Which guage is it? I've heard a few people having issues with some of the Autometer guages, the Cobalt series in particular.

 

with that much vacuum, you have a gauge problem. joe from the other board had the same issue. that's 6.0ss. as for the power, it's hard to judge what you have. what are your maf readings?

 

1. did you seal off the fitting on the side of the throttle body, or is the hose still hooked to the valve cover and throttle body.
if it is still hooked up your are pumping boost in to the motor, seal this off at the throttle body.
2. I don't think your pipe is clogged or you would not idol due to the lack of air.
let alone run down the road and test it out.

3. remove the bypass valve, with the motor running rev it up a few times, as the rpm's build boost pressure should blow out of this hole very strong. hook the bypass valve back up to the pressure side, leave the return side unhooked and pointed towards you, rev the motor and build pressure if the valve is bad you will feel a burst of pressure from the hole letting you know it is bad., mine gave way at 5 psi.

you say you need to glue your fittings, with a spray bottle filled with soap and water hose the fittings and rev the motor, if it bubbles your losing boost, if it does not the fittings are fine.

as far as the cam being the issue we need to see the specs from the cam card to see how much overlap you have to see if your really bleeding off through the cylinders from open valves.

 

I have Autometer guages they are the phantom ones
I sealed off the fitting on the side of the throttle body and ran the hose from the valve cover over to the air filter tube.

my cam specs are
220/226 556/570 114+4

i would post pics but i can't get them to work then you guys could see everything i have done

 

Justin,
You must have a loose connection on the intercooler piping. Those gauges that I sent you were working when they were pulled out of the truck and you know that I wrapped them very carefully so I don't think they were damaged in shipment. I once blew a pipe loose at the intercooler and had the same issue. Just looking at it the connection looked fine but under boost you could feel the air blowing by. Like others have suggested you need to check everything several times over. I know it all worked when it was taken apart. I am sorry you are having difficulties but the ATI works and it works well. Keep and it and I am sure you will be satisfied with it.

Tim

PS. I sole my C3 today and will have the 05 Sierra Denali tomorrow!

 

You're not going to get any boost by just reving the engine in park...it need to be under a load in drive...like I said you need to verify the boost guage is working correctly...you should be able to disconnect the output hose at the SC and rev the engine in park....done outside at the TB and you should get a very large gush of air when reved.

Ken

 

So when your truck is turned off does your gauge read 0? It sounds like your gauge is not working right. I have a whipplechargered 5.7 and it only has 12-13 pounds of vac. I have a 558/558 221/221dur cam in mine and didn't loose any boost from this cam. You could check your gauge by not hooking up your supercharger (The belt) but running the rest of the ***. and reading your vac off the gauge. If you have high vac at wot your gauge is wrong. Hope this helps.

lator

Yellow

 

when the truck is turned off it goes to 30 vac

 

i called ati today and they said that i could have a loss of about 6psi of boost with my cam and headers.

 

I hate to hear that. I guess its time for a smaller pulley.

lator

Yellow