Well im the proud new owner of a 2006 evo IX. The previous owner did some work to it, it looks like an apexi cat back exhaust but i havent had it up on a lift to see if its a turbo back. he also installed some sort of cone filter air intake and a MBC. There is an autometer gauge installed and when i hit peak boost it tends to stay around 16 or 17 psi. I have to do a boost leak test on the car still to rule out a leak. I also plan on possibly taking the MBC off and just leaving that stock for now. I was looking at how it was hooked up and im pretty confused as to how everything goes back together without the controller. The guy completely bypassed the factory boost controller but he didnt cap off the inlet like it says to in most instructions. Does anyone have a diagram of all the vac line hookups? Also any other suggestions about the boost problem? i know most people will just say its a vac leak, and i hope its as easy as that, but would other types of problems can i be looking at? The car drives great and pulls real hard. I pretty much got the car because its a nice fast car thats reliable so im looking at keeping it as stock as possible for at least a little while, no matter how hard that may be. Thanks for all your help.

 

It´s pretty easy to do a boost leak test. I think that you´ll find step by step instructions on how to piece together the tester which you can source the bits for at Home Depot.

Also, you need to make sure that the MBC is properly hooked up: the bottom port on your MBC, which is the port directly opposite from the knob, should be routed to your boost reference source, which can either be the nipple on the compressor housing discharge tube, or alternately, a "T" fitting taken off of the hose that connects the intake manifold to the Diverter valve. The other, or side port on the MBC should be routed to the nipple on the WGA.

It´s probably best to start from scratch and replace whatever hoses the previous owner has installed, with brand new 4mm vacuum hose, secured with nylon zipties. This way you´ll make sure tha there are no vacuum leaks in the hoses and also verify that he didn´t leave the factory restrictor pills in the hoses.

If you just wanna get rid of the MBC and go back to the factory setup reincorporating the factory boost control solenoid, and the restrictor pills in the hoses, then the easiest thing to do is go to the dealership and for about $17 they´ll sell you a complete preassembled vacuum/boost hose assembly with the pills already properly located and including factory hose clamps.

What do you mean that he may have left the intake uncapped? Do you mean the nipple on the convoluted rubber intake hose, or the ports on the BCS?

 

Thanks for your help.
I plan on doing the boost leak test asap, im at school now and will be home weds to do it. I may keep the MBC in there for now if i can get everything up and running correctly and if i cant i might revert everything back to stock to see if it solves the problem and take it from there.

As for the intake uncapped what i ment was he cut the vac hoses that lead to the BCS and left the ones attached to the BCS unit itself open and vented to the atmosphere. Would cause any engine problems down the line? im going to cap it as soon as possible but i just didnt know if that would effect the computer readings since the BCS is always at atmospheric pressure and never under vacuum. Thanks again

 

Also what is the stock evo 9 boost level supposed to be in psi?

 

have you tried to adjust the boost u never said whether u did or not?

here is a thread with some different diagrams for hook ups
https://www.evolutionm.net/forums/sh...roller+install

 

Yes i have tried. When i first got the car i turned it down a bunch because didnt know the exact pressure it was running. I have been turning it up in small incriments but it has went from about 12psi to now about 17psi but i dont what to take a to a point where a turn it up too much at one time so i have been careful. Also if the MBC was set at the lowest setting shouldnt it be at stock boost? Thanks for the diagrams as well

 

no if it is turned all the way to the lowest setting, depending on different springs, it may not go any lower than 11 or say watever that boost controller will allow. stock setting is around 22-23, so just turn it up a little more. it sounds like it is working just fine

 

Ok ill have to play around with it a little more. Its such a new car i dont really want to do anything to ruin it yet. Ive had another turbo car and it was supposed to be running 9psi and the wastegate vac line was hooked up wrong so it wasnt opening and then damn thing boosted to about 16psi and lifted the head. Thats why im so hesitant on upping the boost so fast. Thanks for your help though