I just changed my bypass valve but I'm still boosting at 3psi. Anyone know any other factors to the low boost problem.

I have had this problem going on for a while now. I got my alternator changed at the dealer, had issues with battery light so in the process they swapped the ecu module... I figured i lost my tune and was boosting low because of that. Couple months later got the money for a new tune, changed the bypass valve and still boosting at 3 psi

Any ideas?

 

Maybe a stupid response but have you checked all of the vaccum lines?

 

oh yeah i did that... all are where they are supposed to be.

 

I don't know what to tell you... Maybe take it back to the dealer and tell them they effed up something since they were the last to touch it?

 

Do a boost leak test at your throttle body. Make sure the system is holding pressure. You could have a leaking injector seal or leaking gasket somewhere.

 

Yeah I would take it back to the dealer but it was like august when they fixed it, I figured they wouldn't even know what i'm talkin about or something or say it's too late. I honestly thought it was the tune at the time.

I will try a boost leak check.. Do i just get someone to rev up a bit while i listen for some air and stuff?

 

No you make a boost leak tester and a 2.75" coupler and hook it to your throttle body. Then you pressurize the system with an air compressor and spray soapy water any where air can leak. Then listen for leaks and watch for bubbles. I found I had a leaking injector seal by doing this. It's more of a turbo car thing to find leaks in the intercooler piping but it works for your intake manifold and such too.

http://www.youtube.com/watch?v=u3Kqh52PC6Q

Here's a video to make one. You don't need the gauge on it mine doesn't have it. All you need is the tire valve stem. Really easy to make and only about $10. All you do is get that pvc piece drill a hole and put a standard tire valve in there easy as that. I bought a 2.75-2.5 coupler for the cobalt since the throttle body is 2.75" and the pvc piece was 2.5''.

 

I would listen to him, he knows more about this than I do

 

lol ok good info! I will have to find some time to do this. School is cramming me with a lot of work so might have to wait a few more weeks to do this.

 

disconect the vaccum line coming from the intake and plug that will bypass the boost bypass solenoid then see what it does when you drive and have you tried swapping out the boost guage to see if it is bad

 

I have not tried swapping boost gauges.. i guess i could try that with my friend who has SS/SC also. And i will try bypassing the solenoid as soon as i find something to plug it with lol.

 

Does it feel slower then it should be? And did you get it tuned?

 

You can just screw a screw or bolt in the end of the vacuum hose to plug it.

 

Oh ok. ha


Yes, it feels slower from when i used to boost around 16ish psi. And i got it retuned by vince.

 

A dyno tune? Cause they would tell u if u were boosting that low, and have a good idea why. And did u try playing the line to the by-pass? To rule out your tune as an issue.

 

Nah i used the ez flash program to put the tune on my car and vince emailed me the tune. I will mess with that line as soon as i get the chance...