10-11psi, Then After Driving A While 15psi? Wtf?

[turbotsi92]

I have been running my rebuilt engine at 10-11lbs of boost until I get enough miles on it to put synthetic oil in it, but I have my mbc turned almost all the way down. I drive my car hard and it runs 10-11psi until I have ran it for about 15-20 minutes. After that I get on it hard in 3rd or 4th, and it will be at 10-11psi until i hit about 4500rpms, then it starts climing to 15-17lbs of boost. I don't understand it. I can't turn down the boost anymore, or my mbc will be closed. I am just at a loss right now. Check the profile for mods.

 

[ddavisaf]

Here is what you should do. Wait until your car is nice and cool and run a boost leak test.
Then depending upon the results of the test (20 psi for 30 seconds at least), run your car until you start creeping to 15-17 psi. Then park it and run another boost leak test and see if you're leaking from anywhere else. Also look for an exhaust leak before the turbo that may be small enough to cause problems when cold, but when warm seals up and allows you to creep.

 

[Spoolin4Ever]

MBC hooked up incorrectly: reverse the 2 hoses that go to it, you have them backwards.

Unplug the 2 hoses, and plug them into the opposite sides they are currently plugged into.

Enjoy.

 

[eclipsegsx1736]

\ I can't turn down the boost anymore, or my mbc will be closed.

Not sure if you typed that correctly, but if you did, closing a MBC turns UP the boost. If you turn your boost down far enough on an MBC, you unscrew the knob, and eventually the knob will screw completely out of the hole. So if youre closing the MBC, youre running as much boost as the turbo can put out before it blows.

 

[dsmsucks]

MBC can be trashed?!?! What kind of mbc do you have?

 

[oldman]

I suspect the mbc is hooked up correctly and is functioning properly or else you should be getting all out boost like 20+ psi. I believe you have boost creep issue but covered up when car is cold due to boost leaks. When temperature rises, some of the leaks probably sealed themselves revealing the boost creep. First thing should be eliminating boost leaks in order to confirm boost creep so you can take proper measures against boost creep.

BTW Don't push the car until it's fully warmed up.

 

[turbotsi92]

I suspect the mbc is hooked up correctly and is functioning properly or else you should be getting all out boost like 20+ psi. I believe you have boost creep issue but covered up when car is cold due to boost leaks. When temperature rises, some of the leaks probably sealed themselves revealing the boost creep. First thing should be eliminating boost leaks in order to confirm boost creep so you can take proper measures against boost creep.

BTW Don't push the car until it's fully warmed up.

Thank you. I know my boost controller is hooked up properly, it is a turbo XS. This makes perfect sense.

 

[Flewbyu2easy]

Thank you. I know my boost controller is hooked up properly, it is a turbo XS. This makes perfect sense.

I had a turbo XS MBC and I was experiencing ridicules boost spike... I read a few reviews on the turbo XS MBC and everyone had the same problems... I bought a turbosmart MBC from a friend of mine... Problem sovled

Good luck

- Steve

 

[turbotsi92]

I had a turbo XS MBC and I was experiencing ridicules boost spike... I read a few reviews on the turbo XS MBC and everyone had the same problems... I bought a turbosmart MBC from a friend of mine... Problem sovled

Good luck

- Steve

Thanks man, I have to build a boost leak detector, and if I don't have any boost leaks I will try a new mbc.