first off brought car from vermont (408ft) to Wyoming (7200ft) so iknow its probably altitude. i was boost 16-18psi of boost back home and come to wyoming and now only boosting 5psi normal and high 7psi. still havent fixed my cam chain tensioner problem nor valve stem seals. car wasnt driven 6 months thats why i didnt fix the problem. any thoughts would be really helpful. will be ordering the new cam chain tensioner soon. car is at 195k on the engine

 

You're in safety boost. Fix your known issues (as at least the CCT can influence this), and then reassess the problem.

 

I would bet you can a leaking vacuum line or a cracked boost line. I doubt the chain tensioner is related to your problem. Have u scanned it to see if there is a type 2 code that hasnt triggered your CEL yet?

 

i pulled 3 codes yesterday bank 2 O2 sensor, unaficient flow in cat, and a heater/tempature sensor. and i was boosting 18psi with the cam chain bad. i checked my vaccume lines and boost line and they arent cracked nor leaking. contacted GIAC today and they said altitude wouldnt cause a boost drop.

 

With the engine running you don't hear any hissing from anywhere around the manifold lines? Gently try seperating your suction pump to see it the plastic weld has seperated.. I may be a O2 sensor issue, just more rare.

 

I will try that today. I don't hear any hissing coming from/near my manifold or engine.

 

so last week while driving at 5psi of boost i hear a hissing noise comming from the passenger side of the engine bay. when i took off the n75 valve sensor i was only capable of 3psi of boost, then i pulled the top line like been told to try and still was only boosting 5psi. car does smoke on start up and down shifts.

 

where is the suction pump located?

 

It's basically a three way check valve but big (about two inches long and is all black) it will have three vacuum lines on it and sits right behind the back of the manifold I. Top near the bulkhead.. These also have an issues with one port plugin up.. I would recommend just replacing it because if you haven't gotten the updated version part this will eventually cause a hard brake pedal because it control boost and brake vacuum supply.. Critical piece to be made of plastic..