Not building boost

[1eightySX]

I wish I had more to contribute to this forum but it would seem the only time I write is when I have a problem. Which brings me to my next point, I have a 91 180sx (redtop Sr). I have been having a problem that it is not going past 4000 rpm as well it stops builing boost at about 1.8 hkpa. Allow me to explain my situation, last night I was dry fitting my pipping for a front mount intercooler. In doing so I disconnect the pipe running from the throttle and of course re-connected it. Today I was driving and my car would not boost past the 4.5 hkpa, this seemed strange as it usally boosts at 5.3 hkpa. So while trying to diagnose the problem i was playing with the boost controller but much to my dismay it would not go over 4.5 hkpa. When i stopped the car I re adjusted the pipe runing from the throttle and tightened down so more. For the next two minutes my car ran perfect but seeing as how I had been playing with the boost contoller it was boosting higher than usual. I heard a pop while driving and then my car it began to lag. I heard the pop at 6.2 hkpa but i don't know where it came from. Now I know it is not safe to boost over 7 psi in a stock sr20det but I have upgraded my fuel pump, but with all that being said, did I somehow blow my turbo? Would a turbo still build a little boost if blown or is this a whole differnt problem?

[DriftSwift]

Well it all depends on what part of the turbo blew. If it's seals then yes the turbocharger will make boost. OR if it blew blades, then no it will not boost. Check it for difference in sound. like an exhaust leak. There you can check if the housing are cracked. MOST of the time the cracks are small and will not be heard. But as for your boosting problem. Does it not make boost after 4.5HKPA or does it hold a certain amount of boost at 4.5? Does it drop off ? If you install an aftermarket i/c set-up you will lose boost. But since wastegates are set-up to regulate at +manifold pressure, then you will actually make more boost over stock i/c.

[nismo-joe]

have you checked for boost leaks? the pop you heard could ahve been blowing a coupler, and resulting in a small leak.

[1eightySX]

Ok, that does make sense it is holding boost. And I should mention that I put the decimal in the wrong place for hkpa they should all read as follows 0.53hkpa, 0.45 hkpa and 0.18 hkpa. To translate that into psi it would be 7.5 psi, 5psi and now 2psi. maybe my problem could have something to do with the fact that it is not accelerating past 4000rpm maybe I am paying too much attention to the boost gauge. Any further advice would be great anf thanks for the advice i will be checking that out.

[pab_drifter]

dont check if you have a boost leak!


find a boost leak that could be teh only resonable explination
tighten any clamps you see or no wer any clamps are
exspecially teh intercooler piping

[1eightySX]

you are exactly right, I found the problem. Somehow the piping popped off pre blow off valve. Thanks everyone for the help.....I am an idiot who loves to over re act when something goes wrong. If it wasn't for you guys I would be laying face down in a drain pool somewhere, not actually... but probably broke from paying people to fix my car. Thanks again.