Vacuum leak?

[MM BOOST]

Alright, here lately I've noticed my car has been seeing vacuum numbers that aren't normal. When I first turn the car on, it idles at 17 vacuum. When I am driving the car, and im not getting it any throttle and the car is just coasting, its at 19-20. When I stop the car and its idling again, sometimes it goes to 15-16 and just sits there. Do I have a vacuum leak? Its really bugging me. Another thing I've noticed recently is that my car only spikes to 15 psi and then tapers off to about 11 psi when I am going WOT. This can't be normal. This car drives me insane, I can never seem to figure out the problem/source of the problem when boost numbers are not hitting like they should. My mods are as follows:

-hks ssqv
-turbo xs stealthback
-racing beat exhaust
-injen cai
-medieval turbo inlet
-denso iridium one-step colder plugs
-s.u. boost tubes
-aem prosport mechanical boost gauge

I really wished I could figure out what the hell is wrong with my car. Absolutely blows my mind why I am not hitting boost like I should. I've torn the car apart and put back together 3 times trying to find a leak somewhere and never do. Re did all the clamps, re did the inlet install and everything. nothing seems to change. Could my fuel pump need upgrading?? I was wanting to do the CDFP internals soon and I guess it would make sense that the internals aren't efficient enough to hold the boost. Also, I am going to be getting a FMIC soon, so I know that will increase efficiency as well.

 

[Kain]

It could very well be your boost gauge is off. Prosports are notorious for inaccurate readings. Do you have a Dashhawk/Dashdaq to read boost off of the OBD-II, or can borrow one?

Since you have a mechanical boost gauge, it's entirely possible you have a kink in the vac line.

 

[AutoEuphoria]

Check to make sure the line going to the BPV isn't cut. I know that I was having that issue until I physically took the BPV apart and put it back together so the vacuum line fitting was down further. Other than that, check your fitting to the boost gauge and make sure there's no leak there (as Kain mentioned), and check all your couplers/vacuum lines that you normally have to remove or replace to install the stuff you added. Vacuum leaks can be extremely frustrating to trace, so I wish you the best of luck! I would also suggest trying to find someone locally with a DashHawk (or get one yourself) so that you can see what the actual vacuum is and compare it to what your gauge is reading.

 

[MM BOOST]

Wow, I didn't even think of the boost line having a kink in it. I guarantee the way I have it ran it is kinked. I ran the line down the fender and in through the door ( i did it right after I got the car before i joined this forum and I couldn't find a way through the firewall) so it goes under the weather stripping of the door, I bet that its kinked/crushed in a spot. Where is the best place to run the vacuum line in at?

I do not have a dashawk, yet, however I plan on getting one soon! I really need to get one I am assuming from all the talk about them.

 

[Kain]

Where is the best place to run the vacuum line in at?

You have two places, one in the driver footwell, the other behind the glovebox. The glovebox firewall grommet is bigger, but you'd have to run your line across the engine bay. The longer the line, the more chances of rips/kinks. The driver footwell grommet is smaller and less accessible. Get down low and trace the hood release cable. You'll see the grommet behind some sound deadening. Pull the grommet out, snake a metal hanger through the hole and it'll end up near the left upper strut mount.

Because that firewall access is tight, I would wrap your line in a loom to protect it against kinking or tears.

 

[MM BOOST]

Wow, thanks man. I am going to go outside soon and re-do my vac line. I really think its kinked. As is, its run behind the battery box, then down inside the fender, then through the edge of the door. So when I close the door, I know it kinks the line. You guys have been a bunch of help, this makes me feel like a tool. And I've tried everything, except this.

 

[MM BOOST]

Oh and btw, would the line being kinked make the vac readings read like I posted up top and would it make the boost appear to be tapering off?? Is the kink causing the line to collapse or something? If someone could explain this, that would be great.

 

[Kain]

Hope that helps. Next time I'm your way down I-81, you can buy me a beer. Or give me your Racing Beat CBE. Whichever.

 

[Kain]

Oh and btw, would the line being kinked make the vac readings read like I posted up top and would it make the boost appear to be tapering off?? Is the kink causing the line to collapse or something? If someone could explain this, that would be great.

Yes, any leak or kink will make your gauge read less vacuum. Pretty much at idle (and depending on your altitude and whether your A/C compressor is on), you should see roughly -20 InHg. Anything less than that, you have a leak/kink.

 

[MM BOOST]

Hope that helps. Next time I'm your way down I-81, you can buy me a beer. Or give me your Racing Beat CBE. Whichever.

you can come buy it so I can buy a greddy ti-c or an HKS if you would like! (thumb)

 

[Kain]

Figh dorrah?

 

[UHATEIT]

The Dashhawk will be a great benefit. I have a cheapy guage cluster setup and when I bought a DH I noticed how far off my gauges were.

My gauge reads like 21-22 vac at idle, but the DH shows 19-20, and It's about 2 vac less on normal driving on the gauge than when I look at the DH, as in I drive and its at 10vac while the gauge is reading 12

 

[MM BOOST]

well i went out and redid the vacuum hose and its still doing the same thing. Vacuum will only go to about 16-17 tops. I also noted wrong, its an autometer sport-comp mechanical boost gauge. Is my gauge faulty or something? Its driving me insane. Car felt strong today when I was out driving it, but the damn gauge is off. I am thinking of just scraping the boost gauge and getting a msd dashawk and mounting it in place of the boost gauge. the dashawk shows boost and all that stuff just like a boost gauge, correct?

 

[MM BOOST]

Figh dorrah?

if by figh dorrah you mean buy a hks catback, then drive down and swap exhaust with me, then you got it pal! (nana)

 

[UHATEIT]

the DH is much better and the digital readout is much more precise running through the OBD2 plug. As I was mentioning, the results and readouds on the digital screen of the DH were night and day compared to the one off the the needle point gauge which was off in many spots

 

[MM BOOST]

so i figure'd out my problems. My hot side clamp on the intercooler was stripped and would not tighten. So from the increased air flow, heat and pressure, that hose would flex and my boost would leak. Also, I found out that the vacuum line where it goes into the back of the gauge (the gold fitting), the fitting itself broke. There was a little gold piece that went on the end of the line that held it into the fitting. Well that piece broke away from the fitting, so you can hear a faint hissing when the stereo is turned off. This would explain why my vacuum is not reading like it should.

 

[UHATEIT]

s***. all kinds of people having leaks from the boost tube clamps. i might tape a screwdriver to mine to be on the safe side

 

[MM BOOST]

now i gotta figure how the **** to fix this damn boost gauge. You can hear it hissing constantly. UGH Anyone have any ideas?

 

[AutoEuphoria]

Pull it out and redo the whole vacuum line. There's really no way to fix that plastic tubing if it's gotten crimped.

 

[MM BOOST]

see thats the thing. Its the fitting that goes onto the end of the vacuum tubing that screws into back of the boost gauge so it can read vac/boost. It broke. I wonder if I could get something like that at advanced?