300zx TT Boost loss question.

[dallen]

I have a 1991 zed TT have had it a little over three months now...
I have not ran a boost leak test on the car yet but have checked all clamps & have got new intercoolers installed..
but I am not SURE if it is leak or not...

The car runs like a dream for about 3-4 miles on a cold start & will push good boost until its warmed up.. then I suddenly loose 3ibs of boost..
My brother/Nissan tech tells me It is because I do not have the hard pipe kit for which creates the engine to heat up the tubes & expand resulting in me losing a little boost..

DOES ANYONE have an opinion on this or any other trouble shooting methods I might be able to do to fix and or find the problem...
im just not convinced its the rubber pipes expanding but it could be.. I was thinking maybe wastegate failure. plz help

[Ace2cool]

Not the pipes, unless you're running some crazy boost. There may be a cracked hose or vacuum line or anything really. If you're lucky, it may also cause a slight vacuum leak that can be detected with ether. There's a ton of possibilities, though, and the only real way to figure anything out is the boost leak test.

[DCaff300ZX]

I agree with Ace on the front side of this issue, hopefully that is the case. Check your idle air control valve and all of those larger hoses which also connect to the PCV's, and also check the nozzles coming out of the valve covers as they come loose and may also produce a vacuum/boost leak. BTW, a vacuum leak becomes a boost leak under boost so keep that in mind.

As for further advice if you find nothing wrong in those areas as I did not during my own issues, it was determined later by my Z mechanic that ALL of my various seals were leaking enough, along with some timing issues related to an improper tb install and further "mods", that combined would not produce boost past 1-2 psi which mimicked turbo failure and IACV issues which actually never was the case.

Hope this helps...