engine problem

[Castig3]

installed a mbc today and went out to test it first and it hesitated first at boost. My mechanic turned the mbc up, two shifts later, the car is giving off a loud rattling noise inside the block. The weird thing though is that the boost guage read 10psi when the mbc was installed and not turned on. Now it reads 6.5 psi still rattling sound with lots of lag, but still idle's well.

Narrowed the possiblities to:
wastegate
vacuum lines(vacuum was running at 10, shouldn't it be more?)
camshafts
valve train
rods

any help at all is much appreciated
i did look up similar problems in terms of boost problems but they aren't the same since the car still runs and theres no fuel cut

[Metallic36]

Did your mechanic by chance make you get a spun bearing by upping the boost? Are you forged? What exactly does it sound like? I'd tell the mechanic he had better come up with a solution since it was his idea to up the boost.. my car still drove after I killed my engine.. just a thought.

[Castig3]

its not a spun bearing, the noise is from the valve train, a valve lash/derived ticking noise. Are they automatically adjusted and are the lifters hydryalically lifted, thanks for your in put btw metallic36, the exhaust still sounds great

[msp1986]

i just installed an MBC too. that hesitation is normal its because it now has to build vac pressure up to your setting before it will pull the wastegate open. this is a normal feeling for an installed mbc it hesitates then hits all at once instead of slowly building. as for why its running 10 when its not set up im not sure other than the stock spring load on the mbc was 10 and when you turned it up it went way way high (10 is about as high as i would ever go even with all the right mods if your not forged or you will have a boat anchor) if your vac is siting at 10 and wasnt before you might have blown off a vac line... it is leaking somewhere my guess would be from the mbc itself if you dint find a blown off or cracked line

[Castig3]

i wish i would of know that before hand.....live and learn i guess, just gives me an excuse to keep modifying :)......even though i'll be car less for awhile

[msp1986]

ya boost controllers and our cars equal a very dangerous and risky operation its best to just get the atp wastegate which runs a little over stock safely without modify or tricking the car... without forged internals your really asking for problems over 10 or if you wanted to get particular anywhere over stock its just not built for it

[Castig3]

yeah thats on my list to order along with new vacuum lines, still trying to figure out what the ticking sound is