discussion Starter · #19 ·
Sorry I ment, I had an adapter welded on that I got from 42 draft. And the sensor screws in like it would on stock SMIC.
 

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Gotcha. I'd double check the intercooler piping and go from there. How big is your fmic core?
 
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