: Questions about boost gauge
09-18-2005, 05:28 AM
I just purchased an Auto Meter Pro-comp Ultralite boost gauge 2 5/8 size.
At idle I sit at 10 vacuum, my Vortech is rated at 8lbs boost but I only go up to 5 on the gauge at max RPM. After driving for a minute I sit at almost 20 vacuum idle and at 10 vacuum while driving. Shouldnt I be showing some boost while driving, at least 1lb or 2lbs at 2 1/2 grand. Even at 3 grand im not even at zero.
This is my first FI'd car as well as the boost gauge so id like to know if there was a kink in my vacuum line or something.
09-18-2005, 09:14 AM
Where is the reference vaccum line running to? Mine runs off the manifold.
At idle I'm between 14-18 inches of vaccum.
09-18-2005, 02:11 PM
Mine is running one of the nipples off the back of my intake manifold.
09-18-2005, 07:26 PM
Was the car tuned with the Vortec on it before the cam's and cam gears?? Cam gears set differently when FI, on a NA motor you want overlap to help push the exhaust out of the cylinder. On FI its just the opposite, you dont want your boost bleeding out of the exhaust.
Maybe its the cams, since the Vortec is driven off the crankand will only produce X amount of boost at a given rpm and your cam is bigger than stock its possible you getting more into the cylinders which would make it look like the pressure is low.
Just a couple of idea's to think about, hope it helps[thumb]
09-18-2005, 09:27 PM
Thanks, I will set back to 0,0.. Now say i still am getting some overlap at 0,0 on both cams, what would fix that? retard the exhaust? Right now they are at:
Intake: 2 Retarded
Exhaust: 2 Advanced
09-18-2005, 10:11 PM
I still new to adjusting the gears, but on my turbo motor Tom set them at ...
2* retard on exhaust
12* advance on intake
EDIT:^^^^^^ I think thats where they are set.
He would be a better source of info on gears than me.
09-18-2005, 10:29 PM
wow, ill try that.
09-19-2005, 12:58 PM
wow, that ran like shit at that setting! I went back to 0,0 but still only have roughly 6lbs boost at 7 grand..?
09-19-2005, 01:43 PM
It may not be making all the boost it was advertised as. There are MANY factors that affect boost on a car. It might only be making 6 lbs. If you have access to another buddies boost gauge, plug his in and see what you get. I have seen more than one boost gauge be off as well.
09-19-2005, 06:06 PM
With my Vortech kit I'm at 8lbs at 6500rms.
Which vacuum line specifically are you hooked into? You should be connected to the fuel pressure regulator vacuum line. You'll only make boost when you're on the gas at wide open throttle.
At idle I run 20 in/hg, cruising its going to depend on how much you're on the throttle so you can't really go by that.
Maybe it's just me but I wouldn't think cam gears are going to affect your boost. A vac/boost gauge detects positive or negative pressure in the intake manifold. I can't think of a reason the cam gears will affect boost. Vacuum would make sense because it's how much air the engine is sucking in. Boost is positive pressure, which is being created by the compressor. It's how much air is being forced in.
My money is you have a vacuum leak somewhere. Check all your lines, including the egr lines.
09-19-2005, 07:05 PM
i run around 17-20 at idle. Do you have a pic of where you tapped in for your signal?
09-19-2005, 10:38 PM
Looking down at the intake manifold from the top over the valve cover there are 4 nipples. My boost gauge is connected to the bottom right nipple:
o o <----- Boost Gauge
I would not know where to begin to look for a vacuum leak, would that affect my boost level? Perhaps a boost leak is present, where would you search for that?
09-20-2005, 12:40 AM
a vacuum leak would also be a boost leak. You do have a T in your boost gauge right, you didn't just take one off and leave it hanging?
Trace yor vacuum line and tell us where the one you tapped into goes. For example mine goes intake manifold -> T -> fuel pressure regulator. The other branch of the T goes to the boost gauge. As far as looking for a boost leak, you can make a tester by hooking up some piping but I haven't done it yet, I've just seen people do it.
Also out of curiousity why are you running 2 step colder plugs? I run the vortech with nitrous and still only run motorcraft 1 step colder.
09-21-2005, 05:25 AM
103,000 miles is why.