: Is my Gauge wrong???



magna-v
03-21-11, 03:28 AM
I have a 2004 v maggied w/magnaflow x-pipe and catback, i bought a plx DM-100 gauge from a buddy of mine with the boost and afr sensor modules. this setup was on his Grand National and worked just fine and read accurate boost #'s as well as afr.

I installed everything tonight except for the wideband because i dont have any extra o2 bungs at the moment but i did a couple WOT runs on the freeway and im not sure if i connected to the right line on the maggie. at 5800 rpm WOT it read 9.6#'s of boost!!! seems high to me. Im maybe a couple hundred feet above sea level in seattle on the freeway but dam!! as far as i know it has a recent maggie due to the carbon shaft and 2.8 pulley and exhaust. i bought the car with the mods and not much background info because it was from a dealer. the only thing i got was a box of stock parts in the trunk.

The line i tee'd into was the line that goes into the magnavolt about 6 inches away from the maggie itself. the gauge was very accurate on my buddys GN so im not really not sure what to think, Help me out here:crying2:

CancerJCC
03-21-11, 11:46 AM
Is there an electronic sender or does the vacuum line run all the way to the gauge?

magna-v
03-21-11, 02:57 PM
its an electric sender

Twitch
03-21-11, 06:33 PM
Could be a ground offset problem. Easy to check the calibration though. Key on, engine off it should read zero.

magna-v
03-21-11, 07:40 PM
twitch, just checked like you said, it does read zero but .2 flashes flashes once in a while but for the most part it stays at zero

CancerJCC
03-21-11, 08:07 PM
its an electric sender

The reason I ask is what Tony said. Grounding offset problems. Do you have anyway to change the gauge settings? Like a program that came with the gauge? If not all you can do is ensure a really good ground and roll with the reading it gives you. I personally installed a 2 bar MAP sensor so I could see what boost I was getting in HP Tuners over a WOT run.

Heres some light reading on grounding offsets: http://www.innovatemotorsports.com/forums/showthread.php?t=3410 They are terrible in the V btw...

CancerJCC
03-21-11, 08:12 PM
BTW Here is a thread that can give you some comparison as to what boost level you might be seeing. Remember boost is just a measure of restriction so there isn't an exact number but some of the guys will be close to yours.

http://www.ls1gto.com/forums/showthread.php?t=142006

One guy with just more cubes for example:


I'll just add a couple.

Stock LS2 engine with just catback magnaflow, stock 2.8 blower pulley= 6.5 psi.

Stock LS2 engine with Magnaflow catback, Kooks 1 3/4 LTs w/catted midpipes, 2.7 pulley=6psi.

ctsv154
03-21-11, 09:40 PM
Look at the harmonic balancer and see if it's stock. If it's a huge silver Innovators West, that would explain the extra boost. If it's a stock black one, somethings up.

Twitch
03-22-11, 08:24 AM
Also, if your sure you have a 2.8 in front check the rear pulleys. Is one smaller?

CancerJCC
03-22-11, 02:11 PM
Look at the harmonic balancer and see if it's stock. If it's a huge silver Innovators West, that would explain the extra boost. If it's a stock black one, somethings up.


Also, if your sure you have a 2.8 in front check the rear pulleys. Is one smaller?

Good points. BTW If its huge and silver like Bobby suggested then you need to get it off there asap and I'll trade you for the black one you need. :)