i went from a stage 2 GM pulley and #42's, boost level of 15psi, and on days where it was 65 and below it would hit 17psi, now with my 2.8 zzp pulley, 3' ZZP catted DP, 60#'s, which i installed all at the same time, and for a little while it boosted 18-19psi, but now its 15 psi most of the time and sometimes it hits ~16.5psi and a loss of power like it probly slower then a stage 2 cobalt, any ideas? I installed a new block to intercooler gasket, intercooler to supercharger gasket, new by-pass, new boost line, idk what the hell it could be....like could it be the tune, or did i not tighten the intake down in the right pattern, which i could never find the right "pattern", could it be that i need to rebuild my supercharger, anything?

 

cause its 150 degrees outside

 

ya its a ra-tarded outside but no, i tested it out when it was 70 outside and same results....

 

I'm on a 2.8 pushing about 17 lbs.. It's about 90 degrees here.

 

could it be because the exhaust flows better therefore creating less boost that could be a factor can it no?

 

ya but i haven't touched my exhaust since i put it on and when i first installed that pulley it hit 17-19 and now it only hits 15....

 

Belt slipping?
Put the old pulley back on and see if it goes back to where it used to be.

 

i have a stage 2 belt, stock tensioner pulley.

 

that and if it was slipping it would or should jump to 17 once and a while, but maybe i should plug that one boost line and see if the relay or w/e is bad...

 

any idea's?

 

Turns out it was a bad intake gasket.

 

Boost controller limiting your max boost by opening the bypass valve. Try that boost mod thats somewhere in these forums, and see if that helps.

 

Read the post above your's...

 

How much did that end up running ya for parts and labor or did you do it yourself?

 

Depending on which Intake Gasket he needed... $15 or $31. More than likely the $31 one.

Cobalt SC Gasket 12584342 - Crate Engine Depot

Ecotec Intake Gasket 12597855 - Crate Engine Depot

 

i did it myself, still not the problem.

 

I built a boost leak tester, and when I hook it up it holds pressure till about 2.5psi, anything above it leaks out back down to 2.5, when i put 20psi in it makes a humming sound then Round 15psi the humming goes away and then its a hissing sound till 2.5 Psi, any ideas????

 

Still is only boosting 15-16 psi when it used to boost 17-18 solid!! and a loss of power.

 

first off u werent making that boost on the gm pulley im making 17.5 to 18 on 50* days on a 2.6

 

Hell I'm solid 15 on a 2.9 with a bad mab and 2.5 catted dp

 

i have the 2.8" pulley and im only boosting around 15 psi. i would say your doing fine. i don't think your tune is right for that pulley. thats why your loosing the power. you put that smaller pulley on and the car isnt reading that. get a tune see if that helps. and i would also go with a larger injector. i know just for safety i would go with the 60# injectors. i know the 45# start to max out around then on the 2.8" pulley. and also i see you have some exhaust work and intake work done to your car. boost is a number that shows restriction, so just because it is lower doesn't mean that is a bad thing. it just means with your exhaust and intake that your car is flowing better. other than that i think you ok. i am boosting the same numbers.

oh shoot i didn't see you had 60# injectors. my bad. ignore my comment about the injector size. good luck man!!

 

check for vaccuum leaks... could be anywhere.
if your exhaust was clogged up a little and it unclogged from you getting on it he boost could go down. also the boost gauges suck in these cars never really accurate... could be that as well.

and im running <20psi on a 2.8 tvs so its not always the pulley

 

Ok I ordered a zzp stage 3 kit, with a 2.8 pulley and pcm, at the same time I got a 3in zzp catted down pipe, I put them on all at the same time, for about a week it read 18psi, and pulled hard, then all of a sudden it pulled about as much as my GM stage 2 did, and read 15psi same as my GM stage 2. there is a small hissing noise under small amounts of throttle while moving, and when pressure tested hissing sound again and then a Humming sound and pressure leaks out till 2.5 psi then holds steady. ideas? And vacuum leak from where u think?

 

where do you here the hiss from? try to get someone to rev a little bit while you listen to the engine and try to find it. let me know if that works and where you found the hiss.

 

What is your boost when driving around town? Say you're at 2500rpm and you lug the motor. What boost levels do you see then?