Evo 16g not hitting full boost. Help!

[papasapusc]

Over the weekend I got a new E316g and put it on my car along with an atmospheric o2 housing. When I took it out for a test drive, it was not hitting full boost. My boost gauge read about 5-6psi, but it felt like I was pushing about 2 psi. It wasn't sputtering or anything, but when it would boost, it had no pull to it. This was on Monday, on Tuesday night, I was driving and it started to sputter a little when I was in low RPMs, up until about 2250-2500. It wouldn't do it all the time, but it is starting to do it a little more, mostly on hills. Also, since it started sputtering, it will cough out a little bluish smoke after I shift, but not a lot, and only when it sputters. I found a little crack on the top of the exhaust manifold and there was a little one on the inside of the collector, but it didn't look like it went all the way through. Could this be the reason that it is not boosting fully? And does anyone have an idea of what the sputtering could be, it feels a little like my plugs or wires are bad, but I just put the plugs in 6k miles ago, and I don't know how old the wires are, but they feel like they are on there pretty snug. Any opinions or advice would be greatly appreciated.

-Mike N.-
'91 GSX

 

[TSG59_Steve]

Boost leak test for one (Check the j-pipe), if you're not getting enough air then you will definitely sputter/die. Usually you can hear the exhaust leaking though.

 

[papasapusc]

Also, yesterday while I was driving, my hose fell off of the factory boost controller, so I was not hooked up the the wastegate, and it got up to about 17 psi, but still was not boosting, it had the same amount of pull as it did when it was reading 5 psi. Hopefully this will help with the finding of my problem.

-Mike N.-
'91 GSX

 

[JayRolla]

Major boost leak or exhaust leak. Sounds more like a leak between the mani and the turbo. My brother had this problem for a long time and come to find out the evo16g housing was warped from mitsu.

 

[viprez586]

There are numerous spots to look for. Check all your vac. hoses, Compressor Elbow Gasket, Compressor O-ring (both good places to RTV it), BOV flange, check all connections on your IC piping, check your TB gasket, Hopefully you dont have to replace your IM gasket, And lastly your injector seals are very common fail point. As for the cracks in the exhaust manifold, if you never took apart your exhaust manifold/ turbo depending on the mileage and /or abuse there could be major cracks. Any pre-turbo leak will severly affect spool time and how much PSI the turbo can hold.
Consider a 2g manifold as they outflow 1gs- Personally i run the SBR cast and love it-spool time is like whip-lash