I drove my car roughly 45 mins last night to my girlfriends and everything was working fine. Came out this morning, drove it till it was warmed up and then walked on to it pulling on to the highway. WOT and I was only pushing 3psi.. Normally I'm running 12psi. I'm on GM Stg 2, vibrant header/catless dp, corsa 2.5" catback, Cxracing h/e, step one colder plugs, 2.85" pulley and an Injen cai.

Any ideas? Bypass valve? Maf?(I through a code a few days ago, just thought it picked up some moisture) It doesn't show any signs that the belt is slipping.

 

seems like your car is in limp mode, also with stage 2, you should be pushing 15-17psi, stock cobalts run 12 psi

 

Isn't it supposed to show up on your DIC if it's in limp mode? And I'm not throwing any codes.

 

stage 2 runs about 15 psi with no bolt ons. 12 psi is fine for stage 2 and those mods. check for boost leaks

 

Where would I look for boost leaks on an SC? Gaskets between the SC, IM and head?

 

all the above plus the actuator or whatever its called on the blower. Check the lines from the actuator all the way to the valve.

 

boost bypass selonoid is bad i bet you a dollar

 

lol if you have stage 2 and your only getting 12 psi then your car is fuuucked, cobalt ss/sc runs 12 psi stock, and if he has all those mods in his sig, then he should be hitting 17 psi at the end of 2nd and 3rd gear and should be getting there pretty quickly

 

boost is only a measure of restriction, i had about 14psi and a 2.8 pulley with a bigger header, 3 " catless dp and a gmpp exhaust, he has a high flow exhaust, and depending on the altitude, temp, and a bunch of other factors, his numbers might be correct...

 

boost measures pressure, and if your only getting 14psi then you also have something wrong, he might be at higher alt. but it shouldnt effect by 3-5psi of boost

 

its actually been seen before that stock lsj engines have ran from 8-12 psi on stock pullies, and 12-16 on gm stage 2 tunes, there's been threads and threads about it lol, im not here to argue just sharing my own experience

 

i understand, but for the most part there are things to do to make sure you get as much boost outa your mods as you can

 

gm stg2 runs 15lbs altitude will show less but not 12lbs less

 

Boost measures atmospheres or pressure beyond 14.7psi. Having the "most boost outa your mods" is to much of a blanket statement. Every single car that is combustion based benefits from a simple concept, more fuel and more oxygen equals more energy.

If you had a m62 car with stock pulley and you run 12lbs of boost then port your intake manifold allowing a greater volume of air thus reducing the amount of pressure contained under a certain CFM you would in effect have the same power available with less manifold pressure. If you then pullied down or increased the CFM of the supercharger you would see the same boost number on your guage but be flowing much more air and with a adequet fuel supply, map and timing table create much more power.

 

x2.... try doing the bypass mod and see if anything changes

 

More boost doesnt mean more power lol. Supporting mods like exhaust mani, dp, catback won't add boost to your car. They help your system flow better so if anything decreasing boost levels and creating a more efficient system.

 

Yeah man, something is up. When I had the car I was pushing between 17-18psi and the car worked good. The belt may be slipping, or the bypass valve could be ******* up. The gaskets should be fine unless you have had it apart and re used the gasket. Pat has that smoke machine now so take it to him. If you have a leak, that dye will show it.

 

It hasn't pushed 17-18psi since I bought it. It's been between 12-14psi.

 

bypass valve p0300 or p0033 bypass/wastegate position sensor. I posted this same prob one week ago. no one willing to help me then. how you determine which it is, find ur bypass valve, remove the bottom vac line on the bypass valve and plug the line with like a screw or sumtn for your tryn to determine wether its the valve or sensor. take it down the road and it should boost up for you. if it dont chances are its the valve. My car boosted and it was my sensor that was bad not the valve. you may have no cel but it prob is stored in the comp still. limp mode gets thrown around on her just as much as the bs flag, not enuf hands on from enuf people on here to state what to do in my eys but best of luck op. Mrbelv knows alot bot car pm him or someone legit for youll get taken in all kinds of directions for diff probs and waste time and money.

 

there is an oring inside that goes bad

 

He's running a 2.85" nates pulley as well....

 

Exactly what I was going to suggest. Had a friend that had this same issue and we replaced his solenoid and it solved the problem.

 

pst, with a blower the guy making the least boost with the same size pulley is making more power.

 

yup..

 

So I pulled the line of the valve that goes from the sc to the valve and plugged it and it still isn't building boost.. Any other ideas?