10psi or so problem

[AL92]

I have 91 fwd that am playing with till finish up my 97.
Its 14 b stock with no cat ,turbosmart mbc,boost guage,stock fuel.
I was trying to get it to 15psi. I can't seem to get past 10psi.I opened the boost control all the way but never did try unplugging the wastegate yet.
Car is running ok,bad idle surge though and vacuum is only 12 or so in hg.
I think its holding the 10psi or so but why won't it let me get past it.The boost controller is not in backwards.
I can't find any vacuum leaks in hoses.I have not boost leak tested the car.The low vacuum makes me think something is leaking..tb seals,intake gastet,injector seals.

 

[BaddAssGst]

I have 91 fwd that am playing with till finish up my 97.
Its 14 b stock with no cat ,turbosmart mbc,boost guage,stock fuel.
I was trying to get it to 15psi. I can't seem to get past 10psi.I opened the boost control all the way but never did try unplugging the wastegate yet.
Car is running ok,bad idle surge though and vacuum is only 12 or so in hg.
I think its holding the 10psi or so but why won't it let me get past it.The boost controller is not in backwards.
I can't find any vacuum leaks in hoses.I have not boost leak tested the car.The low vacuum makes me think something is leaking..tb seals,intake gastet,injector seals.

Definitely sounds like a boost leak. Hook it up to the tester and listen for leaks. You likely have a few of them.

 

[DSM90AWD]

I can't seem to get past 10psi.I opened the boost control all the way but never did try unplugging the wastegate yet

On my MBC "loosening" the screw (e.g. counter-clockwise) reduces boost, "tightening" (e.g. clockwise) increases boost

 

[AL92]

Well had it all the way in and all the way out.no real difference.I have another mbc coming in mail and am going to try to unhooking the wastegate hose for a test. That should tell me if its the boost controller,or point me in another direction.

 

[DSM90AWD]

am going to try to unhooking the wastegate hose for a test. That should tell me if its the boost controller,or point me in another direction.

Be careful, without a boost source to the wastegate actuator, your boost will not be limited.

Have you checked the basics, like is the WG flapper fully closed at rest? If it's not, you may need to add pre-tension to the actuator arm

 

[foreverinvayne]

i dunno about anyone else but if i was only running 12 inches of vacuum i'd be scared to try and boost above that... if ## engine is in good runing order you have a major boost leak/vacuum leak. otherwise the 12 inches of hg is telling you something even worse. I got scared when i started seeing just 16" hg... but that's because of a decent sized vacuum/boost leak i found.

 

[napkinthief]

not trying to hijack but i have a related question:

if you hook up a boost leak tester will it find vacuum leaks aswell? I am seeing -16 vac at idle, -20 when i let off the throttle, and 0 full throttle until I boost this tuesday

 

[AL92]

Guys a bit of update.I changed out injector seals and was going to change out j pipe gasket,blow off gasket and tb shaft seals and gaskets and check intercooler for holes.
and boost leak it after that if still had leaks because after all the above likely only the intake manifold could be leaking.
I pulled off air cleaner and it was as I suspected super dirty. I then reached into turbo and its big time messed up. It hits the wall and grinds and dont wan't to spin good at all.Also lots of oil in intake tract.I think its still recent as have run catch can for awhile. I also seem to have crank case pressurizing problems and not sure why. I ran straight thru pcv to catch can and then back to intake.
Yet my dipstick and think new oil cap are leaking and possibly my brand new valve cover gaskets as well.
Anyway I ordered another 14b so see how that works out. Sure will get past 10psi with that one but not sure why have the low vacuum .That is good question is a boost leak also going to cause low vacuum.

 

[AL92]

Thought would post a follow up. I switched the 14b for another one and get my 15 plus psi now. I will retest for boost leaks and know I have a leak at tb elbow.found out with a smoke machine tester at local shop. That seemed to be only leak on smoke machine.

I still have vacuum and rough idle problem. I have 14 in hg .I have tried to get rid of idle roughness with new isc,blocking fiav with tig welding,etc. But so far no luck.

 

[My96AWD]

I ran straight thru pcv to catch can and then back to intake.

If I read that right you have a hollow pcv valve hooked to a catch can then to the intake. If so then unplug it from the intake and cap the intake side. The pcv valve is a 1 way valve that lets pressure out but not in, if you hollowed it out then you are boosting your crankcase aswell.