Ok, I have a minor problem that's bugging me.

I got my new S/C from Gm put in and after all the trouble trying to get computer flashed I finally got that resolved. I installed a couple of gauges, one of which being a boost gauge. I T'd off the FPR line as you will see in pictures like everyone suggested.

The gauge with show vacuum correctly. At idle, it reads about 23 inHg. When I first start the car and bump the throttle it will go past zero into a little of positive boost which I know, I really won't see boost until I am in gear and put the engine under load.
By the time I get to the highway and go to WOT the gauge will stop dead at zero and won't go past.

Now, if I pull over and shut the vehicle off for a few minutes, then I can start it up and take off right away the gauge will climb to about 6 PSI. After about 15 or 20 seconds it will go back down to zero and will never get above zero.
It still reads vacuum just fine .. if I push in the clutch while driving the reading will drop to about 23 inHg and while cruising it can be around 15 inHg.

I also tried two different gauges both being brand new with no difference.

Should I be worried that it does not show boost?

Have any of you ever experienced this?

Do I have a leak somewhere maybe? Or installed something wrong.


I am using 1/8" hard plastic tubing for the vac line to the gauge and used zip ties to ensure the line was sealed at the connections.

Tee off FPR



Had to splice line because wasn't long enough

hmm not quite sure, but i know all those zip ties aren't necessary, maybe one is pinching something, hence the erratic readings

id just make sure nothing is blocking the line

Thanks for the quick reply .. I removed all the zip ties to see if it would make a difference .. I guess I went overboard with those .. anyway it's still a very tight fit on all the connections .. I was kind of worried that maybe somethign was wrong with the supercharger as I am new to dealing with boost on any vehicle and I guess with a supercharger as long as its turning .. it's working .. right? also could PCM programming affect this as well .. maybe its all in my head but it jsut seems that when I pull over and turn off the vehicle for aminuite then start it up and right away the boost gauge reads 5 to 6PSI when I go .. the car seems to accelerate a little quicker than when it's reading zero BUT that is probably just in my head because I am seeing 5psi at first as opposed to seeing zero psi the other times ..

I think I will take it to a dyno and check it out to see what numbers its putting down

In mine I made friend the following: take the hole for the clock him but near the small tube that provides the supercharger there it places the connection type T and use the same pipe that you possess but completely continuous until the boost clock, therewith works perfectly I obtain sometimes up to 8.5 psi with the 2.6" pulley and the alky.

Well I think I figured out what was wrong with my gauge ..

Actually it's not the gauge at all ... apparently something IS wrong with my S/C

I was reading adn searchign so much this weekend my herad was spinning and I was about to give up when I read about the wastegate .. apparently mine was opening up after car would stat and staying open which is why my gauge was reading zero at WOT .. it actually not getting any boost ..

how do I know this ... I zip tied the wastegate closed and took it for a spin .. it works perfect .. reads boost at 5 psi and the car goes like a bat outta hell ..

so I am assuming something is wrong with the unit .. next step I need to contact someone to find out about sending it back to get checked out ..

I am having no good luck with this thing at all!!!!

Is the bypass valve working at all or was it not adjusted properly? Many disconnect or adjust the valve so it's open under boost until they have their computer flashed at the dealer.


12.770 @ 111.99 Intercooled Eaton M62

honestly, i zip tie all my fitting also, you cannot stress too many safe connections. I'd say it's the bypass valve which is that black plastic circle with a yellow label on it under the s/c. order up a new one from GM and replace it.

Airtonics wrote:Is the bypass valve working at all or was it not adjusted properly?

I really don't know if it's working or just not adjusted .. it seems to work for about 20 or 30 seconds when the car first starts up after the engine was off for a couple of minutes then it seems to stay open and the car sees no boost at all untill I turn it off .. let it sit then start it again ..

BOOSTED (the sticker guy!) wrote:honestly, i zip tie all my fitting also, you cannot stress too many safe connections. I'd say it's the bypass valve which is that black plastic circle with a yellow label on it under the s/c. order up a new one from GM and replace it.

I have a pretty good feeling it's the bypass valve that is not working

I really don't know much about this but I am learning

I am gonna try to get a new valve instead of taking the unit out and shipping it off