So I am driving down the thruway, I put my foot to the floor, and the car only hits about 12 psi(should be about 19-21). so I let off the gas and about a minute later I try again from the same speed, and wham! slammed into the seat at about 20 PSI...this happens randomly while cruising where the PSI just isn't as strong as it should be under WOT.

So today I took off my front bumper(PITA) and proceeded to check all of the connections/clamps/hoses, everything was very tight. so after some reading I decide to check the BPV spring. I remove the plastic cap with the spring and rubber boot all attached...should the spring have a little more "bounce" to it? I mean I figured the spring should be strong enough to force the rubber boot out, right?

anyhow, I ordered a new bypass valve spring from dejon....for $13 including shipping, I figure if it doesn't fix it, I'm not out a fortune...

Also I understand the boost will be lower in colder temperatures. but the car is practically falling on its face when at WOT sometimes.

One other note....the opening of the turbo(when i removed the intake pipe to access the BPV easier) had some oil on it, along with some oil in the bottom of the tube....not sure if this is normal...

Thanks for any input and sorry to start another "boost issue" thread

 

Hey badassbowtie. I think I responded to another thread with the same problem. this boost problem happens to me to but I get about 15psi then when I let go then slam it again I get 23psi. I have the GMTU. As for the bypass valve I'm not sure because I have the forge Motorsport valve and still get this boost problem.

I've been wanting to swap out the spring for the stiffer one the valve comes with but I'm worried its gonna mess up my turbo.

Also for the oil inside the pipes I saw that too when I swapped out the valve. Now sure if its a problem but I know other people have seen the same thing.

 

My 2010 SS is at rockenbach Chevy now for the same issue with the GMTU .
The experts at Crate engine depot and the tech that will be working on it in the AM told me that if there is a fraction of a crack somewhere it is hard to find. System will hold boost to certain point , Then the presure opens the micro leak , Then boost drop.
I hope the certified bumper to bumper warranty , Or allstate will cover it.
SS was bought certifed used bumper to bumper for 48,000 miles or 4 years, With the GMTU installed .

Think i'll be ok ? .

 

so maybe upgraded I/C piping will fix this? I may be able to have it made out of mandrel bent aluminum with some connections through my brother...just got to draw it up for him...

 

when the boost fails to come in as expected..is the tranny downshifting?(auto).. or did you downshift? It may have been bogged down by gearing and not allowing it to boost....I noticed this also, but its holding the current gear so it stalls out until it shifts down....

 

it downshifts nicely either way...just sometimes you can feel your internal organs move(21psi).....other times, not so much(12psi)

 

Here is the link where we where discussing this before.
I wish there was a fix to this




https://www.chevyhhr.net/forums/show...=19891&page=29

 

update- New dejon bypass valve spring came today...after about 15 minutes of driving, my problem may be solved...I'm gonna give it a few days before I confirm it. the valve seemed release boost more often, and hold boost better unlike before, holding 17-19 psi at WOT. the new spring seems way stiffer than the old one...

 

I'm not really a fan of the dejon spring. It caused excessive flutter in certain conditions on my SS. Just watch out for flutter or BPV codes. If none, then ur good.